====== Acetazolamide (Diamox®) ======<WRAP right 340px><WRAP infobox>| | {{ :cardio:diuretics:acetazolamide_structure.svg |}} |^ Acetazolamide || Brand Names | Diamox® || Drug Class | [[cardio:diuretics:carbonic_anhydrase:start|Carbonic Anhydrase Inhibitor]] || Primary Indications | Glaucoma; Altitude sickness; Metabolic alkalosis; Idiopathic intracranial hypertension || Blood Pressure Effect | Mild ↓ BP || Mortality Benefit | No || Elimination | Renal || Black Box Warning | No || FDA Approval | 1954 |</WRAP></WRAP>===== Overview =====Acetazolamide is a carbonic anhydrase inhibitor that reduces proximal bicarbonate reabsorption, producing a mild diuresis and metabolic acidosis. It is used for glaucoma, altitude sickness, metabolic alkalosis, and to reduce CSF/aqueous production.<WRAP clear></WRAP>----===== Mechanism of Action =====**Primary Molecular Target**  * Carbonic anhydrase (proximal tubule)**Segment Effects**  * ↓ HCO3− reabsorption in proximal tubule  * ↑ NaHCO3 and water excretion  * Mild natriuresis**Net Physiologic Outcomes**  * Mild diuresis  * Metabolic acidosis  * ↓ Aqueous humor and CSF production----===== Indications =====  * Glaucoma (↓ aqueous humor)  * Altitude sickness prophylaxis/treatment  * Metabolic alkalosis  * Idiopathic intracranial hypertension  * Periodic paralysis (selected cases)----<WRAP blackbox>===== Black Box Warning =====No black box warning.</WRAP>----<WRAP contra>===== Contraindications =====Absolute:  * Sulfonamide allergy (severe)  * Severe hepatic disease (risk of encephalopathy)Relative / Caution:  * Hyponatremia  * Hypokalemia  * Renal impairment  * COPD (risk of acidosis)</WRAP>----<WRAP details>===== Dosing =====Typical dosing varies by indication:  * Glaucoma: 250–1000 mg/day divided  * Altitude sickness: 125–250 mg BID  * IIH: 500–1000 mg/day (titrate)Renal adjustment:  * Required in reduced eGFR</WRAP>----<WRAP details>===== Pharmacokinetics =====Absorption:  * OralBioavailability:  * ~90%Metabolism:  * MinimalHalf-life:  * ~10–15 hoursElimination:  * Renal (unchanged)</WRAP>----<WRAP details>===== Adverse Effects =====Common:  * Paresthesias  * Polyuria  * Metallic taste  * FatigueSerious:  * Metabolic acidosis  * Nephrolithiasis  * Hypokalemia  * Sulfa reactions</WRAP>----<WRAP details>===== Drug Interactions =====Increased risk:  * Other diuretics (electrolyte loss)  * Salicylates (toxicity risk)Avoid combination:  * High-dose aspirin in severe renal/hepatic disease</WRAP>----<WRAP monitoring>===== Monitoring =====Labs:  * Bicarbonate  * Electrolytes (K+, Na+)  * CreatinineVitals:  * Blood pressureClinical:  * Symptoms of acidosis  * Paresthesias</WRAP>----<WRAP pearls>===== Clinical Pearls =====  * Weak diuretic but powerful for glaucoma/altitude  * Causes a non–anion gap metabolic acidosis  * Can cause kidney stones (alkaline urine)</WRAP>----===== Comparison Within Class =====Compared to other [[cardio:diuretics:carbonic_anhydrase:start|carbonic anhydrase inhibitors]]:  * Shorter BP effect than thiazides/loops  * Unique use in altitude sickness/IIH  * Most commonly used CAI diuretic----===== Related =====  * [[cardio:diuretics:carbonic_anhydrase:start|Carbonic Anhydrase Inhibitors]]  * [[cardio:diuretics:start|Diuretics]]  * [[cardio:intro:start|Cardiovascular Pharmacology]]