Propylthiouracil

INTRODUCTION

Indications

Palliative treatment of hyperthyroidism. Adjunct in the control of hyperthyroidism in preparation for thyroidectomy or radioactive iodine therapy.

Action

Inhibits the synthesis of thyroid hormones. Therapeutic Effects: ↓ signs and symptoms of hyperthyroidism.

Adverse Reactions/Side Effects

CNS: drowsiness, headache, vertigo. GI: nausea, vomiting, diarrhea, drug-induced hepatitis, loss of taste. Derm: rash, skin discoloration, urticaria. Endo: hypothyroidism. Hemat: AGRANULOCYTOSIS, leukopenia, thrombocytopenia. MS: arthralgia. Misc: fever, lymphadenopathy, parotitis.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Monitor signs of agranulocytosis and leukopenia (fever, sore throat, mucosal lesions, signs of infection) and thrombocytopenia (bruising, nose bleeds, bleeding gums). Report these signs to the physician immediately.

• Monitor and report signs of excessive or inadequate dosing. Inadequate doses of propylthiouracil mimic hyperthyroidism, as indicated by nervousness, weight loss, muscle wasting, tachycardia, and heat intolerance. Excessive doses mimic hypothyroidism, as indicated by lethargy, weight gain, bradycardia, and cold intolerance.

• Assess vertigo that might affect gait, balance, and other functional activities. Report balance problems and functional limitations to the physician, and caution the patient and family/caregivers to guard against falls and trauma.

• Assess any joint pain to rule out musculoskeletal pathology; that is, try to determine if pain is drug induced rather than caused by anatomic or biomechanical problems.

Interventions

• Use caution during aerobic exercise and endurance conditioning in patients with symptoms of hyperthyroidism because of the risk of arrhythmias. Assess heart rate and exercise tolerance frequently, and terminate exercise immediately if any untoward responses occur (See Appendix L).

• Guard against falls and trauma. Implement fall-prevention strategies (See Appendix E), especially if patient exhibits vertigo or other impairments that affect gait and balance.

Patient/Client-Related Instruction

• Advise patient about the likelihood of GI reactions such as nausea, vomiting, diarrhea, loss of taste, and inflammation of the salivary glands (parotitis). Instruct patient to report severe or prolonged GI problems, or signs of drug-induced hepatitis (yellow skin or eyes, abdominal pain, severe nausea and vomiting, fever, sore throat, malaise, weakness, facial edema).

• Instruct patient to report other troublesome side effects including severe or prolonged headache, fever, swollen lymph nodes, or skin reactions (rash, hives, discoloration).

Pharmacokinetics

Absorption: Rapidly absorbed from the GI tract.

Distribution: Concentrates in the thyroid gland; crosses the placenta and enters breast milk in low concentrations.

Metabolism and Excretion: Metabolized by the liver.

Half-life: 1–2 hr.