A diuretic drug of the thiazide class that acts by inhibiting the kidney’s ability to retain water.

Most commonly utilized thiazide diuretic.

About 10 million people in the US use this agent.

Routes include oral capsules, tablets, and oral solution.

Variably absorbed from GI tract with a 70% bioavailability.

Has a half-life of approximately 12 hours.

The antihypertensive action of HCTZ is only 8 hours in duration, but it is administered once a day.

Does not undergo significant metabolism with greater than 95% excreted unchanged in urine.

Half-life of 5.6–14.8 hours.

Primarily excreted unchanged in urine.

Belongs to thiazide class of diuretics, and it reduces blood volume by acting on the kidneys to reduce sodium(Na) reabsorption in the distal convoluted tubule.

Reduces the volume of the blood, decreasing blood return to the heart and thus cardiac output and, by other mechanisms, is believed to lower peripheral vascular resistance.

The major site of action in the nephron appears on an electroneutral Na +-Cl − co-transporter by competing for the chloride site on the transporter.

By impairing Na transport in the distal convoluted tubule, induces a natriuresis and concomitant water loss.

Increase the reabsorption of calcium in this segment in a manner unrelated to sodium transport.

Believed to lower peripheral vascular resistance as well.

Frequently used for the treatment of hypertension, congestive heart failure, symptomatic edema, diabetes insipidus, renal tubular acidosis, and the prevention of kidney stones.

Sometimes used for treatment of hypoparathyroidism, hypercalciuria, and Ménière’s disease, and diabetes insipidus.

Use in diabetes insipidus is mediated by a hypovolemia-induced increase in proximal sodium and water reabsorption, thereby diminishing water delivery to the ADH-sensitive sites in the collecting tubules and increasing the urine output.

Recent data suggest that 12.5 mg HCTZ may not have any impact on elevated blood pressures.

Can increase the risk of lip cancer.

Long term use associated with a 7 fold increase in squamous cell skin cancer due to increased sun UV sensitivity.

Can be used in the treatment of osteoporosis, as thiazides decrease mineral bone loss by promoting calcium retention in the kidney, and by stimulating osteoblast differentiation and bone mineral formation.

Frequently given together with other antihypertensive agents in fixed combination preparations.

Side effects include: hypokalemia, hypomagnesemia, hyponatremia, hyperuricemia, hyperglycemia, hyperlipidemia, hypercalcemia, headache, nausea/vomiting, photosensitivity, weight gain, pancreatitis and gout.

has a short duration of action of 6 to 12 hours compared with chlorthalidone at 48-72 hours or indapamide, the latter  being 10 times as potent as the other 2 with about a 24/2 hour life.

Chlorthalidone is more effective in lowering systolic blood pressure than hydrochlorothiazide.

Alternative agents include indapamide and chlorthalidone.

Among patients with recurrent kidney stones, the incidence of recurrence is not different substantially among patients receiving hydrochlorothiazide once daily, at doses of 12.5, 25, or 50 mg or placebo once daily (Dhayat NA).

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