Dosing & Uses
Dosage Forms & Strengths
estradiol/norethindrone acetate
tablet
- 1mg/0.5mg
- 0.5mg//0.1mg
patch, extended release
- 0.05mg/0.25mg per 24 hr
- 0.05mg/0.14mg per 24 hr
Menopause & Vasomotor Symptoms
Oral tablets: 1 tablet PO qDay
Patch: Apply 1 patch to lower abdomen continuously, changed 2 times a week
Alternative patch regimen: 1 estradiol patch (0.05 mg/d) days 1-14, changed 2 times a week; then 1 patch on days 15-28, changed 2 times a week
Indications
- Activella, Lopreeza, Mimvey (1 mg/0.5 mg or 0.5 mg/0.1 mg): Treatment of moderate-to-severe vasomotor symptoms due to menopause in patients with an intact uterus, and for prevention of osteoporosis in postmenopausal women with an intact uterus
- Activella, Lopreeza. Mimvey (1 mg/0.5 mg): Treatment of moderate-to-severe symptoms of valvar/vaginal atrophy due to menopause
- CombiPatch: Treatment of moderate to severe vasomotor symptoms in menopause, vulvar/vaginal atrophy; treatment of hypoestrogenisms due to hypogonadism, castration, or primary ovarian failure
Not indicated
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
Contraindicated (1)
- ospemifene
ospemifene, estradiol. Either increases effects of the other by pharmacodynamic synergism. Contraindicated.
Serious - Use Alternative (47)
- abametapir
abametapir will increase the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.
abametapir will increase the level or effect of estradiol by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP1A2 substrates. If not feasible, avoid use of abametapir.
abametapir will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir. - acitretin
acitretin decreases effects of norethindrone acetate by unknown mechanism. Contraindicated. Contraceptive failure may result.
- anastrozole
estradiol decreases effects of anastrozole by pharmacodynamic antagonism. Contraindicated. Estrogen may diminish the pharmacologic action of anastrozole. Coadministration not recommended.
- antithrombin alfa
estradiol decreases effects of antithrombin alfa by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- antithrombin III
estradiol decreases effects of antithrombin III by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- apalutamide
apalutamide will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.
apalutamide will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed. - argatroban
estradiol decreases effects of argatroban by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- belzutifan
belzutifan will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of belzutifan with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective nonhormonal contraception. Based on animal studies, belzutifan can cause fetal harm.
- bemiparin
estradiol decreases effects of bemiparin by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- bivalirudin
estradiol decreases effects of bivalirudin by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- carbamazepine
carbamazepine will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
carbamazepine will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia). - cimetidine
cimetidine will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- enzalutamide
enzalutamide will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).
- clarithromycin
clarithromycin will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- dalteparin
estradiol decreases effects of dalteparin by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- enoxaparin
estradiol decreases effects of enoxaparin by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- enzalutamide
enzalutamide will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- erdafitinib
erdafitinib will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.
- erythromycin base
erythromycin base will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- erythromycin ethylsuccinate
erythromycin ethylsuccinate will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- erythromycin lactobionate
erythromycin lactobionate will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- erythromycin stearate
erythromycin stearate will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- fexinidazole
fexinidazole will increase the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.
fexinidazole will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates. - fondaparinux
estradiol decreases effects of fondaparinux by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- fosphenytoin
fosphenytoin will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).
- givosiran
givosiran will increase the level or effect of estradiol by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP1A2 substrates with givosiran. If unavoidable, decrease the CYP1A2 substrate dosage in accordance with approved product labeling.
- heparin
estradiol decreases effects of heparin by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- idelalisib
idelalisib will increase the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates
idelalisib will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates - ivosidenib
ivosidenib will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternate therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.
ivosidenib will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternative therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs. - lumacaftor/ivacaftor
lumacaftor/ivacaftor will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).
- nefazodone
nefazodone will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- mavacamten
mavacamten will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten may decrease systemic exposures of ethinyl estradiol and progestin, which may lead to contraceptive failure or an increase in breakthrough bleeding. Advise patients to use a contraceptive method that is not affected by CYP450 enzyme induction (eg, intrauterine system) or add nonhormonal contraception (eg, condoms) during coadministration and for 4 months after last mavacamten dose.
