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acetazolamide (Diamox)

Tradename: Diamox. Indications: 1) management of edema secondary to chronic heart failure (CHF) 2) glaucoma a) adjunct for therapy of open angle glaucoma b) closed angle glaucoma [7] c) secondary glaucoma [7] 3) idiopathic intracranial hypertension (pseudotumor cerebri) [5] 4) adjunct to other anticonvulsants in prophylactic management of epilepsy, especially absence (petit mal) seizures 5) high altitude sickness 6) motion sickness 7) treatment of metabolic alkalosis in patients with hypervolemia & sodium overload (urinary alkalinization) [5,6,7] 8) hydrocephalus [7] 9) intracranial hemorrhage 10) familial periodic paralysis 11) anoxia [7] Dosage: 1) adults a) glaucoma - 250 mg PO QD-QID - 500 mg sustained-release capsule BID - 250-500 mg IV/IM; may repeat in 2-4 hours b) edema: 250-375 mg PO/IV/IM QD c) epilepsy: 8-30 mg/kg/day PO divided QD-QID d) altitude sickness: - prophylaxis: - 125-250 mg PO every 8-12 hours - begin 1 day before ascent - continue for 2 days after reaxhing destination e) 250 mg IV/PO QD/BID/TID/QID 2) children a) glaucoma: - oral: 8-30 mg/kg/day divided every 6-8 hours - IM/IV: 20-40 mg/kg/day divided every 6 hours b) edema: 5 mg/kg or 150 mg/m2 PO/IM/IV QD or QOD c) epilepsy: - 8-30 mg/kg/day PO divided BID-QID - max:P 1 g/day Tabs: 125, 250, 500 mg. Adverse effects: 1) common (> 10%) - malaise - anorexia - diarrhea - metallic taste - polyuria - muscle weakness 2) uncommon (< 1%) - fever, fatigue, depression, drowsiness, rash, hyperchloremic metabolic acidosis, hypokalemia, GI irritation, dry mouth, melena, dysuria, hyperglycemia, paresthesia, myopia 3) other - kidney stones (renal calculi), uncommon < 1% - diminished uric acid secretion - crystalluria - dysuria - seizures - bone marrow suppression (rare) - aplastic anemia - thrombocytopenia - neutropenia - lymphopenia - hypertrichosis - nausea/vomiting - sedation - headache - sulfa hypersensitivity reactions - hemolytic anemia Drug interactions: 1) increased lithium excretion 2) enhanced activity of other diuretics 3) via alkalinization of the urine - diminished excretion of amphetamines, procainamide, quinidine, tricyclic antidepressants Laboratory: - acetazolamide in blood - acetazolamide in serum/plasma - acetazolamide in urine Mechanism of action: 1) reversible inhibitor of carbonic anhydrase 2) diuretic 3) alkalinization of urine 4) increases urine volume (promptly after administration) 5) normally acidic urine pH becomes alkaline. 6) increases urinary excretion of bicarbonate & Na+ - urinary concentration of bicarbonate increases; matched by Na+ & substantial amounts of K+ 7) urinary concentration of Cl- falls 8) the increased alkalinity of the urine is necessarily accompanied by a decrease in the excretion of a) titratable acid b) ammonia 9) indirect inhibition of H+ secretion by the renal tubules through inhibition of carbonic anhydrase 10) for glaucoma, acetazolamide works by decreasing formation of aqueous humor 11) lowers pulmonary vascular resistance [4]

Interactions

drug interactions drug adverse effects (more general classes) monitor with carbonic anhydrase inhibitors

General

carbonic anhydrase inhibitor sulfonamide

Properties

INHIBITS: carbonic anhydrase (dehydratase) MISC-INFO: elimination route KIDNEY pregnancy-category C safety in lactation ?

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 8th ed. Gilman et al, eds. Permagon Press/McGraw Hill pg 716
  2. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  3. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  4. Teppema LJ, Balanos GM, Steinback CD et al Effects of acetazolamide on ventilatory, cerebrovascular, and pulmonary vascular responses to hypoxia. Am J Respir Crit Care Med. 2007 Feb 1;175(3):277-81 PMID: 17095745
  5. Medical Knowledge Self Assessment Program (MKSAP) 14, 15, 16, 17. American College of Physicians, Philadelphia 2006, 2009, 2012, 2015
  6. Galla JH. Metabolic alkalosis. J Am Soc Nephrol. 2000 Feb;11(2):369-75. PMID: 10665945
  7. Deprecated Reference