Comprehensive Guide to Acetazolamide: Uses, Dosage, Side Effects, and More

What is Acetazolamide?

Overview of Acetazolamide

Generic Name: Acetazolamide

Brand Name: Diamox, Diamox Sequels, generics

Drug Group: Carbonic anhydrase inhibitor; diuretic; anticonvulsant

The drug is used to

• Treat open-angle and secondary glaucoma, and lower intraocular pressure pre-surgery.
• Prevent and treat acute mountain sickness (altitude sickness).
• Manage epilepsy, particularly absence seizures, as adjunctive therapy.
• Treat edema associated with congestive heart failure or drug-induced fluid retention.
• Off-label uses include idiopathic intracranial hypertension and periodic paralysis under specialist guidance.

Key Characteristics

Form: Oral tablets (125 mg, 250 mg); sustained-release capsules (500 mg); IV injection (500 mg vial).

Mechanism: Inhibits carbonic anhydrase, reducing bicarbonate production, leading to diuresis, decreased intraocular pressure, and anticonvulsant effects.

Approval: FDA-approved (1953 for Diamox) and EMA-approved for glaucoma, epilepsy, and altitude sickness.

Indications and Uses of Acetazolamide

Acetazolamide is indicated for

Glaucoma: Reduces intraocular pressure in open-angle, secondary, or acute angle-closure glaucoma (pre-surgery).

Acute Mountain Sickness: Prevents and treats symptoms like headache, nausea, and fatigue at high altitudes.

Epilepsy: Adjunctive therapy for absence seizures (petit mal) and other seizure types in adults and children.

Edema: Promotes diuresis in fluid retention due to heart failure or medications.

Off-Label Uses: Treats idiopathic intracranial hypertension (pseudotumor cerebri), periodic paralysis, or hydrocephalus under specialist supervision.

Dosage of Acetazolamide

Dosage for Adults

Glaucoma:

• Open-Angle: 250 mg to 1 g/day orally, in 2–4 divided doses (tablets or sustained-release capsules).
• Acute Angle-Closure (Pre-Surgery): 250 mg every 4 hours or 500 mg twice daily.

Acute Mountain Sickness:

• Prevention: 125–250 mg orally twice daily, starting 1–2 days before ascent and continuing for 2 days at altitude.
• Treatment: 250 mg orally 2–4 times daily.

Epilepsy: 8–30 mg/kg/day orally, in 1–4 divided doses (typical range: 375–1,000 mg/day).

Edema: 250–375 mg orally or IV once daily for 1–2 days, followed by drug-free days (e.g., alternate-day dosing).

Idiopathic Intracranial Hypertension (Off-Label): 1–4 g/day orally, in divided doses, adjusted based on response.

Dosage for Children

Epilepsy: 8–30 mg/kg/day orally, divided into 2–4 doses (maximum 1 g/day).

Glaucoma or Edema: Not routinely used; consult a pediatric specialist for weight-based dosing.

Altitude Sickness: Limited data; typically 2.5 mg/kg every 12 hours for prevention.

Dosage for Pregnant Women

Pregnancy Category C: Avoid unless benefits outweigh risks, as animal studies suggest potential fetal harm. Consult a specialist.

Dosage Adjustments

Renal Impairment:

• CrCl 10–50 mL/min: Reduce dose by 50%.
• CrCl <10 mL/min: Avoid due to risk of metabolic acidosis.

Hepatic Impairment: Use cautiously; monitor for hepatic encephalopathy in cirrhosis.

Elderly: Start with lower doses due to risk of renal impairment or electrolyte imbalances.

Additional Considerations

• Take oral doses with food to reduce gastrointestinal upset.
• Ensure adequate hydration to prevent kidney stones.
• IV form is reserved for acute settings (e.g., glaucoma or edema).

5. How to Use Acetazolamide

Administration:

• Oral: Take tablets or capsules with food or water to minimize stomach upset. Swallow whole; do not crush sustained-release capsules.
• IV: Administered by healthcare professionals over 1–2 minutes in acute settings.

Timing: Follow prescribed schedule (e.g., twice daily for altitude sickness, divided doses for glaucoma). Consistency aids efficacy.

