propylthiouracil

REMS

Graves' disease with hyperthyroidism or toxic multinodular goiter in patients who are intolerant to methimazole and for whom surgery or radioactive iodine therapy is not appropriate.
Adjunct in the control of hyperthyroidism in preparation for thyroidectomy or radioactive iodine therapy in patients who are intolerant to methimazole.

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity.

Use Cautiously in:

↓bone marrow reserve;
OB: May be used during 1st trimester (consider using methimazole during 2nd and 3rd trimesters); however, fetus may develop thyroid problems; mother and fetus may be at ↑ risk for hepatotoxicity;
Geri: Older adults may have ↑ sensitivity to the drug's effect; initiate therapy with lowest dose;
Pedi: Children <6 yr (safety and effectiveness not established); not recommended unless methimazole not tolerated and surgery or radioactive iodine therapy not appropriate.

Adv. Reactions/Side Effects ⬆ ⬇

CV: edema, vasculitis

Derm: rash, exfoliative dermatitis, hair loss, skin discoloration, STEVENS-JOHNSON SYNDROME, TOXIC EPIDERMAL NECROLYSIS, urticaria

EENT: parotitis

Endo: hypothyroidism

GI: nausea, vomiting, diarrhea, HEPATOTOXICITY, loss of taste, splenomegaly

GU: glomerulonephritis

Hemat: AGRANULOCYTOSIS, APLASTIC ANEMIA, BLEEDING, leukopenia, thrombocytopenia

MS: arthralgia, myalgia

Neuro: drowsiness, headache, paresthesia, vertigo

Resp: interstitial pneumonitis

Misc: fever, lymphadenopathy

Interactions ⬆ ⬇

Drug-drug:

Additive bone marrow depression with antineoplastics or radiation therapy.
Additive antithyroid effects with lithium, or potassium iodide.
↑risk of agranulocytosis with phenothiazines.

Availability ⬆ ⬇

(Generic available)

Tablets: 50 mg

Route/Dosage ⬆ ⬇

PO (Adults ): 100 mg every 8 hr; may be ↑ to 400 mg/day (occasional patient may require 600–900 mg/day); usual maintenance dose = 100–150 mg/day.
PO (Children >10 yr): 50–300 mg/day given once daily or in 2–4 divided doses.
PO (Children 6–10 yr): 50–150 mg/day given once daily or in 2–4 divided doses.

Action ⬆ ⬇

Inhibits the synthesis of thyroid hormones.

Therapeutic effects:

Decreased signs and symptoms of hyperthyroidism.

Classifications ⬆ ⬇

Therapeutic Classification: antihyroid agents

Pharmacologic Classification: thioamides

Pharmacokinetics ⬆ ⬇

Absorption: Rapidly absorbed from the GI tract.

Distribution: Concentrates in the thyroid gland.

Metabolism/Excretion: Metabolized by the liver. Primarily excreted in the urine as metabolites.

Half-Life: 1–2 hr.

Canadian Brand Names ⬆ ⬇

Time/Action Profile ⬆ ⬇

(effects on clinical thyroid status)

ROUTE	ONSET	PEAK	DURATION
PO	10–21 days‡	6–10 wk	wk

‡Effects on serum thyroid hormone concentration may occur within 60 min of a single dose.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take medication exactly as directed, around the clock. If a dose is missed, take as soon as remembered; take both doses together if almost time for next dose; check with health care professional if more than 1 dose is missed. Consult health care professional prior to discontinuing medication.
Instruct patient to monitor weight 2–3 times weekly. Report significant changes.
May cause drowsiness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known.
Advise patient to consult health care professional regarding dietary sources of iodine (iodized salt, shellfish).
Advise patient to report sore throat, fever, chills, headache, malaise, weakness, yellowing of eyes or skin, unusual bleeding or bruising, symptoms of hyperthyroidism or hypothyroidism, or rash to health care professional promptly.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
Advise patient to carry identification describing medication regimen at all times and to notify health care professional of medication regimen prior to treatment or surgery.
Rep: Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.
Emphasize the importance of routine exams to monitor progress and to check for side effects.

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Indications ⬇