True about triamterene is A/E –
**Core Concept**
Triamterene is a potassium-sparing diuretic that acts as a weak inhibitor of the sodium-potassium-chloride cotransporter (NKCC2) in the distal convoluted tubule of the kidneys. This action reduces sodium reabsorption, leading to increased sodium and water excretion, while sparing potassium.
**Why the Correct Answer is Right**
Triamterene works by blocking the NKCC2 cotransporter, which is responsible for reabsorbing sodium, potassium, and chloride ions in the distal convoluted tubule. By inhibiting this transporter, triamterene decreases sodium reabsorption, leading to increased sodium and water excretion. This action also reduces potassium secretion, resulting in potassium sparing. The potassium-sparing effect of triamterene is particularly useful in patients with hypertension and heart failure.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because triamterene's primary mechanism of action is inhibition of the NKCC2 cotransporter, not the Na+/K+-ATPase pump.
**Option B:** This option is incorrect because while triamterene does have a mild diuretic effect, its primary action is potassium sparing, not potassium excretion.
**Option C:** This option is incorrect because triamterene is not a direct renin inhibitor, but rather a potassium-sparing diuretic that acts on the distal convoluted tubule.
**Clinical Pearl / High-Yield Fact**
Triamterene is often used in combination with other diuretics, such as hydrochlorothiazide, to enhance its diuretic and antihypertensive effects while minimizing potassium loss.
**Correct Answer: A. All of the above.**