METHAZOLAMIDE 25 mg Tablet, 90-count
🆔 Identity & classification
Where does this data come from?
🏷️ RxNorm drug class
This medicine belongs to the Carbonic anhydrase inhibitors class.
Where does this data come from?
🏭 Manufacturer & labeler
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🩺 Clinical
Methazolamide is used to treat glaucoma (a condition in which increased pressure in the eye can lead to gradual loss of vision). Methazolamide is in a class of medications called carbonic anhydrase inhibitors. It works by decreasing the pressure in the eye.
Read the full MedlinePlus article ↗- It's reducing the pressure inside your eye. Your eye constantly makes a fluid called aqueous humor, and methazolamide slows down how much of that fluid is produced. Less fluid mean...
- What is methazolamide actually doing for my eyes?
- The most common one people notice is a tingling or 'pins and needles' feeling in their hands and feet — it can be a little odd but it's well known with this type of drug. You might...
- What side effects should I actually expect when I start taking it?
Patient education
Supplement & herbal interactions
Some supplements/herbs that may interact with Methazolamide — tap one for details:
Methazolamide may be associated with lower levels of 7 nutrients — worth a chat with your pharmacist, not a cause for alarm.
Where does this data come from?
Ask a licensed pharmacist directly — free, answered by our team.
💊 What it looks like
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🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
💡 Tap an ingredient (hover on desktop) to see what it is and why it’s used.
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UNII O7TSZ97GEP
A mineral compound that serves as a filler and binding agent in tablets and capsules. It adds bulk to the medicine and helps hold ingredients together during manufacturing.
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UNII OP1R32D61U
Microcrystalline cellulose is a purified form of cellulose, a natural fiber from plant sources. It acts as a binder and filler in tablets and capsules, helping hold ingredients together and give the medicine its shape and size.
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UNII M28OL1HH48
Croscarmellose sodium is a plant-based substance derived from cellulose. It acts as a disintegrant, helping tablets and capsules break down quickly in the digestive system so the medicine can be absorbed.
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UNII 70097M6I30
Magnesium stearate is a salt made from magnesium and stearic acid, a fatty substance. It's used in tablets and capsules as a lubricant and glidant to help ingredients flow smoothly during manufacturing and prevent sticking.
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UNII ETJ7Z6XBU4
Silicon dioxide is a naturally occurring mineral used as a glidant and anti-caking agent. It helps powder ingredients flow smoothly and prevents clumping during manufacturing and storage.
5 inactive ingredients listed in the exact product block matched to this NDC.
Where does this data come from?
ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.Inactive ingredient FAQ
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💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per each | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | Not in the retail survey — common for institutional, discontinued, or low-volume packs. | |
| Medicaid paysCMS SDUD · 12 mo | No recent Medicaid claims on file for this NDC — rare and low-volume NDCs are suppressed in the public data. | |
| Medicare drug plans payPart D · Q2 2026 | $1.59 | $143.33 / 90 tablets |
Where does this data come from?
🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| methazolamide 25 mg 00574-0790-01 | Padagis | 100 tablets | $0.627 | AB | Availability likely | — |
| Methazolamide 25 mg 62559-0240-01 | ANI | 100 tablets | $0.627 | AB | Availability likely | — |
| Methazolamide 25 mg 68094-0908-50 | Precision | 100 tablets | $0.627 | AB | Availability likely | — |
| Methazolamide 25 mg 72603-0166-01 | NorthStar | 100 tablets | $0.627 | AB | Availability likely | — |
| Methazolamide 25 mg 24208-0022-01 | Bausch | 1000 tablets | — | AB | FDA listed | — |
| Methazolamide 25 mg 27241-0246-01 | Ajanta | 100 tablets | — | AB | FDA listed | — |
| Methazolamide 25 mgthis 42571-0239-90 | Micro | 90 tablets | — | AB | FDA listed | — |
| Methazolamide 25 mg 51407-0026-01 | Golden | 100 tablets | — | AB | FDA listed | — |
| Methazolamide 25 mg 63629-1986-01 | Bryant | 100 tablets | — | AB | FDA listed | — |
| Methazolamide 25 mg 72162-1754-01 | Bryant | 100 tablets | — | AB | FDA listed | — |
Where does this data come from?
⏳ Availability & generic status
This product is an FDA-approved generic. Other versions of the same drug are listed under Therapeutic equivalents, least expensive first.
Where does this data come from?
📊 Medicare Part D spend CMS · PART D · 2026 (Q1)
🔬 Reported adverse events (FAERS)
Top reported reactions
Age at onset
Reporter sex
Serious outcomes
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📦 Packaging — all sizes for this product
| Package NDC | Description | Marketing start | Status |
|---|---|---|---|
| 42571-0239-05 | 500 TABLET in 1 BOTTLE (42571-239-05) | 2019-03-05 | Active |
| 42571-0239-10 | 1000 TABLET in 1 BOTTLE (42571-239-10) | 2019-03-05 | Active |
| 42571-0239-90 You're viewing this | 90 TABLET in 1 BOTTLE (42571-239-90) | 2019-03-05 | Active |
You're viewing the smallest of 3 pack sizes for this product.
Pack size FAQ
What quantity is in NDC 42571-0239-90?
What is the difference between NDC 42571-0239-90 and NDC 42571-0239-05?