- mitotane
mitotane will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).
- pacritinib
estradiol will decrease the level or effect of pacritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- phenindione
estradiol decreases effects of phenindione by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- phenobarbital
phenobarbital will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).
- phenytoin
phenytoin will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).
- primidone
primidone will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).
- protamine
estradiol decreases effects of protamine by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.
- quinidine
quinidine will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.
- rifabutin
rifabutin will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
rifabutin will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia). - rifampin
rifampin will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
rifampin decreases levels of norethindrone acetate by increasing metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia). - St John's Wort
St John's Wort will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- rifapentine
rifapentine will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).
- topiramate
topiramate will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).
- tucatinib
tucatinib will increase the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.
tucatinib will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling. - voxelotor
voxelotor will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.
voxelotor will increase the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.
Monitor Closely (187)
- albiglutide
norethindrone acetate decreases effects of albiglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.
estradiol decreases effects of albiglutide by pharmacodynamic antagonism. Use Caution/Monitor. Estradiol may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients. - amikacin
amikacin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- atazanavir
atazanavir, norethindrone acetate. Either decreases effects of the other by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Use alternatives if available.
- amiodarone
amiodarone will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- amobarbital
amobarbital will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- amoxicillin
amoxicillin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- apalutamide
apalutamide will decrease the level or effect of estradiol by increasing elimination. Use Caution/Monitor. Apalutamide induces UGT and may decrease systemic exposure of drugs that are UGT substrates.
- aprepitant
aprepitant will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- armodafinil
armodafinil will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- artemether/lumefantrine
artemether/lumefantrine will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- atazanavir
atazanavir, estradiol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Atazanavir may increase or decrease levels of estradiol. Use alternatives if available.
- atorvastatin
atorvastatin will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- azithromycin
azithromycin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Modify Therapy/Monitor Closely.
- aztreonam
aztreonam will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- belzutifan
belzutifan will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If unable to avoid coadministration of belzutifan with sensitive CYP3A4 substrates, consider increasing the sensitive CYP3A4 substrate dose in accordance with its prescribing information.
- bosentan
bosentan will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- bosutinib
bosutinib increases levels of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- budesonide
budesonide will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- butabarbital
butabarbital will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- butalbital
butalbital will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- cannabidiol
cannabidiol, estradiol. affecting hepatic enzyme CYP1A2 metabolism. Modify Therapy/Monitor Closely. Owing to the potential for both CYP1A2 induction and inhibition with the coadministration of CYP1A2 substrates and cannabidiol, consider reducing dosage adjustment of CYP1A2 substrates as clinically appropriate.
- cefaclor
cefaclor will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- cefadroxil
cefadroxil will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- cefamandole
cefamandole will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- cefazolin
cefazolin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- cefepime
cefepime will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- cefixime
cefixime will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- cefpirome
cefpirome will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- cefprozil
cefprozil will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- ceftazidime
ceftazidime will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- ceftibuten
ceftibuten will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- cenobamate
cenobamate will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
cenobamate will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate. - cephalexin
cephalexin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- clobazam
clobazam will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Clobazam is a weak CYP3A4 inducer; effectiveness of hormonal contraceptives may be diminished when given concurrently with clobazam. Additional non-hormonal forms of contraception are recommended.
- chloramphenicol
chloramphenicol increases levels of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. May increase side effects.
- chlorhexidine oral
chlorhexidine oral will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- ciprofloxacin
ciprofloxacin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- clarithromycin
clarithromycin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Modify Therapy/Monitor Closely.
clarithromycin will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - clindamycin
clindamycin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- clotrimazole
clotrimazole will decrease the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- conivaptan
conivaptan will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- cortisone
cortisone will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- crofelemer
crofelemer increases levels of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.
- cyclosporine
cyclosporine will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
cyclosporine will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - dabrafenib
dabrafenib will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.
dabrafenib will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. - dapsone
dapsone will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- elagolix
elagolix decreases levels of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.
