PTU

PTU

abbr.

propylthiouracil

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PTU

propylthiouracil.

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propylthiouracil (PTU)

Propyl-Thyracil (CA)

Pharmacologic class: Thioamide derivative

Therapeutic class: Antithyroid agent

Pregnancy risk category D

Action

Directly interferes with thyroid synthesis by preventing iodine from combining with thyroglobulin, leading to decreased thyroid hormone levels

Availability

Tablets: 50 mg

⊘Indications and dosages

➣ Hyperthyroidism

Adults: Initially, 300 to 450 mg P.O. daily in equally divided doses q 8 hours; for maintenance, 100 to 150 mg P.O. daily.

➣ Thyrotoxic crisis

Adults: 200 mg P.O. q 4 to 6 hours during first 24 hours, then a maintenance dosage of 100 to 150 mg P.O. daily

Contraindications

• Hypersensitivity to drug
• Pregnancy and breastfeeding

Precautions

Use cautiously in:
• decreased bone marrow reserve.

Administration

• Give with meals to reduce GI upset.

Route	Onset	Peak	Duration
P.O.	Unknown	1-1.5 hr	Unknown

Adverse reactions

CNS: drowsiness, headache, vertigo, neuritis, paresthesia

GI: nausea, vomiting, diarrhea, epigastric distress

Hematologic: agranulocytosis, leukopenia, thrombocytopenia

Hepatic: jaundice, hepatic necrosis

Metabolic: hypothyroidism

Musculoskeletal: joint pain, myalgia

Skin: rash, urticaria, pruritus, skin discoloration, alopecia, cutaneous vasculitis

Other: taste loss, fever, lymphadenopathy, parotitis, edema

Interactions

Drug-drug. Anticoagulants: potentiation of anticoagulant effect

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, bilirubin, lactate dehydrogenase: increased levels

Granulocytes, platelets: decreased levels

Prothrombin time: prolonged

Patient monitoring

• Monitor CBC and liver and thyroid function tests.
• Assess for signs and symptoms of hypothyroidism (cold intolerance, nonpitting edema, fatigue, weight gain, and depression).
☞ Monitor for severe rash, fever, or enlarged cervical lymph nodes. If present, stop therapy and notify prescriber.

Patient teaching

• Instruct patient to take with meals to reduce GI upset.
• Teach patient to recognize and report signs and symptoms of hypothyroidism and jaundice.
• Advise patient to discuss iodine intake (as in iodized salt and shellfish) with prescriber.
• Tell patient to avoid over-the-counter cold remedies that contain iodine.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• Advise female patient of childbearing age to discuss pregnancy or breastfeeding with prescriber before taking.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.