Pharmacology Mnemonics - Flash Cards

Name: Iodide

Class: Antithyroid drug

Mechanism: High doses of iodide inhibit thyroid gland fxn. Effects decrease w/time, possible due to decrease in iodide transport.

Absorption:

Dist.:

Metabolism.:

Excretion, t½:

Toxicity/S.E.s:

Utility: Used in conjunction w/thioamides for preoperative preparation to diminish vascularity and swelling of thyroid gland ® reduced operative mortality. Treatment of thyrotoxicosis. Blocks synthesis and release of thyroid hormones. Rapid effect.

Special Features: No longer used very much.

Name: Methimazole (Tapazole)

Class: Antithyroid Drug (Thioamide)

Mechanism: Blocks thyroid synthesis.

Absorption: Oral ® 80-95% bioavailability.

Dist.: 0% protein binding. High placental transfer. 100% transfer into milk.

Metabolism.: Conjugated to gluconamide.

Excretion, t½: <10% style=""> 3-5 hr.

Toxicity/S.E.s: 7% freq. of untoward rxns. Most common = rash. 0.12% develop agranulocytosis. Occurs suddenly in first months of therapy, preceded by a sore throat and fever. Unusual bleeding and bruising may occur. C/i in nursing mothers, but can be used (w/great caution) in pregnancy-complicated hyperthyroidism (may cause neonatal goiter); PTU is safer.

Utility: Treat hyperthyroidism, but relapse after single course ³ 50%.

Special Features: 5-10 mg/8 hr (or higher).

Name: Propylthiouracil (PTU)

Class: Antithyroid Drug (Thioamide)

Mechanism: Blocks thyroid synthesis.

Absorption: Oral ® 80-95% bioavailability.

Dist.: 80% protein binding. Poor placental transfer. 10% transfer into milk.

Metabolism.: Conjugated to gluconamide.

Excretion, t½: 35% excreted in urine, mostly as gluconamide. 1-2 hr.

Toxicity/S.E.s: 3% freq. of untoward rxns. Most common = rash. 0.44% develop agranulocytosis. Occurs suddenly in first months of therapy, preceded by a sore throat and fever. Unusual bleeding and bruising may occur. C/i in nursing mothers, but can be used (w/great caution) in pregnancy-complicated hyperthyroidism (may cause neonatal goiter).

Utility: Treat hyperthyroidism, but relapse after single course ³ 50%.

Special Features: 75-100 mg/8 hr (or higher).

Name: Liothyronine sodium (Cytomel)

Class: Thyroid Hormone

Mechanism: Sodium salt of T₃. T₃/T₄ synergize w/GH effects, increase BMR, potentiate catecholamine effects on heart, promote lipolysis, and decrease serum cholesterol.

Absorption: Oral ® 95% absorption.

Dist.: Poor placental transfer ® okay for pregnant E. Little in milk (use cautiously).

Metabolism.: Hepatic conjug. w/glucuronic & sulfuric acids.

Excretion, t½: Bile; some lost in stool due to enterohepatic circ. £ 2 d.

Toxicity/S.E.s: Salicylates and dicumarol compete for albumin binding sites ® marked increase of free levels.

Utility: Preferred in treatment of myxedema coma. Treat hypothyroidism and goiter (not due to iodine deficiency or hyperthyroidism).

Special Features: 50-75 mg/d. 4x the potency of levothyroxine sodium, but same efficacy.

Name: Levothyroxine sodium (Synthroid, Levothroid, Levoxine)

Class: Thyroid Hormone

Mechanism: Sodium salt of T₄. T₃/T₄ synergize w/GH effects, increase BMR, potentiate catecholamine effects on heart, promote lipolysis, and decrease serum cholesterol.

Absorption: Incomplete oral absorption—30-40% recovered in stool.

Dist.: Poor placental transfer ® okay for pregnant E. Little in milk (use cautiously).

Metabolism.: Hepatic conjug. w/glucuronic & sulfuric acids. Peripheral deiodination to T₃.

Excretion, t½: Bile; some lost in stool due to enterohepatic circ. 6-7 d.

Toxicity/S.E.s: Salicylates and dicumarol compete for albumin binding sites ® marked increase of free levels.

Utility: Treat hypothyroidism and goiter (not due to iodine deficiency or hyperthyroidism).

Special Features: 200-300 mg/d. 1/4 the potency of liothyronine sodium, but same efficacy.