- darifenacin
darifenacin will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- darunavir
darunavir will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- dasatinib
dasatinib will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- deferasirox
deferasirox will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- demeclocycline
demeclocycline will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- dexamethasone
dexamethasone will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- DHEA, herbal
DHEA, herbal will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- diltiazem
diltiazem will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- doxycycline
doxycycline will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- dronedarone
dronedarone will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
dronedarone will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - efavirenz
efavirenz will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- elagolix
elagolix will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.
- eliglustat
eliglustat increases levels of estradiol by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the P-gp substrate and titrate to clinical effect.
- encorafenib
encorafenib, estradiol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.
- ertapenem
ertapenem will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- erythromycin base
erythromycin base will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Modify Therapy/Monitor Closely.
erythromycin base will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - erythromycin ethylsuccinate
erythromycin ethylsuccinate will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Modify Therapy/Monitor Closely.
erythromycin ethylsuccinate will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - erythromycin lactobionate
erythromycin lactobionate will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Modify Therapy/Monitor Closely.
erythromycin lactobionate will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - erythromycin stearate
erythromycin stearate will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Modify Therapy/Monitor Closely.
erythromycin stearate will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - eslicarbazepine acetate
eslicarbazepine acetate will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- etravirine
etravirine will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- exemestane
estradiol decreases effects of exemestane by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens or estrogen-containing products, including combined oral contraceptives, should not be given concomitantly with exemestane; these drugs could interfere with the pharmacologic action and efficacy of exemestane.
- exenatide injectable solution
norethindrone acetate, exenatide injectable solution. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide. .
estradiol, exenatide injectable solution. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide. . - exenatide injectable suspension
estradiol, exenatide injectable suspension. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide.
norethindrone acetate, exenatide injectable suspension. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide. - fedratinib
fedratinib will increase the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
fedratinib will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary. - felodipine
felodipine will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- iloperidone
iloperidone increases levels of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.
- fexinidazole
fexinidazole will increase the level or effect of estradiol by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
- fleroxacin
fleroxacin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- fluconazole
fluconazole will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- fludrocortisone
fludrocortisone will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- fosamprenavir
fosamprenavir will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- fosfomycin
fosfomycin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- fosphenytoin
fosphenytoin will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
fosphenytoin will decrease the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - fostamatinib
fostamatinib will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Concomitant use of fostamatinib may increase concentrations of P-gp substrates. Monitor for toxicities of the P-gp substrate drug that may require dosage reduction when given concurrently with fostamatinib.
- gemifloxacin
gemifloxacin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- gentamicin
gentamicin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- glecaprevir/pibrentasvir
glecaprevir/pibrentasvir will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- grapefruit
grapefruit will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- griseofulvin
griseofulvin will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- hemin
estradiol decreases effects of hemin by pharmacodynamic antagonism. Use Caution/Monitor. Drugs that increase delta-aminolevulinic acid synthetase may decrease hemin effect.
- hyaluronidase
estradiol decreases effects of hyaluronidase by Other (see comment). Use Caution/Monitor. Comment: Estrogens, when given in large systemic doses, may render tissues partially resistant to the action of hyaluronidase. Patients may require larger amounts of hyaluronidase for equivalent dispersing effect.
- hydrocortisone
hydrocortisone will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- iloperidone
iloperidone increases levels of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.
- indinavir
indinavir will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
indinavir will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - insulin degludec
estradiol decreases effects of insulin degludec by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens may impair glucose tolerance.
norethindrone acetate decreases effects of insulin degludec by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance. - insulin degludec/insulin aspart
norethindrone acetate decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.
estradiol decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens may impair glucose tolerance. - insulin inhaled
estradiol decreases effects of insulin inhaled by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens may impair glucose tolerance.
norethindrone acetate decreases effects of insulin inhaled by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance. - istradefylline
istradefylline will increase the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.
istradefylline will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates. - itraconazole
itraconazole will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
itraconazole will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - liraglutide
norethindrone acetate decreases effects of liraglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.
- ivacaftor
ivacaftor increases levels of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.
- ketoconazole
ketoconazole will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
ketoconazole will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - lamotrigine
estradiol decreases levels of lamotrigine by increasing hepatic clearance. Use Caution/Monitor.
