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methazolamide (meth-a-zole-a-mide)

GlaucTabs, Neptazane


Therapeutic: diuretics

Pharmacologic: carbonic anhydrase inhibitors


Lowering of intraocular pressure in the treatment of glaucoma.


Inhibition of carbonic anhydrase in the eye results in decreased secretion of aqueous humor. Inhibit renal carbonic anhydrase, resulting in self-limiting urinary excretion of sodium, potassium, bicarbonate, and water. Therapeutic Effects: Lowering of intraocular pressure.

Adverse Reactions/Side Effects

CNS: depression, tiredness, weakness, drowsiness. EENT: transient nearsightedness. GI: anorexia, metallic taste, nausea, vomiting. GU: crystalluria, renal calculi. Derm: rashes. Endo: hyperglycemia. F and E: hyperchloremic acidosis, hypokalemia. Hemat: APLASTIC ANEMIA, HEMOLYTIC ANEMIA, LEUKOPENIA. Metab: weight loss, hyperuricemia. Neuro: paresthesias. Misc: allergic reactions.


Examination and Evaluation

  • Monitor signs of leukopenia (fever, sore throat, signs of infection) or various anemias (unusual fatigue, shortness of breath, dizziness, headache, coldness in your hands and feet, pale skin, chest pain, bruising). Report these signs to the physician immediately.

  • Monitor signs of fluid, electrolyte, or acid-base imbalances, including dizziness, drowsiness, blurred vision, confusion, hypotension, or muscle cramps and weakness. Report excessive or prolonged symptoms to the physician.

  • Monitor signs of allergic reactions, including pulmonary symptoms (tightness in the throat and chest, wheezing, cough, dyspnea) or skin reactions (rash, pruritus, urticaria). Notify physician or nursing staff immediately if these reactions occur.

  • Be alert for signs of hyperglycemia, including confusion, drowsiness, flushed/dry skin, fruit-like breath odor, rapid/deep breathing, polyuria, loss of appetite, and unusual thirst. Patients with diabetes mellitus should check blood glucose levels frequently.

  • Assess signs of paresthesia such as numbness, tingling, and muscle weakness. Perform objective tests, including electroneuromyography and sensory testing to document any drug-related neuropathic changes.

  • Monitor and report depression or other changes in mood and behavior.


  • Implement fall-prevention strategies, especially in older adults or if patient exhibits weakness, tiredness, drowsiness, nearsightedness, or other impairments that affect gait and balance (See Appendix E).

Patient/Client-Related Instruction

  • Instruct patient to report any problems with urination or signs of renal calculi (kidney stones) such as severe pain in the side and back, pain on urination, bloody urine, and a persistent urge to urinate.

  • Instruct patient to report other bothersome side effects such as severe or prolonged skin rash or GI problems (nausea, vomiting, metallic taste).


Absorption: Well absorbed after oral administration.

Distribution: Crosses the placenta.

Metabolism and Excretion: 15–30% excreted unchanged in urine.

Half-life: 14 hr.

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TIME/ACTION PROFILE (lowering of intraocular pressure)


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