Brands, Medical Use, Clinical Data
- Carbonic Anhydrase Inhibitors
Brands / Synonyms
Methazolamide; Methenamide; MZM; Naptazane; Neptazane; Neptazaneat
For treatment of chronic open-angle glaucoma and acute angle-closure glaucoma
Methazolamide is topical carbonic anhydrase inhibitor. Methazolamide is indicated for the reduction of elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension who are insufficiently responsive to beta-blockers. Methazolamide is a sulfonamide derivative; however, it does not have any clinically significant antimicrobial properties. Although methazolamide achieves a high concentration in the cerebrospinal fluid, it is not-considered an effective anticonvulsant. Methazolamide has a weak and transient diuretic effect, therefore use results in an increase in urinary volume, with excretion of sodium, potassium and chloride.
Mechanism of Action
Methazolamide is a potent inhibitor of carbonic anhydrase. Inhibition of carbonic anhydrase in the ciliary processes of the eye decreases aqueous humor secretion, presumably by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport.
Methazolamide is well absorbed from the gastrointestinal tract.
Electrolyte imbalance, development of an acidotic state, and central nervous system effects might be expected to occur in the case of an overdose.
Biotrnasformation / Drug Metabolism
Methazolamide therapy is contraindicated in situations in which sodium and/or potassium serum levels are
depressed, in cases of marked kidney or liver disease or dysfunction, in adrenal gland failure, and in hyperchloremic
acidosis. In patients with cirrhosis, use may precipitate the development of hepatic encephalopathy.
Long-term administration of methazolamide is contraindicated in patients with angle-closure glaucoma, since
organic closure of the angle may occur in spite of lowered intraocular pressure.
Methazolamide should be used with caution in patients on steroid therapy because of the potential for developing
Caution is advised for patients receiving high-dose aspirin and methazolamide concomitantly, as anorexia,
tachypnea, lethargy, coma and death have been reported with concomitant use of high-dose aspirin and carbonic