- lapatinib
lapatinib will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
lapatinib will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - letermovir
letermovir increases levels of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- levofloxacin
levofloxacin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- levoketoconazole
levoketoconazole will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
levoketoconazole will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - linezolid
linezolid will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- liraglutide
estradiol decreases effects of liraglutide by pharmacodynamic antagonism. Use Caution/Monitor. Estradiol may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.
- lomitapide
lomitapide increases levels of estradiol by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Consider reducing dose when used concomitantly with lomitapide.
- lopinavir
lopinavir will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- loratadine
loratadine will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- lovastatin
lovastatin will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- lumefantrine
lumefantrine will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- maraviroc
norethindrone acetate increases levels of maraviroc by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.
- marijuana
marijuana will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- meropenem
meropenem will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- meropenem/vaborbactam
meropenem/vaborbactam will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- metformin
estradiol decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.
- methylprednisolone
methylprednisolone will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- metronidazole
metronidazole will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
metronidazole will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. - miconazole vaginal
miconazole vaginal will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- mifepristone
mifepristone will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
mifepristone decreases effects of norethindrone acetate by pharmacodynamic antagonism. Use Caution/Monitor. Backup contraceptive method recommended. - minocycline
minocycline will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- rucaparib
rucaparib will increase the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.
- mitotane
mitotane decreases levels of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.
- moxifloxacin
moxifloxacin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- nafcillin
nafcillin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
nafcillin will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. - nefazodone
nefazodone will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- nelfinavir
nelfinavir will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- neomycin PO
neomycin PO will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- nevirapine
nevirapine will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- nicardipine
nicardipine will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- nifedipine
nifedipine will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
nifedipine will decrease the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - nilotinib
nilotinib will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
nilotinib will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - nitrofurantoin
nitrofurantoin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- ofloxacin
ofloxacin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- oxcarbazepine
oxcarbazepine will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- oxytetracycline
oxytetracycline will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- paromomycin
paromomycin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- pentobarbital
pentobarbital will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- phenobarbital
phenobarbital will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
phenobarbital will decrease the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - phenytoin
phenytoin will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
phenytoin will decrease the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - pivmecillinam
pivmecillinam will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- ponatinib
ponatinib increases levels of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- posaconazole
posaconazole will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- prednisone
prednisone will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- primidone
primidone will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- quercetin
quercetin will decrease the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- quinupristin/dalfopristin
quinupristin/dalfopristin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
quinupristin/dalfopristin will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. - ranolazine
ranolazine will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- ribociclib
ribociclib will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- rifampin
rifampin will decrease the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- rifapentine
rifapentine will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- ritonavir
ritonavir will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
ritonavir will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - roxithromycin
roxithromycin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Modify Therapy/Monitor Closely.
- rufinamide
rufinamide decreases effects of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Rufinamide is a weak inducer of the CYP 3A4 enzyme and can decrease exposure of drugs that are substrates of CYP3A4. .
rufinamide will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. - secobarbital
secobarbital will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- siltuximab
siltuximab, norethindrone acetate. Other (see comment). Use Caution/Monitor. Comment: CYP450 activity in the liver is down regulated by infection and inflammation stimuli including cytokines (eg, IL-6); inhibition of IL-6 by siltuximab may restore CYP450 enzymatic activity; caution if coadministered with CYP substrates that have a narrow therapeutic index.
- simvastatin
simvastatin will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- sirolimus
sirolimus will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- somapacitan
estradiol decreases effects of somapacitan by Other (see comment). Modify Therapy/Monitor Closely. Comment: Oral estrogens may reduce the serum IGF-1 response to somapacitan. Patients may require higher somapacitan dosages. See drug monograph for starting dose recommendations.
