Dosing & Uses
Dosage Forms & Strengths
tablet
- 50mg
Hyperthyroidism
300-450 mg/day PO divided q8hr initially (may require up to 600-900 mg/day)
Maintenance: 100-150 mg/day divided q8hr
Thyrotoxic Crisis (Off-label)
Initial 200-300 mg PO q4-6hr initially on Day 1 (may require 800-1200 mg/day), then reduce gradually; some practitioners propose an initial dose of 600-1000 mg with gradual dose reduction after initial response
Maintenance: 100-150 mg/day PO divided q8-12hr
Graves Disease
50-150 mg PO q8hr initially
Maintenance: 50 mg PO q8-12hr for up to 12-18 months; then taper and discotinue if euthyroidism restored (TSH) is normal
Renal Impairment
Dose adjustment not necessary
Other Indications & Uses
Off-label: alcoholic liver disease
Dosage Forms & Strengths
tablet
- 50mg
Hyperthyroidism
Neonates (<28 days old): 5-10 mg/kg/day PO divided q8hr initially
<6 years: 5-7 mg/kg/day PO divided q8hr initially OR
6-10 years: 50-150 mg/day PO divided q8hr
>10 years: 150-300 mg/day
Maintenance: Usually 1/3-2/3 of intial dose based on response divided q8-12hr
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
Contraindicated (1)
- sodium iodide I-131
propylthiouracil will decrease the level or effect of sodium iodide I-131 by Other (see comment). Contraindicated. Discontinue antithyroid medications at least 3-4 days before administering sodium iodide I-131 and do not coadminister; thyroid agents decrease update of sodium iodide I-131 by the thyroid gland
Serious - Use Alternative (7)
- carbamazepine
propylthiouracil, carbamazepine. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased risk of agranulocytosis.
- clozapine
propylthiouracil, clozapine. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased risk of agranulocytosis.
- macimorelin
propylthiouracil, macimorelin. unspecified interaction mechanism. Avoid or Use Alternate Drug. Drugs that may blunt the growth hormone (GH) response to macrimorelin may impact the accuracy of the diagnostic test. Allow sufficient washout time of drugs affecting GH release before administering macimorelin.
- methimazole
propylthiouracil, methimazole. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased risk of agranulocytosis.
- pexidartinib
propylthiouracil and pexidartinib both increase Other (see comment). Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.
- pretomanid
propylthiouracil, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.
- ropeginterferon alfa 2b
ropeginterferon alfa 2b, propylthiouracil. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Myelosuppressive agents can produce additive myelosuppression. Avoid use and monitor patients receiving the combination for effects of excessive myelosuppression.
Monitor Closely (15)
- antithrombin alfa
propylthiouracil decreases effects of antithrombin alfa by pharmacodynamic antagonism. Use Caution/Monitor.
- antithrombin III
propylthiouracil decreases effects of antithrombin III by pharmacodynamic antagonism. Use Caution/Monitor.
- argatroban
propylthiouracil decreases effects of argatroban by pharmacodynamic antagonism. Use Caution/Monitor.
- bemiparin
propylthiouracil decreases effects of bemiparin by pharmacodynamic antagonism. Use Caution/Monitor.
- bivalirudin
propylthiouracil decreases effects of bivalirudin by pharmacodynamic antagonism. Use Caution/Monitor.
- dalteparin
propylthiouracil decreases effects of dalteparin by pharmacodynamic antagonism. Use Caution/Monitor.
- enoxaparin
propylthiouracil decreases effects of enoxaparin by pharmacodynamic antagonism. Use Caution/Monitor.
- fondaparinux
propylthiouracil decreases effects of fondaparinux by pharmacodynamic antagonism. Use Caution/Monitor.
- heparin
propylthiouracil decreases effects of heparin by pharmacodynamic antagonism. Use Caution/Monitor.
- lycopus
lycopus increases effects of propylthiouracil by pharmacodynamic synergism. Use Caution/Monitor. Lycopus blocks peripheral conversion of T4 to T3.
- phenindione
propylthiouracil decreases effects of phenindione by pharmacodynamic antagonism. Use Caution/Monitor.
- potassium iodide
potassium iodide, propylthiouracil. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Concomitant use with antithyroid drugs may potentiate the hypothyroid and goitrogenic effects of potassium iodide.
- protamine
propylthiouracil decreases effects of protamine by pharmacodynamic antagonism. Use Caution/Monitor.
- theophylline
propylthiouracil increases levels of theophylline by decreasing elimination. Use Caution/Monitor.
