Drug Guide
Acetazolamide
Classification
Therapeutic: Diuretic, Antiglaucoma, Altitude Sickness Prophylactic
Pharmacological: Carbonic Anhydrase Inhibitor
FDA Approved Indications
- Glaucoma (elevated intraocular pressure)
- Edema associated with congestive heart failure or drug therapy that includes edema
- Altitude sickness prevention and treatment
- Epilepsy (adjunctive)
Mechanism of Action
Inhibits the enzyme carbonic anhydrase, leading to decreased hydrogen ion secretion at proximal tubules in kidneys, resulting in increased excretion of sodium, bicarbonate, water, and potassium, thereby reducing aqueous humor formation and intraocular pressure.
Dosage and Administration
Adult: Typically 250 mg to 750 mg daily in divided doses; dosages vary based on condition.
Pediatric: Dosed based on weight or age, commonly 8-13 mg/kg/day divided into multiple doses.
Geriatric: Start at lower doses due to increased sensitivity and renal function decline.
Renal Impairment: Reduce dosage as renal function declines—monitor renal function closely.
Hepatic Impairment: Use with caution; no specific dose adjustment required but monitor closely.
Pharmacokinetics
Absorption: Rapidly absorbed from gastrointestinal tract.
Distribution: Widely distributed; crosses the blood-brain barrier and placenta.
Metabolism: Poorly metabolized, mostly excreted unchanged.
Excretion: Primarily excreted unchanged in urine.
Half Life: approximately 10-15 hours, varies with renal function.
Contraindications
- Hypersensitivity to sulfonamides or of acetazolamide.
- Severe hepatic or respiratory failure.
- Caution in history of kidney stones, electrolyte disturbances, or metabolic acidosis.
Precautions
- Monitor electrolytes, renal function, and acid-base balance during therapy.
- Use with caution in pregnant women—category B, generally avoided in early pregnancy.
- Lactation: Crosses into breast milk; weigh risks and benefits.
Adverse Reactions - Common
- Paresthesias (Common)
- Dizziness (Common)
- Altered taste (Common)
- Polyuria (Common)
- Gastrointestinal upset (Common)
Adverse Reactions - Serious
- Electrolyte disturbances (hypokalemia, hyponatremia) (Serious)
- Metabolic acidosis (Serious)
- Nephrolithiasis (kidney stones) (Serious)
- Blood dyscrasias (e.g., aplastic anemia, leukopenia) (Serious)
- Severe allergic reactions (rash, Stevens-Johnson syndrome) (Serious)
Drug-Drug Interactions
- Corticosteroids (potentiates hypokalemia)
- Other diuretics
- Sodium bicarbonate or other alkali agents (can enhance metabolic acidosis)
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor baseline and periodic renal function, electrolytes, acid-base status, and visual status.
Diagnoses:
- Risk for electrolyte imbalance
- Risk for metabolic acidosis
- Risk for dehydration
Implementation: Administer with food if gastrointestinal upset occurs. Encourage adequate hydration.
Evaluation: Assess intraocular pressure, electrolyte levels, and patient response to therapy.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report signs of electrolyte imbalance (muscle weakness, irregular heartbeat).
- Maintain hydration and adequate electrolyte intake.
- Avoid activities requiring alertness if dizziness occurs.
Special Considerations
Black Box Warnings:
- Not approved for treatment of edema in patients with cirrhosis or hepatic coma.
- Potential for blood dyscrasias; monitor blood counts during prolonged therapy.
Genetic Factors: Variations in drug metabolism and response may occur.
Lab Test Interference: Can cause false increase in blood glucose and serum bicarbonate levels.
Overdose Management
Signs/Symptoms: Profound metabolic acidosis, dehydration, electrolyte abnormalities, CNS disturbances.
Treatment: Discontinue drug; provide supportive care, correct acid-base and electrolyte disturbances, and maintain hydration.
Storage and Handling
Storage: Store at room temperature, away from light and moisture.
Stability: Stable when stored properly; check expiration date.