- St John's Wort
St John's Wort will decrease the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- stiripentol
stiripentol, estradiol. affecting hepatic enzyme CYP1A2 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP1A2 inhibitor and inducer. Monitor CYP1A2 substrates coadministered with stiripentol for increased or decreased effects. CYP1A2 substrates may require dosage adjustment.
stiripentol, norethindrone acetate. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment. - streptomycin
streptomycin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- tazemetostat
tazemetostat will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- sulfadiazine
sulfadiazine will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- sulfamethoxazole
sulfamethoxazole will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- sulfisoxazole
sulfisoxazole will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- tacrolimus
tacrolimus will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- tazemetostat
tazemetostat will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- tecovirimat
tecovirimat will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.
tecovirimat will decrease the level or effect of norethindrone acetate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered. - teicoplanin
teicoplanin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- temocillin
temocillin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- teriflunomide
teriflunomide decreases levels of estradiol by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
- tetracycline
tetracycline will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- ticarcillin
ticarcillin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- tigecycline
tigecycline will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- tobramycin
tobramycin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- tolvaptan
tolvaptan will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- topiramate
topiramate will decrease the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- trazodone
trazodone will decrease the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- trimethoprim
trimethoprim will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- valproic acid
estradiol will decrease the level or effect of valproic acid by increasing elimination. Modify Therapy/Monitor Closely. May lead to increased seizure frequency
- vancomycin
vancomycin will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
- verapamil
verapamil will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
verapamil will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. - voriconazole
voriconazole will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- warfarin
estradiol increases effects of warfarin by unspecified interaction mechanism. Use Caution/Monitor.
- zafirlukast
zafirlukast will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
Minor (32)
- amitriptyline
estradiol, amitriptyline. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- amoxapine
estradiol, amoxapine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- androstenedione
androstenedione increases effects of estradiol by pharmacodynamic synergism. Minor/Significance Unknown.
- boron
boron increases levels of estradiol by altering metabolism. Minor/Significance Unknown.
- clomipramine
estradiol, clomipramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- cyanocobalamin
estradiol decreases levels of cyanocobalamin by altering metabolism. Minor/Significance Unknown.
- desipramine
estradiol, desipramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- dosulepin
estradiol, dosulepin. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- doxepin
estradiol, doxepin. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- folic acid
estradiol decreases levels of folic acid by altering metabolism. Minor/Significance Unknown.
- imipramine
estradiol, imipramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- isoniazid
isoniazid will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- L-methylfolate
estradiol decreases levels of L-methylfolate by altering metabolism. Minor/Significance Unknown.
- lofepramine
estradiol, lofepramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- magnesium chloride
estradiol decreases levels of magnesium chloride by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.
- magnesium citrate
estradiol decreases levels of magnesium citrate by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.
- magnesium hydroxide
estradiol decreases levels of magnesium hydroxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.
- magnesium oxide
estradiol decreases levels of magnesium oxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.
- magnesium sulfate
estradiol decreases levels of magnesium sulfate by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.
- maprotiline
estradiol, maprotiline. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- metyrapone
estradiol decreases effects of metyrapone by unspecified interaction mechanism. Minor/Significance Unknown.
- mycophenolate
mycophenolate decreases effects of estradiol by unknown mechanism. Minor/Significance Unknown. Clinical significance unclear.
- nortriptyline
estradiol, nortriptyline. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- phytoestrogens
phytoestrogens decreases effects of estradiol by pharmacodynamic antagonism. Minor/Significance Unknown.
- pleurisy root
pleurisy root decreases effects of estradiol by unspecified interaction mechanism. Minor/Significance Unknown. Theoretical interaction.
- protriptyline
estradiol, protriptyline. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- pyridoxine
estradiol decreases levels of pyridoxine by altering metabolism. Minor/Significance Unknown.
- pyridoxine (Antidote)
estradiol decreases levels of pyridoxine (Antidote) by altering metabolism. Minor/Significance Unknown.
- ropinirole
estradiol increases levels of ropinirole by unspecified interaction mechanism. Minor/Significance Unknown.
- rose hips
estradiol decreases levels of rose hips by increasing elimination. Minor/Significance Unknown.
- trazodone
estradiol, trazodone. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
- trimipramine
estradiol, trimipramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.
