Thyrar

Thyrar,

trademark for thyroid hormone.

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thyroid, desiccated

Armour Thyroid, Thyrar, Thyroid Strong, Westhroid

Pharmacologic class: Hormone supplement

Therapeutic class: Thyroid hormone

Pregnancy risk category A

FDA Boxed Warning

• Drug shouldn't be used alone or with other agents to treat obesity or weight loss. In euthyroid patients, doses within range of daily hormonal requirements are ineffective for weight loss. Larger doses may cause serious or life-threatening toxicity, particularly when given with sympathomimetic amines (such as those used for anorectic effects).

Action

Regulates cell growth and differentiation and increases metabolic rate of body tissues; effects mediated at cellular level

Availability

Tablets: 15 mg, 30 mg, 60 mg, 90 mg, 120 mg, 180 mg, 240 mg, 300 mg

⊘Indications and dosages

➣ Mild hypothyroidism

Adults: Initially, 60 mg/day P.O.; may increase by 60 mg q 30 days to desired response. Usual maintenance dosage is 60 to 180 mg/day.

➣ Severe hypothyroidism

Adults: Initially, 15 mg/day P.O. daily; may increase to 30 mg/day after 2 weeks and then to 60 mg/day 2 weeks later. Assess after 1 month, and again 1 month later at 60 mg-dose. If necessary, dosage may then increase to 120 mg/day P.O. for 2 months, with assessment repeated. Subsequent assessments and dosage increases may occur up to a maximum of 180 mg/day.

➣ Congenital or severe hypothyroidism

Children: Initially, 15 mg P.O. daily; may increase to 30 mg/day after 2 weeks, with subsequent increases at 2-week intervals. Maintenance dosage may be higher in growing children than in hypothyroid adults.

Dosage adjustment

• Cardiovascular disease
• Elderly patients

Contraindications

• Hypersensitivity to drug or its components
• Adrenal insufficiency
• Thyrotoxicosis

Precautions

Use cautiously in:
• tartrazine sensitivity (some products)
• cardiovascular disease
• elderly patients
• breastfeeding patients.

Administration

• Give before breakfast each day.

Route	Onset	Peak	Duration
P.O.	Unknown	12-48 hr	Unknown

Adverse reactions

CNS: insomnia, tremors, headache

CV: palpitations, angina pectoris, hypertension, tachycardia, arrhythmias, cardiac arrest

GI: nausea, vomiting, diarrhea

GU: menstrual irregularities

Metabolic: heat intolerance, thyroid storm

Musculoskeletal: accelerated bone maturation (in children)

Skin: sweating

Other: weight loss, appetite changes, fever

Interactions

Drug-drug. Anticoagulants, catecholamines, sympathomimetics: increased effects of these drugs

Bile acid sequestrants: decreased thyroid hormone absorption

Digoxin, insulin, oral hypoglycemics: decreased effects of these drugs

Estrogen: decreased thyroid hormone effects

Oral anticoagulants: increased risk of bleeding

Drug-diagnostic tests. Aspartate aminotransferase, creatine kinase, glucose, lactate dehydrogenase, protein-bound iodine: increased levels

Thyroid function tests: decreased values

Drug-herbs. Bugleweed, soy: increased adverse drug reactions

Patient monitoring

☞ Monitor for chest pain. If it occurs, withhold drug and contact prescriber.
• Assess vital signs and temperature frequently.
☞ Monitor thyroid function tests closely. Immediately report evidence of thyroid storm.
• In diabetic patient, monitor blood glucose level closely.
• In children, monitor sleeping pulse rate and morning basal temperature.
• In female on long-term therapy, monitor bone density tests.

Patient teaching

• Tell patient to take each morning before breakfast.
☞ Caution patient not to stop therapy abruptly. Dosage must be tapered.
☞ Advise patient to immediately report chest pain or signs and symptoms of drug toxicity (fever, chest pain, rapid pulse, skipped heartbeats, heat intolerance, excessive sweating, nervousness, emotional instability).
• Instruct patient to tell all prescribers he's taking drug. Caution him not to use over-the-counter preparations without consulting prescriber.
• Tell diabetic patient that drug may alter blood glucose level. Encourage frequent glucose self-monitoring.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and herbs mentioned above.