- warfarin
propylthiouracil decreases effects of warfarin by unspecified interaction mechanism. Use Caution/Monitor.
Minor (3)
- cadexomer iodine
cadexomer iodine, propylthiouracil. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive hypothyroid effects.
- iodinated glycerol
iodinated glycerol, propylthiouracil. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive hypothyroid effects.
- iodine
iodine, propylthiouracil. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive hypothyroid effects.
Adverse Effects
Frequency Not Defined
Agranulocytosis
Aplastic anemia
Dermatologic reactions
Hepatitis
Polyarthritis
Drowsiness
Fever
Headache
Vertigo
Alopecia
Erythema nodosum
Exfoliative dermatitis
Skin rash
Skin ulcers
Goiter
Weight gain
Constipation
Loss of taste
Granulopenia
Leukopenia
Thrombocytopenia
Postmarketing Reports
Inhibition of myelopoiesis (agranulocytosis, granulopenia, aplastic anemia, and thrombocytopenia)
Drug fever, a lupus-like syndrome (including splenomegaly and vasculitis)
Periarteritis
Hypoprothrombinemia
Bleeding
Nephritis
Glomerulonephritis
Interstitial pneumonitis
Exfoliative dermatitis
Erythema nodosum
Vasculitis syndrome associated with the presence of antineutrophilic cytoplasmic antibodies (ANCA) Skin rash
Uticaria
Nausea
Vomiting
Epigastric distress
Arthralgia
Paresthesias
Loss of taste
Taste perversion
Warnings
Black Box Warnings
Severe liver injury and acute liver failure, some of which have been fatal, have been reported in adult and pediatric patients taking propylthiouracil
Closely monitor for symptoms and signs of liver injury (eg, , anorexia, nausea, vomiting, fatigue, pruritus, dark colored urine, or jaundice), especially during first 6 months after initiating therapy
Reserve propylthiouracil use for those unable to tolerate other treatments (eg, methimazole, radioactive iodine, surgery)
Propylthiouracil may be the treatment of choice during and just before the first trimester of pregnancy (strong association of methimazole with congenital malformation during first trimester)
Contraindications
Hypersensitivity
Cautions
Risk of severe rare immunoallergenic hepatitis
Severe dermatologic reactions reported
Discontinue in presence of unexplained fever
Lupus-like syndrome reported (may need to discontinue)
Glomerulonephritis and interstitial nephritis with acute renal failure reported
Interstitial pneumonitis may occur
High relapse rate (more likely in smokers)
Agranulocytosis within first 3 months of therapy reported; instruct patients to immediately report any symptoms suggestive of agranulocytoses, such as fever or sore throat; leukopenia, thrombocytopenia, and aplastic anemia (pancytopenia) may also occur; discontinue treatment if agranulocytosis, aplastic anemia (pancytopenia) suspected, and patient's bone marrow indices obtained
Patients who receive therapy should be under close surveillance and counseled regarding necessity of immediately reporting any evidence of illness, particularly sore throat, skin eruptions, fever, headache, or general malaise; in such cases, white blood cell and differential counts should be obtained to determine whether agranulocytosis has developed; particular care should be exercised with patients who are receiving concomitant drugs known to be associated with agranulocytosis
Cases of vasculitis resulting in severe complications and death reported; cases of vasculitis include: glomerulonephritis, leukocytoclastic cutaneous vasculitis, alveolar/pulmonary hemorrhage, cerebral angiitis, and ischemic colitis; severe cases require treatment with corticosteroids, immunosuppressant therapy, and plasmapheresis; if vasculitis is suspected, discontinue therapy and initiate appropriate intervention
Propylthiouracil can cause hypothyroidism necessitating routine monitoring of TSH and free T4 levels with adjustments in dosing to maintain a euthyroid state; because drug readily crosses placental membranes, propylthiouracil can cause fetal goiter and cretinism when administered to a pregnant woman
Liver toxicity
- Patients should be instructed to report any symptoms of hepatic dysfunction (anorexia, pruritus, jaundice, light-colored stools, dark urine, right upper quadrant pain, etc.), particularly in first six months of therapy; when these symptoms occur, measurement should be made of liver function (bilirubin, alkaline phosphatase) and hepatocellular integrity (ALT/AST levels)
- Biochemical monitoring of liver function (bilirubin, alkaline phosphatase) and hepatocellular integrity (ALT, AST) not expected to attenuate risk of severe liver injury due to rapid and unpredictable onset
- Liver injury resulting in liver failure, liver transplantation, or death, reported with therapy in adult and pediatric patients
- No cases of liver failure reported with use of methimazole in pediatric patients; therapy not recommended for pediatric patients except when methimazole not well-tolerated and surgery or radioactive iodine therapy are not appropriate therapies
