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methazolamide (Neptazane)
Tradename: Neptazane.
Indications:
1) adjunctive treatment of open angle or secondary glaucoma
2) short-term treatment of narrow-angle glaucoma when delay of surgery is indicated
3) open-angle glaucoma [4]
Dosage: 50-100 mg PO BID/TID
Tabs: 25 mg, 50 mg.
Pharmacokinetics:
1) absorbed slowly from the GI tract
2) distributed into many body tissues
3) partially metabolized by liver
4) 20-30% of the drug is excreted in the urine
Adverse effects:
1) common (> 10%)
- metallic taste, anorexia, increased urination, malaise, weakness
2) less common (1-10%)
- crystalluria, depression, drowsiness, dizziness
3) uncommon (< 1%)
- loss of smell, headache, constipation, trembling, tinnitus, myopia, hypokalemia, hypersensitivity, seizures, unsteadiness, melena, paresthesias, fatigue, fever, rash*, metabolic acidosis, hyperglycemia, GI irritation, dry mouth, bone marrow suppression, dysuria, Stevens-Johnson syndrome
4) other
- nausea/vomiting
- diarrhea
- sedation
- sulfonamide hypersensitivity reactions
- decrease in uric acid secretion
- bone marrow suppression (rare)
- aplastic anemia
- thrombocytopenia
- leukopenia
- agranulocytosis
- hemolytic anemia
* rash may be due to sulfa allergy
Drug interactions:
1) methazolamide increases lithium excretion
2) alkalinzation of urine may decrease excretion of:
a) amphetamines
b) procainamide
c) quinidine
d) tricyclic antidepressants
3) enhanced diuretic activity in combination with other diuretics
Mechanism of action:
1) inhibitor of carbonic anhydride
2) diuretic useful for alkalinization of urine
3) decreases formation of aqueous humor
4) lowers intraocular pressure
Interactions
drug interactions
drug adverse effects (more general classes)
monitor with carbonic anhydrase inhibitors
General
carbonic anhydrase inhibitor
sulfonamide
Properties
INHIBITS: carbonic anhydrase (dehydratase)
MISC-INFO: elimination route LIVER
KIDNEY
Database Correlations
PUBCHEM cid=4100
References
- The Pharmacological Basis of Therapeutics, 8th ed.
Gilman et al, eds. Permagon Press/McGraw Hill pg 716
- The Pharmacological Basis of Therapeutics, 9th ed.
Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
- Deprecated Reference