Methazolamide
Tablet · Oral
Uses
Methazolamide Tablets, USP are indicated in the treatment of ocular conditions where lowering intraocular pressure is likely to be of therapeutic benefit, such as chronic open-angle glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma where lowering the intraocular pressure is desired before surgery.
Dosage and administration
The effective therapeutic dose administered varies from 50 mg to 100 mg two or three times daily. The drug may be used concomitantly with miotic and osmotic agents.
Contraindications
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.
Warnings
Fatalities have occurred, although rarely, due to severe reactions to sulfonamides including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias. Hypersensitivity reactions may recur when a sulfonamide is readministered, irrespective of the route of administration. If hypersensitivity or other serious reactions occur, the use of this drug should be discontinued. 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 anhydrase inhibitors.
Precautions
General Potassium excretion is increased initially upon administration of methazolamide and in patients with cirrhosis or hepatic insufficiency could precipitate a hepatic coma. In patients with pulmonary obstruction or emphysema, where alveolar ventilation may be impaired, methazolamide should be used with caution because it may precipitate or aggravate acidosis. Information for Patients Adverse reactions common to all sulfonamide derivatives may occur: anaphylaxis, fever, rash (including erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), crystalluria, renal calculus, bone marrow depression, thrombocytopenic purpura, hemolytic anemia, leukopenia, pancytopenia, and agranulocytosis. Precaution is advised for early detection of such reactions, and the drug should be discontinued and appropriate therapy instituted. Caution is advised for patients receiving high-dose aspirin and methazolamide concomitantly. Laboratory Tests To monitor for hematologic reactions common to all sulfonamides, it is recommended that a baseline CBC and platelet count be obtained on patients prior to initiating methazolamide therapy and at regular intervals during therapy. If significant changes occur, early discontinuance and institution of appropriate therapy are important. Periodic monitoring of serum electrolytes is also recommended. Drug Interactions Methazolamide should be used with caution in patients on steroid therapy because of the potential for developing hypokalemia. 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 anhydrase inhibitors (see WARNINGS ). Carcinogenesis, Mutagenesis, Impairment of Fertility Long-term studies in animals to evaluate the carcinogenic potential of methazolamide and its effect on fertility have not been conducted. Methazolamide was not mutagenic in the Ames bacterial test. Pregnancy Teratogenic effects. Methazolamide has been shown to be teratogenic (skeletal anomalies) in rats when given in doses approximately 40 times the human dose. There are no adequate and well controlled studies in pregnant women. Methazolamide should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Nursing Mothers It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from methazolamide, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. Pediatric Use The safety and effectiveness of methazolamide in children have not been established.
Side effects
Adverse reactions, occurring most often early in therapy, include paresthesias, particularly a “tingling” feeling in the extremities; hearing dysfunction or tinnitus; fatigue; malaise; loss of appetite; taste alteration; gastrointestinal disturbances such as nausea, vomiting, and diarrhea; polyuria; and occasional instances of drowsiness and confusion. Metabolic acidosis and electrolyte imbalance may occur. Transient myopia has been reported. This condition invariably subsides upon diminution or discontinuance of the medication. Other occasional adverse reactions include urticaria, melena, hematuria, glycosuria, hepatic insufficiency, flaccid paralysis, photosensitivity, convulsions, and, rarely, crystalluria and renal calculi. Also see PRECAUTIONS: Information for Patients for possible reactions common to sulfonamide derivatives. Fatalities have occurred, although rarely, due to severe reactions to sulfonamides including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias (see WARNINGS ).
Overdosage
No data are available regarding methazolamide overdosage in humans as no cases of acute poisoning with this drug have been reported. Animal data suggest that even a high dose of methazolamide is nontoxic. No specific antidote is known. Treatment should be symptomatic and supportive. Electrolyte imbalance, development of an acidotic state, and central nervous system effects might be expected to occur. Serum electrolyte levels (particularly potassium) and blood pH levels should be monitored. Supportive measures may be required to restore electrolyte and pH balance.