Missed Dose: Take as soon as remembered unless it’s nearly time for the next dose; do not double doses. Consult your doctor if multiple doses are missed.

Additional Tips:

• For altitude sickness, start 1–2 days before ascent and continue at altitude.
• Report symptoms like tingling, fatigue, or confusion, which may indicate side effects.
• Avoid alcohol, as it may worsen side effects like drowsiness.

6. Contraindications for Acetazolamide

The drug is contraindicated in

Patients with hypersensitivity to Acetazolamide, sulfonamides, or formulation components.

Those with severe renal impairment (CrCl <10 mL/min).

Patients with severe liver disease or cirrhosis (risk of hepatic encephalopathy).

Those with low sodium or potassium levels (hyponatremia, hypokalemia).

Patients with adrenal insufficiency or hyperchloremic acidosis.

7. Warnings & Precautions for Acetazolamide

General Warnings

Metabolic Acidosis: Risk of hyperchloremic metabolic acidosis, especially in renal impairment; monitor serum bicarbonate and electrolytes.

Kidney Stones: Increased risk of calcium phosphate stones; ensure adequate hydration.

Sulfonamide Hypersensitivity: Cross-reactivity possible in patients allergic to sulfonamides; monitor for rash or anaphylaxis.

Bone Marrow Suppression: Rare risk of agranulocytosis, thrombocytopenia, or aplastic anemia; monitor complete blood count (CBC).

Neurologic Effects: May cause drowsiness or confusion, particularly in elderly patients.

Use in Specific Populations

Pregnancy: Category C; avoid unless essential due to potential teratogenicity. Use contraception during therapy.

Breastfeeding: Excreted in breast milk; avoid breastfeeding due to risk to infant.

Elderly: Increased risk of metabolic acidosis and renal impairment; use lower doses.

Children: Safe for epilepsy and other indications with weight-based dosing; monitor closely.

Renal Impairment: Avoid in severe cases; adjust doses in moderate impairment.

Additional Precautions

• Inform your doctor about kidney, liver, or sulfonamide allergy history.
• Avoid activities requiring alertness (e.g., driving) if drowsy or dizzy.

Overdose and Management of Acetazolamide

Overdose Symptoms

• Severe drowsiness or confusion.
• Metabolic acidosis (e.g., rapid breathing, fatigue).
• Electrolyte imbalances (e.g., low potassium, low sodium).
• Nausea, vomiting, or tremor.

Immediate Actions

Contact Healthcare Provider: Seek medical advice immediately.

Supportive Care: Administer fluids and electrolytes to correct acidosis or imbalances.

Monitor: Check electrolytes, renal function, and acid-base status.

Additional Notes

• Overdose risk is low with proper dosing; store securely to prevent misuse.
• Report persistent symptoms promptly.

9. Side Effects of Acetazolamide

Common Side Effects

• Paresthesia (tingling in hands/feet; 20–40%)
• Fatigue or drowsiness (10–20%)
• Nausea or vomiting (10–15%)
• Loss of appetite (5–10%)
• Metallic taste or altered taste (5–10%)

These effects are often transient but may persist in some patients.

Serious Side Effects

Seek immediate medical attention for:

Metabolic Acidosis: Rapid breathing, confusion, or extreme fatigue.

Allergic Reactions: Rash, hives, or difficulty breathing (sulfonamide-related).

Hematologic: Unusual bruising, bleeding, or severe fatigue.

Renal: Kidney stones (painful urination, blood in urine).

Neurologic: Seizures or severe confusion.

Additional Notes

• Regular monitoring of electrolytes, CBC, and renal function is essential.
• Report any rash or unusual symptoms immediately due to sulfonamide risk.

10. Drug Interactions with Acetazolamide

The medication may interact with

Salicylates (e.g., Aspirin): Increase risk of toxicity (e.g., metabolic acidosis); avoid high-dose aspirin.

Other Diuretics (e.g., Furosemide): Enhance diuresis, risking dehydration or electrolyte imbalances.

Anticonvulsants (e.g., Phenytoin, Carbamazepine): May increase osteomalacia risk; monitor bone health.