Adverse Effects
>10%
Amenorrhea
Breakthrough bleeding
Change in menstrual flow
Spotting
Edema
Anorexia
Weakness
Frequency Not Defined
Change in weight
Depression
Dizziness
Headache
Nervousness
Somnolence
Breast tenderness
Galactorrhea
Abdominal pain
Nausea/vomiting
Cholestatic jaundice
Deep vein thrombosis
Thrombophlebitis
Postmarketing reports
Endometrial hyperplasia
Endocervical polyp
Uterine leiomyomata
Fallopian tube cyst
Uterine spasms
Breast cancer
Hypertension
Varicose veins
Jaundice cholestatic
Cholelithiasis
Gall bladder disorder
Transaminases increased
Skin discoloration
Lability affected
Libido disorder
Migraine
Vertigo
Paresthesia
Angioedema
Hypersensitivity
Weight increased
Warnings
Black Box Warnings
Cardiovascular risks
- Estrogens with and without progestins should not be used to prevent cardiovascular disease
- Estrogens plus progestins: Women’s Health Initiative (WHI) Estrogen Plus Progestin substudy reported increased risks of myocardial infarction, stroke, invasive breast cancer, pulmonary emboli, and deep vein thrombosis (DVT) in postmenopausal women (aged 50-79 yr) during 5.6 yr of treatment with daily PO conjugated estrogens (CE 0.625 mg) combined with medroxyprogesterone acetate (MPA 2.5 mg) compared with placebo
- Estrogens alone: The estrogen alone substudy of the WHI Study reported increased risks of stroke and DVT in postmenopausal women (aged 50-79 yr) during 6.8 yr of treatment w/ oral conjugated estrogens (0.625 mg/day) alone compared with placebo
Dementia risks
- Estrogens with and without progestins should not be used to prevent dementia
- Women's Health Initiative Memory Study (WHIMS), a substudy of the WHI study, reported increased risk of developing probable dementia in postmenopausal women aged 65 yr or older during 4 yr of treatment with daily CE 0.625 mg combined with MPA 2.5 mg, compared with placebo
- Estrogens alone: A substudy of the WHIMS reported an increased risk of developing probable dementia in postmenopausal women aged 65 yr or older during 5.2 yr of treatment with conjugated estrogens 0.625 mg alone compared with placebo
- Unknown whether these findings apply to younger postmenopausal women
Breast Cancer
- The WHI estrogen plus progestin substudy also demonstrated an increased risk of invasive breast cancer
- In the absence of comparable data, these risks should be assumed to be similar for other doses of CE and MPA and other combinations and dosage forms of estrogens and progestins
- Because of these risks, estrogens with or without progestins should be prescribed at lowest effective dose and for shortest duration consistent with treatment goals and individual risks
Endometrial cancer
- Estrogens alone: There is an increased risk of endometrial cancer in a woman with a uterus who uses unopposed estrogens
- Adding a progestin to estrogen therapy has been shown to reduce the risk of endometrial hyperplasia, which may be a precursor to endometrial cancer
Contraindications
Hypersensitivity, including anaphylaxis or angioedema to estrogen/progestins Known protein C, protein S, or antithrombin deficiency, or other known thrombophilic disorders
Pregnancy
Estrogen-dependent neoplasia
Current/history of DVT/PE, arterial thromboembolic disease, breast cancer, liver disease/tumors
Undiagnosed abnormal vaginal bleeding
Cautions
Caution in patients with bone mineral density changes, current/history of depression, DM, HTN, hyperlipidemia, hypertriglyceridemia, obesity, endometriosis, family history of breast cancer & DVT/PE, smoking, epilepsy, migraine, renal/cardiac impairment; discontinue estrogen with or without progestogen, if DVT/PE, stroke or MI occur or suspected
Discontinue if the following develop: jaundice, visual problems, 4-6 wk before major surgery, any symptoms of VTE, massive BP increase, unusually severe migraines or first-time migraines, depression
The WHI estrogen plus progestin substudy reported increased risk (not statistically significant) of coronary heart disease (CHD) events (defined as nonfatal MI, silent MI, or CHD death) in women receiving daily CE plus MPA compared to women receiving placebo; an increase in relative risk was demonstrated in year 1, and a trend toward decreasing relative risk was reported in years 2 through 5; the WHI estrogen-alone substudy reported no overall effect on CHD events in women receiving estrogen-alone compared to placebo
Increased risk of post-op thromboembolic complications; if feasible, discontinue 4-6 wk before major surgery or the type associated with increased risk of thromboembolism, or during periods of prolonged immobilization
History of migraine with aura reported with therapy
