Acetazolamide
Indications
Acetazolamide is used for:
Glaucoma, Epilepsy, Idiopathic intracranial hypertension, Altitude sickness
Adult Dose
Adult: PO Diuresis 250-375 mg/day.
Glaucoma; Epilepsy 250-1,000 mg/day.
Prophylaxis of high altitude sickness 500-1,000 mg/day.
Epilepsy
>12 years
Tablet: 8-30 mg/kg/day PO qDay or divided q6-12 hr; not to exceed 30 mg/kg/day or 1 g/day
Acute Altitude Sickness >12 years
Immediate release: 500-1000 mg/day PO divided q8-12hr
Hepatic impairment: Contraindicated in marked hepatic impairment.
Child Dose
<12 years: Safety and efficacy is not established
Renal Dose
Renal impairment: Contraindicated in marked renal impairment.
Administration
Should be taken with food.
Contra Indications
Hypersensitivity to sulphonamides; sodium or potassium depletion, hepatic insufficiency; hepatic cirrhosis; hyperchloraemic acidosis; severe renal impairment; severe pulmonary obstruction; chronic noncongestive angle-closure glaucoma; adrenocortical insufficiency. Pregnancy, lactation.
Precautions
Potassium supplements may be required. Impaired hepatic or renal function; diabetes. Monitor plasma electrolytes and blood count regularly. IM route is not recommended. Caution when driving or operating machinery. Elderly.
Lactation: Enters breast milk; not recommended
Pregnancy-Lactation
Pregnancy category: C
Lactation: Enters breast milk; not recommended
Interactions
Concomitant use w/ high-dose aspirin may cause anorexia, tachypnoea, lethargy, metabolic acidosis, coma and death. May increase serum levels of phenytoin, resulting to increased risk of osteomalacia. May decrease serum concentrations of primidone. Additive effects w/ other carbonic anhydrase inhibitors. May increase the effects of folic acid antagonists. May decrease urinary excretion of amphetamine and quinidine. May prevent the urinary antiseptic effect of methenamine. May increase lithium excretion. Increased risk of renal calculus formation w/ Na bicarbonate. May increase ciclosporin levels.
Side Effects
Side effects of Acetazolamide :
Drowsiness, paraesthesia, ataxia, dizziness, thirst, anorexia, headache; confusion, malaise, depression; GI distress, metabolic acidosis, polyuria, hyperuricaemia, renal calculi, nephrotoxicity, hepatic dysfunction.
Potentially Fatal: Rarely, skin reactions or blood dyscrasias.
Mode of Action
Acetazolamide specifically inhibits the enzyme carbonic anhydrase which catalyses the reversible reaction involving the hydration of CO2 and dehydration of carbonic acid. It increases the excretion of HCO3 ions and as well as Na and K leading to alkaline diuresis. Carbonic anhydrase is also inhibited in the CNS to retard abnormal and excessive discharge from neurons.