Microzide

Microzide is the brand name for hydrochlorothiazide (HCTZ), a thiazide diuretic used primarily to treat high blood pressure and fluid retention. It may also be prescribed to prevent calcium-containing kidney stones and to manage edema associated with congestive heart failure, cirrhosis, or chronic kidney disease.

Mechanism of action and effects

Hydrochlorothiazide works by inhibiting the sodium-chloride cotransporter in the distal convoluted tubule of the kidney. This decreases reabsorption of sodium and water, producing diuresis. It also reduces calcium excretion in the urine, which can help prevent certain types of kidney stones. The effect is mild to moderate and is typically most useful when combined with other antihypertensive or diuretic strategies.

Formulations and dosing

Microzide tablets are commonly available in 12.5 mg and 25 mg strengths. The usual starting dose for hypertension is 12.5–25 mg once daily, which can be increased to up to 50 mg per day in divided doses or as a single daily dose, depending on response and tolerance. Dosing for edema may be similarly adjusted. Treatment should be individualized and guided by blood pressure, electrolyte status, and kidney function.

Pharmacokinetics

Orally administered hydrochlorothiazide is absorbed with onset within about 2 hours and a duration of action generally around 6–12 hours. It is largely excreted unchanged in the urine, with a half-life typically in the range of about 5–15 hours.

Adverse effects and considerations

Common concerns include dehydration, low blood pressure, and electrolyte disturbances such as hyponatremia or hypokalemia. Hyperglycemia can occur in some patients, and photosensitivity may be increased. Caution is advised in gout, preexisting electrolyte imbalances, kidney disease, or when used with other drugs that affect electrolytes or kidney function. Monitoring of blood pressure, electrolytes, uric acid, and glucose is recommended during therapy.