In some epidemiologic studies, use of estrogen plus progestin and estrogen-only products, in particular for 5 or more years, has been associated with increased risk of ovarian cancer; however, duration of exposure associated with increased risk is not consistent across all epidemiologic studies and some report no association
Estrogen administration may lead to severe hypercalcemia in patients with breast cancer and bone metastases; if hypercalcemia occurs, use of the drug should be stopped and appropriate measures taken to reduce serum calcium levels
Angioedema involving eye/eyelid, face, larynx, pharynx, tongue and extremity (hands, legs, ankles, and fingers) with or without urticaria requiring medical intervention has occurred in postmarketing; women who develop angioedema anytime during course of treatment should not receive it again; exogenous estrogens may exacerbate symptoms of angioedema in women with hereditary angioedema; consider whether benefits of estrogen therapy outweigh risks in such women
Cases of anaphylactic/ anaphylactoid reactions, which developed anytime during course of treatment and required emergency medical management, reported in postmarketing setting
In women with preexisting hypertriglyceridemia, estrogen therapy may be associated with elevations of plasma triglycerides leading to pancreatitis; consider discontinuation of treatment if pancreatitis occurs
Although transdermally administered estrogen therapy avoids first-pass hepatic metabolism, estrogens may be poorly metabolized in women with impaired liver function; for women with a history of cholestatic jaundice associated with past estrogen use or with pregnancy, caution should be exercised and in the case of recurrence, medication should be discontinued
Estrogen administration leads to increased thyroid-binding globulin (TBG) levels; women dependent on thyroid hormone replacement therapy who are also receiving estrogens may require increased doses of thyroid replacement therapy; these women should have their thyroid function monitored in order to maintain their free thyroid hormone levels in an acceptable range
Estrogens plus progestins may cause some degree of fluid retention; women with conditions that might be influenced by this factor, such as cardiac or renal impairment warrant careful observation when estrogens plus progestins are prescribed; discontinue estrogen plus progestogen therapy, with evidence of medically concerning fluid retention; certain conditions may become exacerbated by fluid retention (eg, asthma, migraine, cardiac/renal dysfunction, epilepsy)
Estrogen therapy should be used with caution in women with hypoparathyroidism as estrogen-induced hypocalcemia may occur
For women known to have residual endometriosis post-hysterectomy, the addition of progestin should be considered; malignant transformation of residual endometrial implants reported in women treated post-hysterectomy with estrogen-alone therapy
Estrogen therapy may cause exacerbation of asthma, diabetes mellitus, epilepsy, migraine or porphyria, systemic lupus erythematosus, and hepatic hemangiomas and should be used with caution in women with these conditions; consider whether benefits of estrogen therapy outweigh risks in such women
Manage appropriately any risk factors for arterial vascular disease (for example, hypertension, diabetes mellitus, tobacco use, hypercholesterolemia, and obesity) and/or venous thromboembolism (VTE), including personal history or family history of VTE, obesity, and systemic lupus erythematosus
Do not use with conditions that predispose to hyperkalemia
A 2 to 4-fold increase in risk of gallbladder disease requiring surgery in postmenopausal women receiving estrogens reported
Retinal vascular thrombosis reported in patients receiving estrogens; discontinue medication pending examination if there is sudden partial or complete loss of vision, or a sudden onset of proptosis, diplopia, or migraine; if examination reveals papilledema or retinal vascular lesions, estrogens should be discontinued
There are, possible risks that may be associated with use of progestins with estrogens compared to estrogen-alone regimens, including a possible increased risk of breast cancer, adverse effects on lipoprotein metabolism (e.g., lowering HDL, raising LDL), and impairment of glucose tolerance
All women should receive yearly breast examinations by a healthcare provider and perform monthly breast self-examinations; in addition, mammography examinations should be scheduled based on patient age, risk factors, and prior mammogram results; the use of estrogen-alone and estrogen plus progestin therapy reported to result in increase in abnormal mammograms requiring further evaluation
