methazolamide (Rx)

>10%

Drowsiness

Paresthesias

Anorexia

Nausea

Vomiting

Frequency Not Defined

Sulfonamide-type rxns

Acidosis

Electrolyte imbalance

Glycosuria

Hematuria

Thrombocytopenia

Hepatic dysfunction

Tinnitus

Contraindications

Hypokalemia, hyponatremia, hyperchloremic acidosis, cirrhosis, severe liver or renal impairment, adrenal gland failure

Cautions

COPD, emphysema, concomitant high-dose aspirin or steroid therapy, or hepatic insufficiency

ADRs common to sulfonamide derivatives

Stevens-Johnson syndrome and toxic epidermal necrolysis may occur

Pregnancy Category: C

Lactation: not known if crosses in to breast milk, avoid

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

Mechanism of Action

Carbonic anhydrase inhibitor, decr rate of aqueous humor formation and decreased IOP

Pharmacokinetics

Half-life: 14 d

Onset: 2-4 hr

Max Effect: 6-8 hr

Duration: 10-18 hr

Bioavailability: absorbed more slowly than acetazolamide

Excretion: urine 15%