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Neptazane (Methazolamide)

Diuretic, Glaucoma treatment, Urinary alkalinizing agent, Carbonic Anhydrase Inhibitor, Potassium Depleting Diuretic

Brand Names

GlaucTabs®, Neptazane®

Drug Information

Pharmacology

Carbonic anhydrase inhibitor – results in decreased formation of aqueous humor.

Contraindications

General
  • Contraindicated in animals with sulfonamide hypersensitivity
  • Contraindicated in patients with hepatic disease – may precipitate hepatic coma.
  • Contraindicated in patients with renal or adrenocortical insufficiency
  • Contraindicated in patients with electrolyte disorders, hyponatremia, hypokalemia, hyperchloremic acidosis.
  • Contraindicated in pulmonary obstructive disorders
  • Contraindicated in angle closure glaucoma-long term use in these cases can cause angle closure and mask symptoms by reducing intraocular pressure.
  • Contraindicated in pre existing hematologic disorders or respiratory acidosis
  • Caution in diabetics or obstructive pulmonary disease

Adverse Effects

General
  • Vomiting, diarrhea, CNS effects- sedation, depression, excitement and bone marrow suppression are possible.
  • Renal effects-crystalluria, dysuria, polyuria and polydipsia, hypokalemia, hyponatremia, hyperglycemia, hyperuricosemia are also possible.
  • Hepatic insufficiency, dermatologic effects – rash, pruritus, hypersensitivity reactions and death are all possible side effects.

Interactions

Category Interactions
Corticosteroid
  • May exacerbate potassium depletion.
Diuretic
  • May exacerbate potassium depletion.
Drug Interactions
Amphotericin B
  • May exacerbate potassium depletion.
Corticotropin (ACTH)
  • May exacerbate potassium depletion.
Digoxin
  • May exacerbate potassium depletion.
Dorzolamide (Ophthalmic)
  • Topical dorzolamide does not have additive benefit and may increase the risk for side effects.
Insulin
  • May affect the hypoglycemic effect of insulin.
Methenamine
  • May negate the effects of methenamine in the urine.
Methotrexate
  • Excretion rate may be affected.
PHENobarbital
  • Excretion rate may be affected.
Phenytoin sodium
  • May cause severe osteomalacia.
Primidone
  • Absorption may be inhibited and may result in osteomalacia.
Procainamide
  • Excretion rate may be affected.
QuiNIDine
  • Excretion rate may be affected.

Comments

Monitor intraocular pressure if used for glaucoma, blood gases if used for alkalosis, serum electrolytes, baseline CBC and differential with periodic retest if chronic use.

Available Forms

Human
  • Tablets – 25 and 50 mg; Neptazane ®, GlaucTabs ®, generic.
Veterinary – General
  • None