Use caution in individuals with severe hypocalcemia; consider whether benefits of estrogen therapy outweigh risks in such women
Endometrial Cancer
- Studies of addition of progestin for 10 or more days of cycle of estrogen administration, or daily with estrogen in a continuous regimen, have reported lowered incidence of endometrial hyperplasia than would be induced by estrogen treatment alone
- Increased risk of endometrial cancer has been reported with the use of unopposed estrogen therapy in a woman with a uterus; the reported endometrial cancer risk among unopposed estrogen users is about 2- to 12- fold greater than in nonusers, and appears dependent on duration of treatment and on estrogen dose
- Most studies show no significant increased risk associated with use of estrogens for less than 1 year; the greatest risk appears to be associated with prolonged use, with increased risks of 15- to 24-fold for 5 to 10 years or more
- This risk has been shown to persist for at least 8 to 15 years after estrogen therapy is discontinued
- Perform adequate diagnostic measures, including directed or random endometrial sampling when indicated, to rule out malignancy in postmenopausal women with undiagnosed persistent or recurring abnormal genital bleeding with unknown etiology
- There is no evidence that the use of natural estrogens results in a different endometrial risk profile than synthetic estrogens of equivalent estrogen dose; adding a progestogen to estrogen therapy in postmenopausal women has been shown to reduce the risk of endometrial hyperplasia, which may be a precursor to endometrial cancer
Drug interaction overview
- In-vitro and in-vivo studies have shown that estrogens are metabolized partially by cytochrome P450 3A4 (CYP3A4); therefore, inducers or inhibitors of CYP3A4 may affect estrogen drug metabolism
- Inducers of CYP3A4 such as St. John’s wort (Hypericum perforatum) preparations, phenobarbital, carbamazepine, and rifampin may reduce plasma concentrations of estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile
- Inhibitors of CYP3A4 such as erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir and grapefruit juice may increase plasma concentrations of estrogens and result in adverse reactions
- Drugs or herbal products that induce or inhibit cytochrome P-450 enzymes, including CYP3A4, may decrease or increase the serum concentrations of norethindrone
Pregnancy & Lactation
Pregnancy
Not indicated for use in pregnancy; there are no data with use of in pregnant women; however, epidemiologic studies and meta-analyses have not found an increased risk of genital or nongenital birth defects (including cardiac abnormalities and limb-reduction defects) following exposure to combined hormonal contraceptives (estrogen and progestins) before conception or during early pregnancy
Lactation
Estrogens plus progestogens are present in human milk and can reduce milk production in breastfeeding women; this reduction can occur at any time but is less likely to occur once breastfeeding is well established; the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for therapy and any potential adverse effects on the breastfed child from therapy or from underlying maternal condition
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Estradiol: Endogenous estrogen; reduces the release of gonadotropin-releasing hormone from hypothalamus, reduces release of LH and FSH from pituitary gland; increases synthesis of DNA, RNA, and various proteins in target tissues. Estrogen replacement reduces elevated levels of estrogen and progesterone LH and FSH in postmenopausal women.
Norethindrone acetate: Progestin; inhibits secretion of gonadotropins from pituitary gland; prevents follicular maturation and ovulation, stimulates growth of mamary tissues
Pharmacokinetics
Peak Plasma Time: Estradiol: 5-8 hr (PO); norethindrone: 1-2 hr (PO)
Protein Bound: Estradiol: 98%, norethindrone: 90-97%
Bioavailability: Estradiol (50%); norethindrone (100%)
Metabolism
- Estradiol: liver, undergoes extensive first-pass metabolism
- Norethindrone: Liver
Half-Life
- Estradiol: 12-14 hr (PO), 2-3 hr (patch)
- Norethindrone: 8-11 hr (PO), 6-8 hr (patch)
Metabolites
- Estradiol: estriol, estrone
- Norethindrone: sulfate, glucuronide (inactive)
Excretion
- Estradiol: urine as conjugates, most estrogens are also excreted in the bile and undergo enterohepatic recycling
- Norethindrone: Urine 33-81%; Feces 35-43%
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Formulary
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