From the Guidelines
Carbonic anhydrase inhibitors, such as acetazolamide, zonisamide, and topiramate, are used to treat various conditions, including obstructive sleep apnea, glaucoma, altitude sickness, seizures, and idiopathic intracranial hypertension. These medications work by blocking the enzyme carbonic anhydrase, which is responsible for converting carbon dioxide and water to bicarbonate and hydrogen ions, thereby affecting fluid balance in various tissues and leading to their therapeutic effects 1.
Key Uses and Effects
- Reduce sleep apnea intensity (AHI) by up to 45% in unselected groups of patients, as seen in studies using acetazolamide, zonisamide, and topiramate 1
- Improve sleep efficiency and reduce oxygen desaturation index, as suggested by sleep studies on carbonic anhydrase inhibitors 1
- Treat glaucoma by reducing intraocular pressure, as they decrease the production of aqueous humor in the eye
- Prevent and treat altitude sickness, certain types of seizures, and as diuretics for conditions like heart failure and idiopathic intracranial hypertension
Medication Examples
- Acetazolamide (Diamox)
- Zonisamide
- Topiramate (Topamax)
- Methazolamide (Neptazane)
- Dorzolamide (Trusopt)
- Brinzolamide (Azopt)
Administration and Side Effects
- Available as oral medications or eye drops (dorzolamide, brinzolamide) for direct ocular application
- Common side effects include tingling in extremities, altered taste sensation, fatigue, and potential electrolyte imbalances
- Patients with sulfa allergies should use these medications cautiously as cross-reactivity may occur 1.
From the FDA Drug Label
Acetazolamide is a potent carbonic anhydrase inhibitor, effective in the control of fluid secretion (e.g., some types of glaucoma), in the treatment of certain convulsive disorders (e.g., epilepsy) and in the promotion of diuresis in instances of abnormal fluid retention (e.g., cardiac edema). Methazolamide is a potent inhibitor of carbonic anhydrase. Methazolamide’s inhibitory action on carbonic anhydrase decreases the secretion of aqueous humor and results in a decrease in intraocular pressure.
Carbonic Anhydrase Inhibitors are used for:
- Controlling fluid secretion in conditions like glaucoma
- Treating certain convulsive disorders such as epilepsy
- Promoting diuresis in cases of abnormal fluid retention, like cardiac edema Examples of carbonic anhydrase inhibitors include:
- Acetazolamide 2
- Methazolamide 3
From the Research
Carbonic Anhydrase Inhibitors
- Carbonic anhydrase inhibitors (CAIs) are a class of medications that have various applications, including the treatment of glaucoma, acute mountain sickness, and epilepsy 4, 5, 6.
Examples of Carbonic Anhydrase Inhibitors
- First generation CAIs:
- Acetazolamide
- Methazolamide
- Dichlorophenamide
- Second generation CAIs:
- Dorzolamide
- Brinzolamide
Uses of Carbonic Anhydrase Inhibitors
- Treatment of glaucoma: CAIs are used to reduce intraocular pressure (IOP) by decreasing aqueous humor production 4, 7, 8.
- Prevention and treatment of acute mountain sickness: CAIs, particularly acetazolamide, are used to prevent or reduce symptoms of acute mountain sickness by increasing ventilation and arterial oxygenation 5.
- Treatment of epilepsy: Acetazolamide is used as an antiepileptic agent, although its use is limited due to perceived poor efficacy and adverse events 6.