Dosing & Uses
Dosage Forms & Strengths
Benign Prostatic Hyperplasia
1 capsule PO 30 min after same meal once daily
Swallow capsule whole; do not chew, crush, or split
Serious - Use Alternative
Significant - Monitor Closely
Ejaculation disorders (10%)
Breast enlargement/tenderness (3%)
Decreased libido (4.5%)
Breast disorders (1%)
Prostate cancer (high grade)
- Immune system disorders: Hypersensitivity reactions, including rash, pruritus, urticaria, localized edema, serious skin reactions, and angioedema
- Neoplasms: Male breast cancer
- Psychiatric disorders: Depressed mood
- Reproductive system and breast disorders: Testicular pain and testicular swelling
- Immune system disorders: Hypersensitivity reactions, including rash, urticaria, pruritus, angioedema, and respiratory problems have been reported with positive rechallenge in some cases
- Cardiac disorders: Palpitations, dyspnea, atrial fibrillation, arrhythmia, and tachycardia
- Skin disorders: Skin desquamation, including Stevens-Johnson syndrome
- Gastrointestinal disorders: Constipation, vomiting
- Reproductive system and breast disorders: Priapism
- Vascular disorders: Hypotension
- Ophthalmologic disorders: During cataract surgery, a variant of small pupil syndrome known as intraoperative floppy iris syndrome (IFIS) associated with alpha adrenergic antagonist therapy
Previously demonstrated, clinically significant hypersensitivity (eg, serious skin reactions, angioedema, urticaria, pruritus, respiratory symptoms) to dutasteride, other 5 alpha-reductase inhibitors, or tamsulosin
Pregnancy and women of childbearing potential should not take or handle drug
Prior to initiating treatment, rule out other urological conditions
Orthostatic hypotension and/or syncope can occur
Reduces total serum prostate-specific antigen (PSA) concentration by ~50%, evaluate any confirmed increases in PSA levels from nadir, even if those values are within normal range, for the presence of prostate cancer
Caution patients about the possibility and seriousness of priapism
Advise patients to not donate blood until 6 months after their last dose
Intraoperative floppy iris syndrome has been observed during cataract surgery after alpha-adrenergic antagonist exposure
Metabolized by both CYP3A4 and CYP2D6; concomitant use with known inhibitors can cause a marked increase in plasma levels resulting in an increased incidence of adverse effects; do not use with strong 3A4 or 2D6 inhibitors (eg, ketoconazole, paroxetine); exercise caution when coadministered with less potent inhibitors (eg, terbinafine, erythromycin)
Coadministration with PDE-5 inhibitors (eg, sildenafil) can increase risk of hypotension
Coadministration with other alpha-antagonists (eg, doxazosin, terazosin) may cause additive hypotension
Limited studies showed inconclusive results regarding coadministration of tamsulosin with warfarin (monitor INR)
5-ARIs and prostate cancer risk
- June 9, 2011: Recent data from 2 large, randomized, controlled trials observed an increased risk of being diagnosed with a more serious form of prostate cancer (high-grade prostate cancer) in trial participants taking 5-alpha reductase inhibitors (5-ARIs)
- The 2 trials are the Prostate Cancer Prevention Trial (PCPT) and the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial
- The revised prescribing information recommends that prior to initiating therapy with 5-ARIs, perform appropriate evaluation to rule out other urological conditions, including prostate cancer, that might mimic benign prostatic hyperplasia (BPH)
Pregnancy & Lactation
Pregnancy Category: X
Lactation: Unknown whether distributed in breast milk, contraindicated in breastfeeding women
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.
Mechanism of Action
Dutasteride: Selective inhibitor of type 1 and type 2 isoforms of 5-alpha-reductase
Tamsulosin: Alpha-adrenergic antagonist; blocks alpha-1a adrenergic receptor in smooth muscle of prostate, decreasing bladder neck & urethral resistance
Bioavailability: 60% (dutasteride); 10% (tamsulosin)
Peak Plasma Time: 2-3 hr (dutasteride); 4-5 hr fasting; 6-7 hr with food (tamsulosin)
Onset: 1-2 weeks (dutasteride); 4-8 hr (tamsulosin)
Protein Bound: 99% (dutasteride and tamsulosin)
Vd: 300-500 L (dutasteride); 0.2 L (tamsulosin)
- Metabolism: hepatic P450 enzyme CYP3A4 and CYP2D6
- Metabolites, major: 4'-hydroxydutasteride, 6-hydroxydutasteride (as active as parent), 6,4'-dihydroxydutasteride
- Metabolism: liver
- Metabolites: glucuronide and sulfate conjugates (inactive)
Half-Life: 5 weeks at steady state (dutasteride); 14-15 hr (tamsulosin)
Excretion: mainly feces (dutasteride); urine 76%, feces 21% (tamsulosin)
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The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.
|1||This drug is available at the lowest co-pay. Most commonly, these are generic drugs.|
|2||This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.|
|3||This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.|
|4||This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.|
|5||This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.|
|6||This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.|
|NC||NOT COVERED – Drugs that are not covered by the plan.|
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Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.