Classifications: eye preparation; carbonic anhydrase inhibitor; sulfonamide derivative; antiglaucoma; Therapeutic: antiglaucoma; carbonic anhydrase inhibitor
Pregnancy Category: C
25 mg, 50 mg tablets
Inhibits carbonic anhydrase activity in eye by reducing rate of aqueous humor formation with consequent lowering of intraocular
Effective in lowering intraocular pressure in glaucoma patients.
Adjunctive treatment in chronic simple (open-angle) glaucoma and secondary glaucoma and preoperatively in acute angle-closure
glaucoma when delay of surgery is desired in order to lower intraocular pressure. May be used concomitantly with miotic
and osmotic agents.
Glaucoma due to severe peripheral anterior synechiae, severe or absolute glaucoma, hemorrhagic glaucoma; hypokalemia, hyponatremia;
dialysis; hepatic disease; renal disease, anuria, renal failure; pregnancy (category C).
Pulmonary disease, COPD; diabetes mellitus; renal impairment; lactation.
Route & Dosage
Adult: PO 50100 mg b.i.d. or t.i.d.
- Give with meals to minimize GI distress.
Adverse Effects (≥1%) Body as a Whole: Malaise
, drowsiness, fatigue
, lethargy. GI:
Mild GI disturbance, anorexia. CNS:
Headache, vertigo, paresthesias, mental confusion, depression
excretion of amphetamines
, ephedrine, flecainide, quinidine, procainamide, tricyclic antidepressants
may be decreased, thereby enhancing or prolonging their effects; increases renal
excretion of lithium;
excretion of phenobarbital
may be increased; amphotericin B, corticosteroids
may add to potassium loss; hypokalemia caused by methazolamide may predispose patients on digitalis glycosides
to digitalis toxicity
; patients on high doses of salicylates
are at higher risk for salicylate toxicity
Slowly from GI tract. Onset:
24 h. Peak:
68 h. Duration:
1018 h. Distribution:
throughout body, concentrating in RBCs, plasma
, and kidneys; crosses placenta. Metabolism:
Partially in liver. Elimination:
Primarily in urine.
Assessment & Drug Effects
- Supervise ambulation in older adult, since drug may cause vertigo.
- Assess patient's ability to perform ADL since drug may cause fatigue and lethargy.
- Lab tests: Obtain periodic serum electrolytes, especially in older adults. Monitor lithium levels with concurrent administration
of lithium and methazolamide.
Patient & Family Education
- Be aware that drug may cause drowsiness. Advise caution with hazardous activities until response to drug is known.