d routes:Severe hypothyroidism•Adult: PO 0.025-0.1 mg qd, increased by 0.05-0.1 mg q1-4 wk until desired response, maintenance dose 0.1-0.4 mg qd•Child: PO 0.01-0.05 qd, may increase 0.025-0.05 mg q1-4 wk until desired responseMild hypothyroidism•Initial 50 mg qd; increase by 25-50 mg at interval of 2-4 wkCretinism•Child: IV 0.025-0.05 mg qd, may increase by 0.05-0.1 mg PO q2-3wkMyxedema coma•Adult: IV 0.2-0.5 mg, may increase by 0.1-0.3 mg after 24 hr; place on oral medication as soon as possibleAvailable forms: Inj IV 200, 500 mg/vial; tabs 0.025, 0.05, 0.075, 0.088 mg, 0.1, 0.112 mg, 0.125, 0.15, 0.175, 0.2, 0.3 mgSide effects/adverse reactions:CNS: Anxiety, insomnia, tremors, headache, thyroid stormCV: Tachycardia, palpitations, angina, dysrhythmias, hypertension, cardiac arrestGI: Nausea, diarrhea, increased or decreased appetite, crampsMISC: Menstrual irregularities, weight loss, sweating, heat intolerance, feverContraindications: Adrenal insufficiency, myocardial infarction, thyrotoxicosisPrecautions: Elderly, angina pectoris, hypertension, ischemia, cardiac disease, pregnancy (A), lactationPharmacokinetics:IV/PO: Peak 12-48 hr, half-life 6-7 days; distributed throughout body tissuesInteractions/incompatibilities:•Decreased absorption of levothyroxine: cholestyramine•Increased effects of: anticoagulants, sympathomimetics, tricyclic antidepressants•Decreased effects of: digitalis drugs, insulin, hypoglycemics•Decreased effects of levothyroxine: estrogens•Considered to be incompatible in syringe with all other drugsLab test interferences:Increase: CPK, LDH, AST, PBI, blood glucoseDecrease: TSH, 131I uptake test, uric acid, triglyceridesNURSING CONSIDERATIONSAssess:•B/P, pulse before each dose•I&O ratio•Weight qd in same clothing, using same scale, at same time of day•Height, growth rate if given to a child•T3, T4, FTIs, which are decreased; ra...
