Triamterene causes its potassium-sparing effects mainly by which of the following?
|A||Blocking distal tubular sodium channels and, ultimately, Na+ - K+ exchange|
|B||Enhancing the affinity of aldosterone for its renal tubular receptors|
|C||Hastening metabolic inactivation of aldosterone|
|D||Inhibiting a proximal tubular Na, K-ATPase|
a. Triamterene and amiloride block distal tubular Na+ channels that is for Na+ reabsorption in exchange for K which is lost into the urine.
b. The actions of these drugs have nothing to do with effects on aldosterone metabolism or aldosterone receptors (the latter being blocked by spironolactone,). None of these agents should be administered to patients who are hyperkalemic, and to avoid causing hyperkalemia, they should not be administered with oral potassium supplements or other drugs that increase circulating potassium levels.
c. These drugs are important in management of hypertension and congestive cardiac failure. Hyperkalemia is an important side effect of these drugs.