Hydrochlorothiazide

Hydrochlorothiazide

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Systematic (IUPAC) name
6-chloro-1,1-dioxo-3,4-dihydro-2H-1,2,4-benzothiadiazine-7-sulfonamide
Clinical data
Pregnancy category	B (D if used to treat pregnancy-induced hypertension)
Routes of administration	Oral (capsules, tablets, oral solution)
Legal status
Legal status	℞ (Prescription only)
Pharmacokinetic data
Bioavailability	Variably absorbed from GI tract
Metabolism	does not undergo significant metabolism (>95% excreted unchanged in urine)
Biological half-life	5.6-14.8 h
Excretion	Primarily excreted unchanged in urine
Identifiers
CAS Number	58-93-5
ATC code	C03AA03 (WHO)
PubChem	CID 3639
ChemSpider	3513
Chemical data
Formula	C7H8ClN3O4S2
Molar mass	297.74[[]]
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Hydrochlorothiazide, abbreviated HCTZ, HCT, or HZT, is a first line diuretic drug of the thiazide class that acts by inhibiting the kidneys' ability to retain water. This 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. Hydrochlorothiazide is sold both as a generic drug and under a large number of brand names, including Apo-Hydro, Aquazide H, Dichlotride, Hydrodiuril, HydroSaluric, Microzide, Esidrex, and Oretic.

Hydrochlorothiazide is also used in combination with many popular drugs used to treat hypertension such as Diovan HCT, Zestoretic, Benicar HCT, Atacand HCT, and Lotensin HCT, Temax-H and others.

Mechanism of action

Hydrochlorothiazide belongs to the thiazide class of diuretics, acting on the kidneys to reduce sodium (Na) reabsorption in the distal convoluted tubule. 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, hydrochlorothiazide induces a natriuresis and concomitant water loss. Thiazides increase the reabsorption of calcium in this segment in a manner unrelated to sodium transport. .

Indications

HCTZ is often used in the treatment of hypertension, congestive heart failure, symptomatic edema and the prevention of kidney stones. It is effective for nephrogenic diabetes insipidus and is also sometimes used for hypercalciuria, Dent's disease and Ménière's disease. For diabetes insipidus, the effect of thiazide diuretics is presumably 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 reducing the urine output.

Hypokalemia, an occasional side effect, can be usually prevented by potassium supplements or by combining hydrochlorothiazide with a potassium-sparing diuretic.

Thiazides are also used in the treatment of osteoporosis. Thiazides decrease mineral bone loss by promoting calcium retention in the kidney, and by directly stimulating osteoblast differentiation and bone mineral formation.

Side effects

• Hypokalemia
• Hypomagnesemia
• Hyperuricemia and gout
• High blood sugar
• Hyperlipidemia
• Hypercalcemia
• Headache
• Nausea/vomiting
• Photosensitivity
• Weight Gain

Please Note - you may experience an allergic reaction to this medication if you are allergic to sulfa drugs.

See also

• Benicar HCT
• Diovan HCT

External links

• NIH medlineplus druginfo
• U.S. National Library of Medicine: Drug Information Portal - Hydrochlorothiazide

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