Lithium: Reduces lithium levels; monitor lithium concentrations.

Cyclosporine: Increases cyclosporine levels; monitor for toxicity.

Patient Education or Lifestyle

Medication Adherence: Take Acetazolamide as prescribed to maintain efficacy. Refill prescriptions early to avoid interruptions.

Hydration: Drink 2–3 L of water daily to prevent kidney stones, especially for long-term use.

Diet: Avoid high-sodium or high-potassium foods if electrolyte imbalances occur; consult a dietitian for glaucoma or epilepsy management.

Altitude Sickness: Plan high-altitude travel carefully; start the drug 1–2 days before ascent.

Monitoring: Attend regular appointments for electrolyte, renal, and CBC monitoring.

Allergy Awareness: Report any rash or breathing difficulties immediately due to sulfonamide risk.

Pharmacokinetics of Acetazolamide

Absorption: Well-absorbed orally (~100%); peak plasma concentration at 2–4 hours (tablets) or 8–12 hours (sustained-release).

Distribution: Widely distributed, including into erythrocytes and kidneys; crosses blood-brain barrier.

Metabolism: Minimal hepatic metabolism; primarily excreted unchanged.

Excretion: Renal (70–100% unchanged); reduced in renal impairment.

Half-Life: 10–15 hours (tablets); 15–18 hours (sustained-release).

Pharmacodynamics of Acetazolamide

The drug exerts its effects by:

• Inhibiting carbonic anhydrase, reducing bicarbonate production in kidneys, eyes, and brain.
• Decreasing intraocular pressure by reducing aqueous humor formation in glaucoma.
• Promoting diuresis and correcting alkalosis in edema.
• Stabilizing neuronal activity in epilepsy via pH modulation.
• Preventing altitude sickness by inducing mild acidosis, stimulating ventilation.

Storage of Acetazolamide

Temperature: Store at room temperature (20–25°C or 68–77°F); avoid moisture and heat.

Protection: Keep in original container to protect from light.

Safety: Store out of reach of children to prevent accidental ingestion.

Disposal: Follow local regulations or consult a pharmacist for safe disposal of unused or expired medication.

Frequently Asked Questions (FAQs)

Q: What does Acetazolamide treat?
A: The drug treats glaucoma, altitude sickness, epilepsy, and edema.

Q: Can Acetazolamide prevent altitude sickness?
A: Yes, start 1–2 days before ascent to prevent symptoms like headache or nausea.

Q: Is Acetazolamide safe for sulfonamide allergies?
A: No, avoid in sulfonamide allergies due to risk of cross-reactivity.

Q: How long does Acetazolamide take to work?
A: Effects begin within hours for glaucoma or altitude sickness; epilepsy control may take days.

Q: Can Acetazolamide cause kidney stones?
A: Yes, stay hydrated to reduce risk; report painful urination immediately.

Regulatory Information for Acetazolamide

The medication is approved by

U.S. Food and Drug Administration (FDA): Approved in 1953 (Diamox) for glaucoma, epilepsy, edema, and altitude sickness.

European Medicines Agency (EMA): Approved for similar indications.

Other Agencies: Approved globally for equivalent uses; consult local guidelines.

References

1. U.S. Food and Drug Administration (FDA). (2023). Diamox (Acetazolamide) Prescribing Information.
   • Official FDA documentation detailing the drug’s approved uses, dosage, and safety.
2. European Medicines Agency (EMA). (2023). Acetazolamide Summary of Product Characteristics.
   • EMA’s comprehensive information on the medication’s indications and precautions in Europe.
3. National Institutes of Health (NIH). (2023). Acetazolamide: MedlinePlus Drug Information.
   • NIH resource providing detailed information on the drug’s uses, side effects, and precautions.
4. World Health Organization (WHO). (2023). WHO Model List of Essential Medicines: Acetazolamide.
   • WHO’s inclusion of Acetazolamide as an essential medicine for glaucoma and altitude sickness.
5. American Journal of Ophthalmology. (2019). Acetazolamide in Glaucoma and Intracranial Hypertension.
   • Peer-reviewed article on the medication’s efficacy in ophthalmology (note: access may require a subscription).