Chlorothiazide

Mechanism :

Chlorothiazide is a thiazide diuretic. The mechanism of action of Chlorothiazide is an interference with the renal tubular mechanism of electrolyte reabsorption. Thiazides increase excretion of sodium and chloride in approximately equivalent amounts. Natriuresis causes a secondary loss of potassium and bicarbonate.

Indication :

Hypertension
Nephrogenic diabetes insipidus
Congestive cardiac failure
Hyperinsulinemia

Contraindications :

Chlorothiazide is contraindicated in anuria. It is also contraindicated in patients who have previously demonstrated hypersensitivity to Chlorothiazide or other sulfonamide-derived drugs, severe renal and hepatic failure, Addison’s disease and hypercalcemia.

Dosing :

10-20 mg/kg/day PO single or two divided doses, Max: 375 mg/day.

Adverse Effect :

Nausea, vomiting, cramping, anorexia, dizziness, vertigo, paresthesia, headache, xanthopsia, leukopenia, agranulocytosis, thrombocytopenia, hemolytic anemia, aplastic anemia, pruritus, urticaria, necrotizing angiitis, orthostatic hypotension, muscle spasm, hyperglycemia, glycosuria, hyperuricemia, glomerulonephritis, transient blurred vision.

Interaction :

Alcohol, barbiturates, or narcotics: Potentiation of ortho-static hypotension.
Anticoagulants: Bendroflumethiazide may decrease their effects.
Amphotericin B, Corticosteroids, or Corticotropin: Intensify electrolyte imbalance, particularly hypokalemia.
Antigout medications: Bendroflumethiazide may raise the level of blood uric acid.
Antidiabetic drugs: elevate blood glucose levels, dosage adjustments of antidiabetic agents may be necessary.
Calcium Salts: Increased serum calcium levels due to decreased excretion.
Cardiac Glycosides: Enhanced possibility of digitalis toxicity.
Lithium Salts: May enhance lithium toxicity due to reduced renal clearance.
Nondepolarizing Muscle Agents: Effects of these agents may be potentiated; dosage adjustments may be required.
Nonsteroidal Anti-Inflammatory Agents: Can reduce the diuretic, natriuretic, and antihypertensive effect of loop, potassium-sparing or thiazide diuretics.
Pressor Amines: Decreased arterial responsiveness.
Probenecid or Sulfinpyrazone: Increased dosage of these agents may be necessary since bendroflumethiazide may have hyperuricemic effects.

Hepatic Dose :

No dosage adjustments are recommended. Diuretics should be used with caution in patients with hepatic disease since minor alterations of fluid and electrolyte balance may precipitate hepatic coma.