Fatalities have occurred, although rarely, due to severe reactions to sulfonamides
including Stevens-Johnson syndrome, toxic epider-mal 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 metha-zolamide concomitantly, as anorexia, tachypnea, lethargy, coma and death have been reported with concomitant use of high-dose aspirin and carbonic anhydrase inhibitors.
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.
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.
Carcinogenesis, Mutagenesis, Impairment of Fertility: Long-term studies
in animals to evaluate methazolamide's carcinogenic potential and its effect
on fertility have not been conducted. Methazolamide was not mutagenic in the
Ames bacterial test.
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.
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.