Reducing side effects of carbonic anhydrase inhibitors.

Carbonic anhydrase inhibitor (CAI) side effects are common, but not well understood. Many ideas have surfaced on how to reduce these side effects, even though there is little scientific evidence to support some of the advice. One recommendation involves switching drugs when patients are intolerant of a particular CAI agent. This study included 44 glaucoma patients who needed a CAI drug. All patients were placed on acetazolamide tablets 250 mg qid. Of those who could not tolerate this drug (26 patients), 22 were switched to methazolamide. Half of these 22 (50%) were considered to have "severe" side effects to methazolamide, while 88% of them had "severe" side effects to acetazolamide. Reduction of intraocular pressure was similar on the two drugs. Other than switching drugs to reduce CAI side effects, one can try reduced dosages, a gradual dosage increase, and patience. Administering sodium bicarbonate or potassium, or taking the CAI drug with meals are unproven remedies.