Methazolamide (oral)
Orals / systemic · Rx
Trade namesNeptazane
Drug classSystemic carbonic anhydrase inhibitor
Strength25 / 50 mg tablets
AvailabilityRx
Mechanism of actionSystemic CAI; longer half-life and less renal effect than acetazolamide, so fewer stones and less hypokalemia, but similar paresthesias and malaise.
Indication / reason for useChronic adjunctive IOP lowering when a systemic CAI is needed and acetazolamide is poorly tolerated.
Usual adult dosing25-50 mg two or three times daily.
PreservativeN/A , a preservative-free option exists
Contact lensesNo lens restriction.
Common / important adverse effectsParesthesias, fatigue, GI upset, taste disturbance, drowsiness; blood dyscrasias and SJS as a class.
Contraindications & cautionsSulfonamide hypersensitivity, hepatic/renal failure, low sodium/potassium, adrenal insufficiency, marked acidosis.
Pregnancy / lactationAvoid.
Practice notesBetter tolerated than acetazolamide for the rare patient who needs long-term oral CAI therapy.
Chair-side reference only. Dosing, contraindications and pregnancy guidance here are not exhaustive. Confirm against the current prescribing information and the patient’s full history before prescribing or advising.