What NDC number is used to bill for this package of METHAZOLAMIDE 25 mg Tablet?
🧭 About this NDC listing & data coverage
What data is (and isn’t) available for this NDC — tap to expand
| NDC identity (package / product / labeler codes) | ✓ Available |
| Labeler | ✓ Available |
| Product & package description | ✓ Available |
| Marketing category & status | ✓ Available |
| Active ingredient / dosage form / route | ✓ Available |
| FDA label (SPL via DailyMed) | ✓ Available |
| Package photos | — Not published for this NDC No photo available yet for this listing. |
| Inactive ingredients (structured) | ✓ Available |
| NADAC pharmacy acquisition price (CMS) | — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey. |
| Orange Book / therapeutic-equivalence data | ✓ Available |
| HCPCS J-code billing crosswalk | — Not published for this NDC Most self-administered / retail products have no J-code — that is normal. |
| Medicaid utilization (CMS SDUD) | — Not published for this NDC CMS reports utilization only for NDCs with Medicaid claims above its privacy threshold. |
Questions about this listing
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📄 Full prescribing information FDA SPL
🎯 Indications and Usage ▾
INDICATIONS AND USAGE Methazolamide tablets 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 ▾
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 ▾
CONTRAINDICATIONS Methazolamide tablets 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 ▾
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.
🤒 Adverse Reactions ▾
ADVERSE REACTIONS 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 ).
🔄 Drug Interactions ▾
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 ).
🤰 Pregnancy ▾
Pregnancy Teratogenic effects Pregnancy category C 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.
🧒 Pediatric Use ▾
Pediatric use The safety and effectiveness of methazolamide in children have not been established.
🆘 Overdosage ▾
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.
🧬 Clinical Pharmacology ▾
CLINICAL PHARMACOLOGY Methazolamide is a potent inhibitor of carbonic anhydrase. Methazolamide is well absorbed from the gastrointestinal tract. Peak plasma concentrations are observed 1 to 2 hours after dosing.
In a multiple-dose, pharmacokinetic study, administration of methazolamide 25 mg bid, 50 mg bid, and 100 mg bid demonstrated a linear relationship between plasma methazolamide levels and methazolamide dose. Peak plasma concentrations (C max ) for the 25 mg, 50 mg and 100 mg bid regimens were 2.5 mcg/mL, 5.1 mcg/mL, and 10.7 mcg/mL, respectively. The area under the plasma concentration-time curves (AUC) was 1130 mcg.min/mL, 2571 mcg.min/mL, and 5418 mcg.min/mL for the 25 mg, 50 mg, and 100 mg dosage regimens, respectively.
Methazolamide is distributed throughout the body including the plasma, cerebrospinal fluid, aqueous humor of the eye, red blood cells, bile and extra-cellular fluid. The mean apparent volume of distribution (V area /F) ranges from 17 L to 23 L. Approximately 55% is bound to plasma proteins.
The steady-state methazolamide red blood cell:plasma ratio varies with dose and was found to be 27:1, 16:1, and 10:1 following the administration of methazolamide 25 mg bid, 50 mg bid, and 100 mg bid, respectively. The mean steady-state plasma elimination half-life for methazolamide is approximately 14 hours. At steady-state, approximately 25% of the dose is recovered unchanged in the urine over the dosing interval.
Renal clearance accounts for 20% to 25% of the total clearance of drug. After repeated bid-tid dosing, methazolamide accumulates to steady-state concentrations in 7 days. Methazolamide’s inhibitory action on carbonic anhydrase decreases the secretion of aqueous humor and results in a decrease in intraocular pressure.
The onset of the decrease in intraocular pressure generally occurs within 2 to 4 hours, has a peak effect in 6 to 8 hours and a total duration of 10 to 18 hours. 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. The drug should not be used as a diuretic. Inhibition of renal bicarbonate reabsorption produces an alkaline urine.
Plasma bicarbonate decreases, and a relative, transient metabolic acidosis may occur due to a disequilibrium in carbon dioxide transport in the red cell. Urinary citrate excretion is decreased by approximately 40% after doses of 100 mg every 8 hours. Uric acid output has been shown to decrease 36% in the first 24 hour period.
📦 How Supplied / Storage and Handling ▾
HOW SUPPLIED Methazolamide Tablets USP 25 mg: White to off-white, circular, biconvex, uncoated tablet, debossed with “25” on one side and plain on the other side. Bottles of 90 NDC 42571-239-90 Bottles of 500 NDC 42571-239-05 Bottles of 1000 NDC 42571-239-10 Methazolamide Tablets USP 50 mg: White to off-white, circular, biconvex, uncoated tablet, debossed with “50” on one side and score line on the other side. Bottles of 90 NDC 42571-240-90 Bottles of 500 NDC 42571-240-05 Bottles of 1000 NDC 42571-240-10 Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° 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 Manufactured by: Micro Labs Limited Goa- 403 722, INDIA. Manufactured for: Micro Labs USA Inc.
Basking Ridge, NJ 07920 Revised: November 2019
📋 Description ▾
DESCRIPTION Methazolamide USP, a sulfonamide derivative, is a white or faintly yellow, crystalline powder having a slight odor, soluble in dimethylformamide, slightly soluble in acetone, very slightly soluble in water and in 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: 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, and microcrystalline cellulose. structure
💬 Information for Patients ▾
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.