Thyroid And Antithyroid Drugs Flashcards
(22 cards)
What are the drugs for hyperthyroidism?
Antithyroid drugs: thioamides, potassium iodide
Radioactive iodine
Adjunctive drugs: beta blockers, calcium channels blockers, corticosteroids
What are the drugs for hypothyroidism?
Levothyroxine, liothyronine
What are the causes of hyperthyroidism?
Grave’s disease- most common
Too much iodine
Over medication with synthetic thyroid hormone
What are the manifestations of hyperthyroidism?
Hot, heat intolerance Moist skin, thin air Retraction of eye lids with wide stare Exophthalmos Tachycardia, heart failure, arrhythmia Nervousness
What are the thioamides drugs?
Methimazole
Propylthiouracil (PTU)
What are the MOA of the thioamides?
Prevent thyroid hormone synthesis by inhibiting iodination and coupling reactions
PTU also inhibits conversion of T4 to T3
Slow onset: takes 3-4 weeks to deplete stored T4
What are the pharmacokinetics and pharmacodynamics of the thioamides?
Methimazole- 10 times more potent and longer half life(6h) than PTU(1.5hr)
Methimazole: oral once a day
PTU: oral every 8 hrs
What are the clinical use of the methimazole?
Drug treatment f choice for treatment of hyperthyroidism
What is the clinical use of PTU?
Preferred during the 1st trimester of pregnancy
Drug of choice for thyroid storm due to inhibition of conversion of T4 to T3
For those having adverse reactions to methimazole
What are the adverse effects of The Thioamides?
Hepatic toxicity (PTU>>) Hepatic failure Liver function closely monitored especially with PTU
What is the MOA of potassium iodide?
Inhibit thyroid hormone release and synthesis
Transient effect due to escapability of gland
What is the clinical use of the potassium iodide?
Decreases the size and vascularity of thyroid gland before surgery (7-10 days tx)
Inhibits uptake of radioactive iodine: protects gland from damage
What are the adverse effects of the potassium iodide?
Unpleasant taste, gastritis
Salivary gland inflammation
Conjunctivitis
What is the MOA of RAI?
Causes destruction of parenchymal cells in the thyroid
What is the clinical use of RAI?
Definitive therapy for hyperthyroidism
Has a permanent effect
May be used after patients are treated with thioamides to become euthyroid
What are the precautions and contraindications of RAI?
Patients must be capable of following radiation safety procedures
Do not use in pregnant or nursing women
What are the adverse effects of RAI?
Permanent hypothyroidism in most patients(90%)
Monitor thyroid function and initiate levothyroxine if necessary
What are the clinical uses of the adjunct therapies?
Propanolol- reduces conversion of T4 to T3
CCB (Diltiazem, Verapamil)- patients with beta blockers contraindications (asthma patients)
Corticosteroids- reduce conversion of T4 to T3, inhibits TSH secretion
What are the major causes of hypothyroidism?
Hashimoto’s disease
Surgical removal
Radiation treatment
What are the manifestations of hypothyroidism?
Cold intolerance Pale, dry skin Lethargy fatigue Weight gain Decrease metabolic rate
What is the clinical use of levothyroxine?
Hypothyroidism
Cretinism- to prevent irreversible mental retardation in newborns
Myxedema coma
TSH suppression therapy
What are the adverse effects of levothyroxine?
May produce symptoms of hyperthyroidism
