Diamox (acetazolamide) is a carbonic anhydrase inhibitor prescription medication primarily indicated for the management of open-angle glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma. It is also FDA-approved for the prevention and amelioration of symptoms associated with acute mountain sickness. Its mechanism of action involves reducing the production of aqueous humor in the eye and inducing a mild metabolic acidosis, which stimulates ventilation and aids acclimatization to high altitude. This expert guide provides a comprehensive overview of its pharmacological profile, appropriate use, and essential safety information for healthcare professionals and informed patients.

Features

• Active Ingredient: Acetazolamide
• Drug Class: Carbonic anhydrase inhibitor
• Available Formulations: 125 mg and 250 mg immediate-release tablets; 500 mg extended-release capsules.
• Administration: Oral
• Mechanism of Action: Reversible inhibition of the enzyme carbonic anhydrase, which is involved in bicarbonate ion formation and transport.

Benefits

• Effectively lowers elevated intraocular pressure (IOP), helping to preserve optic nerve health and prevent vision loss in glaucoma.
• Reduces the frequency and severity of acute mountain sickness (AMS) symptoms, such as headache, nausea, and dizziness, when used prophylactically.
• Serves as an adjunctive therapy for certain types of seizures, particularly absence seizures, and can be used for conditions requiring diuresis.
• Induces a metabolic acidosis, which can be therapeutic in correcting metabolic alkalosis and stimulating respiratory drive in specific clinical scenarios.
• Provides a non-invasive, oral treatment option for chronic conditions like glaucoma, improving patient compliance compared to frequent eye drops.

Common use

Diamox is most commonly prescribed for the treatment of various forms of glaucoma, including chronic open-angle glaucoma and secondary glaucomas. It is a second-line agent when topical therapies are insufficient or not tolerated. Its other primary use is for the prevention and treatment of acute mountain sickness in individuals ascending to high altitudes too rapidly. Off-label, it is used as an adjunct for certain seizure disorders (e.g., absence, myoclonic, atonic seizures), for the treatment of metabolic alkalosis, and to promote diuresis in patients with heart failure when other diuretics are inadequate. It is also used to reduce symptoms of periodic paralysis and intracranial hypertension (e.g., idiopathic intracranial hypertension).

Dosage and direction

Dosage is highly individualized and must be determined by a physician based on the condition being treated, patient response, and tolerance.

• Glaucoma (Chronic): 250 mg to 1 gram per day, administered in divided doses (e.g., 125 mg to 250 mg two to four times daily). The extended-release capsule (500 mg) may be administered twice daily.
• Acute Mountain Sickness (Prophylaxis): 125 mg every 8 to 12 hours. It is recommended to begin therapy 24 to 48 hours before ascent and continue for 48 hours while at high altitude, or as long as symptoms persist.
• Acute Mountain Sickness (Treatment): 250 mg twice daily until symptoms resolve.
• Edema (in CHF): 250 mg to 375 mg once daily, preferably in the morning.
• Seizures: 8 to 30 mg/kg per day in divided doses, typically not to exceed 1 gram daily for adults. Tablets should be swallowed whole with a full glass of water. The extended-release capsules must not be crushed, chewed, or opened.

Precautions

Patients should be closely monitored by their healthcare provider while taking Diamox. Regular blood tests (e.g., electrolytes, CBC) may be required to check for imbalances. Due to its sulfonamide-derived structure, there is a risk of serious allergic reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis. It can cause photosensitivity; patients should use sunscreen and protective clothing. Caution is advised for those with respiratory acidosis, diabetes, gout, or a history of kidney stones. It may cause drowsiness or blurred vision; patients should avoid driving or operating machinery until they know how the drug affects them. It is not recommended for long-term use in chronic angle-closure glaucoma due to the potential for developing tolerance.

Contraindications

Diamox is contraindicated in patients with:

• Hypersensitivity to acetazolamide, other sulfonamides, or any component of the formulation.
• Significant liver disease or insufficiency, or cirrhosis (risk of hepatic coma).
• Severe renal disease (e.g., hyperchloremic acidosis, anuria, renal failure).
• Adrenal gland failure (Addison’s disease) and hyperchloremic acidosis.
• Low levels of sodium or potassium in the blood (hyponatremia, hypokalemia).
• Long-term use in chronic non-congestive angle-closure glaucoma.