Description
Methazolamide USP, a sulfonamide derivative, is a white or faintly yellow, crystalline powder, weakly acidic, slightly soluble in acetone, very slightly soluble in water and alcohol. The chemical name for methazolamide is: N-[5-(aminosulfonyl)-3-methyl-1,3,4-thiadiazol-2(3H)-ylidene]-acetamide and it has the following structural formula: C 5 H 8 N 4 O 3 S 2 236.27 Each tablet, for oral administration, contains 25 mg or 50 mg methazolamide USP. In addition, each tablet contains the following inactive ingredients: colloidal silicon dioxide, croscarmellose sodium, dibasic calcium phosphate dihydrate, magnesium stearate (powder), and microcrystalline cellulose. structure
How supplied
Methazolamide Tablets, USP 25 mg are round, off-white to white, biconvex, uncoated tablets, debossed with “M1” on one side and plain on the other side and are supplied in bottles of 100 with child-resistant closure, NDC 27241-246-01. Methazolamide Tablets, USP 50 mg are round, off-white to white, flat beveled edged, uncoated scored tablets, debossed with “M2” on one side and break line on the other side and are supplied in bottles of 100 with child-resistant closure, NDC 27241-247-01. Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F) [see USP Controlled Room temperature]. Dispense in a tight container as defined in the USP, with a child-resistant closure (as required). Rx only Product of India Manufactured by: Ajanta Pharma Limited, India Marketed by: Ajanta Pharma USA Inc. Bridgewater, NJ 08807. Revised: 02/2026
Label text from the FDA structured product label by Ajanta Pharma USA Inc. (revised Feb 10, 2026). Long sections are shortened; the complete label is on DailyMed.
Active ingredients
- Methazolamide in 20 products
Methazolamide NDC products (20)
| NDC | Strength & form | Labeler | Type |
|---|---|---|---|
| 27241-246 | Methazolamide 25 mg/1 Tablet | Ajanta Pharma USA Inc. | ANDA |
| 27241-247 | Methazolamide 50 mg/1 Tablet | Ajanta Pharma USA Inc. | ANDA |
| 62559-240 | Methazolamide 25 mg/1 Tablet | ANI Pharmaceuticals, Inc. | ANDA |
| 62559-241 | Methazolamide 50 mg/1 Tablet | ANI Pharmaceuticals, Inc. | ANDA |
| 24208-022 | Methazolamide 25 mg/1 Tablet | Bausch & Lomb Incorporated | ANDA |
| 24208-023 | Methazolamide 50 mg/1 Tablet | Bausch & Lomb Incorporated | ANDA |
| 63629-1986 | Methazolamide 25 mg/1 Tablet | Bryant Ranch Prepack | ANDA |
| 63629-1987 | Methazolamide 50 mg/1 Tablet | Bryant Ranch Prepack | ANDA |
| 72162-1755 | Methazolamide 50 mg/1 Tablet | Bryant Ranch Prepack | ANDA |
| 72162-1754 | Methazolamide 25 mg/1 Tablet | Bryant Ranch Prepack | ANDA |
| 51407-026 | Methazolamide 25 mg/1 Tablet | Golden State Medical Supply, Inc. | ANDA |
| 51407-027 | Methazolamide 50 mg/1 Tablet | Golden State Medical Supply, Inc. | ANDA |
| 42571-239 | Methazolamide 25 mg/1 Tablet | Micro Labs Limited | ANDA |
| 42571-240 | Methazolamide 50 mg/1 Tablet | Micro Labs Limited | ANDA |
| 72603-167 | Methazolamide 50 mg/1 Tablet | NorthStar Rx LLC | ANDA |
| 72603-166 | Methazolamide 25 mg/1 Tablet | NorthStar Rx LLC | ANDA |
| 0574-0791 | Methazolamide 50 mg/1 Tablet | Padagis US LLC | ANDA |
| 0574-0790 | Methazolamide 25 mg/1 Tablet | Padagis US LLC | ANDA |
| 68094-908 | Methazolamide 25 mg/1 Tablet | Precision Dose, Inc. | ANDA |
| 68094-808 | Methazolamide 50 mg/1 Tablet | Precision Dose, Inc. | ANDA |
Frequently asked questions
What is Methazolamide used for?
Methazolamide Tablets, USP are indicated in the treatment of ocular conditions where lowering intraocular pressure is likely to be of therapeutic benefit, such as chronic open-angle glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma where lowering the intraocular pressure is desired before surgery.
What are the side effects of Methazolamide?
Adverse reactions, occurring most often early in therapy, include paresthesias, particularly a “tingling” feeling in the extremities; hearing dysfunction or tinnitus; fatigue; malaise; loss of appetite; taste alteration; gastrointestinal disturbances such as nausea, vomiting, and diarrhea; polyuria; and occasional instances of drowsiness and confusion. Metabolic acidosis and electrolyte imbalance… See the full label for the complete list.
Who makes Methazolamide?
Methazolamide is listed by 9 labelers in the FDA NDC directory, including Ajanta Pharma USA Inc., ANI Pharmaceuticals, Inc., Bausch & Lomb Incorporated, Bryant Ranch Prepack.