No

Carbonic Anhydrase Inhibitor; Diuretic, Carbonic Anhydrase Inhibitor; Ophthalmic Agent, Antiglaucoma

Adjunctive treatment of open-angle or secondary glaucoma; short-term therapy of narrow-angle glaucoma when delay of surgery is desired

C

Marked kidney or liver dysfunction, severe pulmonary obstruction, hypersensitivity to methazolamide or any component

Sulfonamide-type reactions, melena, anorexia, nausea, vomiting, constipation, hematuria, glycosuria, urinary frequency, renal colic, renal calculi, crystalluria, polyuria, hepatic insufficiency, various CNS effects, transient myopia, bone marrow suppression, thrombocytopenia/purpura, hemolytic anemia, leukopenia, pancytopenia, agranulocytosis, urticaria, pruritus, rash, Stevens-Johnson syndrome, weight loss, fever, acidosis; use with caution in patients with respiratory acidosis and diabetes mellitus; impairment of mental alertness and/or physical coordination. Malaise and complaints of tiredness and myalgia are signs of excessive dosing and acidosis in the elderly.

>10%:

Central nervous system: Malaise

Gastrointestinal: Metallic taste, anorexia

Genitourinary: Polyuria

Neuromuscular & skeletal: Weakness

1% to 10%:

Central nervous system: Mental depression, drowsiness, dizziness

Genitourinary: Crystalluria

<1%: Fever, headache, seizures, fatigue, rash, sulfonamide rash, Stevens-Johnson syndrome, hyperchloremic metabolic acidosis, hypokalemia, hyperglycemia, GI irritation, constipation, xerostomia, black tarry stools, bone marrow suppression, dysuria, paresthesia, trembling, unsteadiness, myopia, tinnitus, loss of smell, hypersensitivity

Increased toxicity:

May induce hypokalemia which would sensitize a patient to digitalis toxicity

May increase the potential for salicylate toxicity

Hypokalemia may be compounded with concurrent diuretic use or steroids

Primidone absorption may be delayed

Decreased effect: Increased lithium excretion and altered excretion of other drugs by alkalinization of the urine, such as amphetamines, quinidine, procainamide, methenamine, phenobarbital, salicylates

Noncompetitive inhibition of the enzyme carbonic anhydrase; thought that carbonic anhydrase is located at the luminal border of cells of the proximal tubule. When the enzyme is inhibited, there is an increase in urine volume and a change to an alkaline pH with a subsequent decrease in the excretion of titratable acid and ammonia.

Onset of action: Slow in comparison with acetazolamide (2-4 hours)

Peak effect: 6-8 hours

Duration: 10-18 hours

Absorption: Slowly from GI tract

Distribution: Distributes well into tissue

Protein binding: ~55%

Half-life: ~14 hours

Elimination: ~25% excreted unchanged in urine

Adults: Oral: 50-100 mg 2-3 times/day

Sedation is common; may cause dizziness or depression

May rarely cause bone marrow suppression; use caution with clozapine and carbamazepine; may increase lithium excretion but overall effect is minimal; if lithium toxicity is severe, hemodialysis is the treatment of choice

No information available to require special precautions

No effects or complications reported

Take with food; swallow whole, do not chew or crush. You may experience gastrointestinal upset and loss of appetite; frequent small meals are advised to reduce these effects and the metallic taste that sometimes occurs with this medication. You may experience lightheadedness, depression, dizziness, or weakness for a few days; use caution when driving or engaging in tasks that require alertness until response to drug is known. Report excessive tiredness; loss of appetite; cramping, pain, or weakness in muscles; acute GI symptoms; changes in CNS (depression, drowsiness); difficulty or pain on urination; visual changes; or skin rash. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to be pregnant. Consult prescriber if breast-feeding.

May cause an alteration in taste, especially when drinking carbonated beverages

Tablet: 25 mg, 50 mg