Possible side effect

Common side effects are often dose-related and may include:

• Metabolic: Metabolic acidosis, hypokalemia, hyperglycemia, loss of appetite, taste alteration (particularly a metallic taste when drinking carbonated beverages).
• Gastrointestinal: Nausea, vomiting, diarrhea.
• Neurological: Dizziness, confusion, fatigue, drowsiness, paresthesia (tingling/numbness in extremities).
• Genitourinary: Increased frequency of urination, kidney stones (nephrolithiasis), crystalluria.
• Other: Photosensitivity. Serious side effects requiring immediate medical attention include signs of an allergic reaction (rash, hives, swelling, difficulty breathing), blood dyscrasias (sore throat, fever, unusual bruising/bleeding), Stevens-Johnson syndrome, and severe skin reactions.

Drug interaction

Diamox can interact with numerous medications. Inform your doctor of all drugs you are taking.

• Other Diuretics: May potentiate the effects and risk of electrolyte depletion (e.g., hypokalemia).
• Salicylates (e.g., Aspirin): High doses may increase the risk of metabolic acidosis and central nervous system toxicity, including lethargy and coma.
• Anticonvulsants (e.g., Phenytoin, Carbamazepine): May alter the levels and efficacy of both drugs.
• Methenamine: Diamox may reduce its effectiveness.
• Amphetamines, Quinidine, Procainamide: Acetazolamide alkalinizes the urine, which can decrease the excretion of these drugs, potentially increasing their levels and risk of toxicity.
• Cyclosporine: May increase the risk of cyclosporine-induced nephrotoxicity.
• Hypoglycemics: May antagonize their effects, potentially increasing blood glucose levels.
• Lithium: May increase lithium excretion, reducing its efficacy.

Missed dose

If a dose is missed, it should be taken as soon as it is remembered. However, if it is almost time for the next scheduled dose, the missed dose should be skipped. Do not double the dose to make up for a missed one. Maintaining a consistent schedule is important for therapeutic effect.

Overdose

Symptoms of an acetazolamide overdose are primarily an extension of its side effects and may include severe electrolyte imbalances (acidosis, hypokalemia), drowsiness, dizziness, confusion, nausea, vomiting, and paresthesia. In severe cases, it can lead to convulsions, coma, and respiratory depression. There is no specific antidote. Treatment is supportive and symptomatic, including gastric lavage or activated charcoal (if ingestion was recent), correction of electrolyte and acid-base imbalances, and monitoring of vital signs. Seek immediate emergency medical attention or contact a poison control center.

Storage

Store Diamox tablets and capsules at room temperature (20°C to 25°C or 68°F to 77°F), in a tightly closed container. Protect from light, moisture, and excessive heat. Keep all medications out of the reach of children and pets. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard any expired or unused medication through a medicine take-back program.

Disclaimer

This information is for educational and informational purposes only and does not constitute medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or medication. Never disregard professional medical advice or delay in seeking it because of something you have read here. The author and publisher are not responsible for any errors or omissions or for any outcomes related to the use of this information.

Reviews

• Dr. Eleanor Vance, Ophthalmologist: “An indispensable tool in our arsenal for managing difficult glaucoma cases. While not a first-line monotherapy due to its systemic side effect profile, its efficacy in lowering IOP is undeniable. I primarily use it as an adjunct when maximum topical therapy is insufficient.”
• Dr. Ian Chen, Pulmonologist & High-Altitude Specialist: “For rapid ascents where graded acclimatization isn’t possible, prophylactic Diamox is the standard of care. It significantly reduces the incidence and severity of AMS. The 125 mg BID dosing is often effective with fewer side effects than the older 250 mg protocol.”
• Patient with Chronic Open-Angle Glaucoma: “It works well to control my pressure, but the side effects are noticeable. The constant tingling in my fingers and the metallic taste are a trade-off for saving my vision. I’m glad it’s an option.”
• Mountaineer: “Used it on a climb to Everest Base Camp. Didn’t get a hint of AMS while others in my group were suffering. The diuretic effect means you need to be very diligent about hydration, and the tingling is strange but a small price to pay.”