| Item |
Information |
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Drug Groups
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approved |
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Description
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A thiazide diuretic often considered the prototypical member of this class. It reduces the reabsorption of electrolytes from the renal tubules. This results in increased excretion of water and electrolytes, including sodium, potassium, chloride, and magnesium. It has been used in the treatment of several disorders including edema, hypertension, diabetes insipidus, and hypoparathyroidism. [PubChem] |
| Indication |
For the treatment of high blood pressure and management of edema. |
| Pharmacology |
Thiazides such as hydrochlorothiazide promote water loss from the body (diuretics). They inhibit Na+/Cl- reabsorption from the distal convoluted tubules in the kidneys. Thiazides also cause loss of potassium and an increase in serum uric acid. Thiazides are often used to treat hypertension, but their hypotensive effects are not necessarily due to their diuretic activity. Thiazides have been shown to prevent hypertension-related morbidity and mortality although the mechanism is not fully understood. Thiazides cause vasodilation by activating calcium-activated potassium channels (large conductance) in vascular smooth muscles and inhibiting various carbonic anhydrases in vascular tissue. |
| Toxicity |
The most common signs and symptoms observed are those caused by electrolyte depletion (hypokalemia, hypochloremia, hyponatremia) and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia may accentuate cardiac arrhythmias. The oral LD50 of hydrochlorothiazide is greater than 10 g/kg in the mouse and rat. |
| Affected Organisms |
| • |
Humans and other mammals |
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| Biotransformation |
Hydrochlorothiazide is not metabolized. |
| Absorption |
50-60% |
| Half Life |
5.6 and 14.8 hours |
| Protein Binding |
67.9% |
| Elimination |
Hydrochlorothiazide is not metabolized but is eliminated rapidly by the kidney. Hydrochlorothiazide crosses the placental but not the blood-brain barrier and is excreted in breast milk. |
| External Links |
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