Name: Triamterene (Dyrenium)
Class: Diuretic (Potassium Sparing Diuretic)
Mechanism: Inhib. Na+ channel in the apical membrane of the late distal tubule and collecting duct ® block of electrochemical gradient that drives K+ & H+ secretion ® diuresis & ¯ excretion of K+ & H+. Weak anti-HTN activity.
Absorption: Oral
Dist.:
Metabolism.:
Excretion, t½: 1° = kidney. 3 hr.
Toxicity/S.E.s: Hyperkalemia (most severe), n/v (most common), Metabolismolic acidosis. Hyponatremia may occur in old folks. Absolutely contraindicated with hyperkalemia. Adverse rxns w/lithium, ACE inhibitors. Rare renal failure w/NSAIDs.
Utility: Usu. given w/another diuretic (often thiazide or loop). Combination usu. ® normal K+ excretion. Used to prevent or correct hypokalemia, and to avoid K+ depletion in pts. on digitalis.
Special Features: Rel. weak diuretic.