Acetazolamide
Acetazolamide (Diamox)
Acetazolamide
(ah-set-ah- ZOE-la-myd)
Pregnancy Category: C Acetazolam Apo-Acetazolamide Dazamide Diamox Diamox Sequels Novo-Zolamide (Rx)
Acetazolamide sodium
Acetazolamide sodium (Diamox)
Acetazolamide sodium
(ah-set-ah- ZOE-la-myd) Diamox (Rx)

Classification: Anticonvulsant, carbonic anhydrase inhibitor

See Also: See also Anticonvulsants.

Action/Kinetics: Sulfonamide derivative possessing carbonic anhydrase inhibitor activity. As an anticonvulsant, beneficial effects may be due to inhibition of carbonic anhydrase in the CNS, which increases carbon dioxide tension resulting in a decrease in neuronal conduction. Systemic acidosis may also be involved. As a diuretic, the drug inhibits carbonic anhydrase in the kidney, which decreases formation of bicarbonate and hydrogen ions from carbon dioxide, thus reducing the availability of these ions for active transport. Use as a diuretic is limited because the drug promotes metabolic acidosis, which inhibits diuretic activity. This may be partially circumvented by giving acetazolamide on alternate days. Acetazolamide also reduces intraocular pressure.
Absorbed from the GI tract and widely distributed throughout the body, including the CNS. Excreted unchanged in the urine. Tablets: Onset, 60-90 min; peak: 1-4 hr; duration: 8-12 hr. Sustained-release capsules: Onset, 2 hr; peak: 3-6 hr; duration: 18-24 hr. Injection (IV): Onset, 2 min; peak: 15 min; duration: 4-5 hr. Eliminated mainly unchanged through the kidneys.

Uses: Adjunct in the treatment of edema due to congestive heart failure or drug-induced edema. Absence (petit mal) and unlocalized seizures. Open-angle, secondary, or acute-angle closure glaucoma when delay of surgery is desired to lower intraocular pressure. Prophylaxis or treatment of acute mountain sickness in climbers attempting a rapid ascent or in those who are susceptible to mountain sickness even with gradual ascent.

Contraindications: Low serum sodium and potassium levels. Renal and hepatic dysfunction. Hyperchloremic acidosis, adrenal insufficiency, suprarenal gland failure, hypersensitivity to thiazide diuretics, cirrhosis. Chronic use in presence of noncongestive angle-closure glaucoma.

Special Concerns: Use with caution in the presence of mild acidosis and advanced pulmonary disease and during lactation. Increasing the dose does not increase effectiveness and may increase the risk of drowsiness or paresthesia. Safety and efficacy have not been established in children.

Side Effects: GI: Anorexia, N&V;, melena, constipation, alteration in taste, diarrhea. GU: Hematuria, glycosuria, urinary frequency, renal colic, renal calculi, crystalluria, polyuria, phosphaturia, decreased or absent libido, impotence. CNS: Seizures weakness, malaise, fatigue, nervousness, drowsiness, depression, dizziness, disorientation, confusion, ataxia, tremor, headache, tinnitus, flaccid paralysis, lassitude, paresthesia of the extremities. Hematologic: Bone marrow depression thrombocytopenic purpura, thrombocytopenia, hemolytic anemia leukopenia, pancytopenia, agranulocytosis. Dermatologic: Pruritus, urticaria, skin rashes, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis photosensitivity. Other: Weight loss, fever, acidosis, electrolyte imbalance, transient myopia, hepatic insufficiency. NOTE: Side effects similar to those produced by sulfonamides may also occur.

Overdose Management: Symptoms: Drowsiness, anorexia, N&V;, dizziness, ataxia, tremor, paresthesias, tinnitus. Treatment: Emesis or gastric lavage. Hyperchloremic acidosis may respond to bicarbonate. Administration of potassium may also be necessary. Observe carefully and give supportive treatment.

Drug Interactions:
Also see Diuretics. Amphetamine / Amphetamine effect by renal tubular reabsorption Cyclosporine / Cyclosporine levels possible nephrotoxicity and neurotoxicity Diflunisal / Significant in intraocular pressure with side effects Ephedrine / Ephedrine effect R/T renal tubular reabsorption Lithium carbonate / Lithium effect by renal excretion Methotrexate / Methotrexate effect R/T renal excretion Primidone / Primidone effect R/T GI absorption Pseudoephedrine / Pseudoephedrine effect by renal tubular reabsorption Quinidine / Quinidine effect by renal tubular reabsorption Salicylates / Accumulation and toxicity of acetazolamide (including CNS depression and metabolic acidosis). Also, acidosis due to CNS penetration of salicylates

How Supplied: Acetazolamide: Capsule, Extended Release: 500 mg; Tablet: 125 mg, 250 mg. Acetazolamide sodium: Powder for injection: 500 mg

Dosage
?Extended-Release Capsules, Tablets, IV Epilepsy.
Adults/children: 8-30 mg/kg/day in divided doses. Optimum daily dosage: 375-1,000 mg (doses higher than 1,000 mg do not increase therapeutic effect).
Adjunct to other anticonvulsants.
Initial: 250 mg/day; dose can be increased up to 1,000 mg/day in divided doses if necessary.
Glaucoma, simple open-angle.
Adults: 250-1,000 mg/day in divided doses. Doses greater than 1 g/day do not increase the effect.
Glaucoma, closed-angle prior to surgery or secondary.
Adults, short-term therapy: 250 mg q 4 hr or 250 mg b.i.d. Adults, acute therapy: 500 mg followed by 125-250 mg q 4 hr using tablets. For extended-release capsules, give 500 mg b.i.d. in the morning and evening. IV therapy may be used for rapid decrease in intraocular pressure. Pediatric: 5-10 mg/kg/dose IM or IV q 6 hr or 10-15 mg/kg/day in divided doses q 6-8 hr using tablets.
Acute mountain sickness.
Adults: 250 mg b.i.d.-q.i.d. (500 mg 1-2 times/day of extended-release capsules). During rapid ascent, 1 g/day is recommended.
Diuresis in CHF.
Adults, initial: 250-375 mg (5 mg/kg) once daily in the morning. If the client stops losing edema fluid after an initial response, the dose should not be increased; rather, medication should be skipped for a day to allow the kidney to recover. The best diuretic effect occurs when the drug is given on alternate days or for 2 days alternative with a day of rest.
Drug-induced edema.
Adults: 250-375 mg once daily for 1 or 2 days. The drug is most effective if given every other day or for 2 days followed by a day of rest. Children: 5 mg/kg/dose PO or IV once daily in the morning.