- Patients should be informed of risk of liver failure; patients should be instructed to report symptoms of hepatic dysfunction (anorexia, pruritus, right upper quadrant pain, etc.), particularly in first six months of therapy
- When symptoms occur, therapy should be discontinued immediately and liver function tests and ALT and AST levels obtained; discontinue immediately if abnormal LFTs (transmainase>3 times ULN)
Pregnancy & Lactation
Pregnancy Category: D
Lactation: distributed in breast milk, contraindicated by some sources (AAP Committee states compatible w/ nursing ; AAFP states safe for nursing)
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
Inhibits synthesis of thyroid hormone by blocking oxidation of iodine in thyroid gland; blocks synthesis of T4 and T3
Pharmacokinetics
Absorption: 75%
Duration: 12-24 hr
Half-life elimination: 1-2 hr, increase in ESRD
Vd: 0.4 L/kg
Protein Bound: 80-85%
Concentration (200-400 mg single dose): 6-9 mcg/mL
Peak plasma time: 1-2 hr
Peak plasma concentration: (200-400 mg single dose): 6-9 mcg/mL
Metabolism: liver, to glucuronide conjugates, inorganic sulfates, sulfur metabolites
Total body clearance: 7 L/hr
Excretion: Urine (35%)
Images
| BRAND | FORM. | UNIT PRICE | PILL IMAGE |
|---|---|---|---|
| propylthiouracil oral - | 50 mg tablet |  | |
| propylthiouracil oral - | 50 mg tablet |  | |
| propylthiouracil oral - | 50 mg tablet |  | |
| propylthiouracil oral - | 50 mg tablet |  |
Copyright © 2010 First DataBank, Inc.
Patient Handout
propylthiouracil oral
PROPYLTHIOURACIL - ORAL
(PROE-pil-THYE-oh-URE-a-sil)
COMMON BRAND NAME(S): Propacil
WARNING: Propylthiouracil has rarely caused very serious (possibly fatal) liver disease, especially during the first 6 months of treatment. Stop taking propylthiouracil and tell your doctor right away if you develop symptoms of liver disease, including nausea/vomiting that doesn't stop, severe stomach/abdominal pain, dark urine, yellowing eyes/skin.
USES: Propylthiouracil is used to treat overactive thyroid (hyperthyroidism). It works by stopping the thyroid gland from making too much thyroid hormone.This medication is not recommended for use in children.
HOW TO USE: Read the Medication Guide provided by your pharmacist before you start taking propylthiouracil and each time you get a refill. If you have any questions, ask your doctor or pharmacist.Take this medication by mouth with or without food as directed by your doctor, usually 3 times a day (every 8 hours).Dosage is based on your medical condition and response to treatment.Take this medication exactly as directed. Do not increase your dose or take it more often than prescribed. Your condition will not improve faster, and your risk of side effects will increase.Use this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day. Do not stop taking this medication without consulting your doctor.Tell your doctor if your condition does not improve or if it worsens.
SIDE EFFECTS: Stomach upset, nausea, vomiting, mild rash/itching, or headache may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if you have any serious side effects, including: muscle/joint pain, signs of kidney problems (such as change in the amount of urine, bloody/dark urine), coughing up blood, shortness of breath.This medication may rarely cause very serious blood disorders (such as a low number of red cells, white cells, and platelets), especially during the first few months of treatment. Tell your doctor right away if you develop any of the following symptoms: signs of infection (such as sore throat that doesn't go away, fever), easy bruising/bleeding, unusual tiredness.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
PRECAUTIONS: Before taking propylthiouracil, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: blood disorders (such as agranulocytosis, thrombocytopenia), liver disease.Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).This medication should be used only when clearly needed during the first 3 months of pregnancy. It is not recommended for use during the last 6 months of pregnancy. Your doctor may direct you to use another medication during that time. Discuss the risks and benefits with your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, contact your doctor right away.This medication passes into breast milk. Consult your doctor before breast-feeding.
DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: "blood thinners" (such as warfarin), digoxin.
OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.
NOTES: Do not share this medication with others.Lab and/or medical tests (such as complete blood counts, liver/thyroid function, prothrombin time) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.
MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.
STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised November 2022. Copyright(c) 2023 First Databank, Inc.
IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.
Formulary
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