Na or K depletion, adrenal gland failure, hyperchloraemic acidosis, and hepatic cirrhosis. Marked hepatic or renal impairment. Not to be used for long-term treatment of angle-closure glaucoma.
Special Precautions
Patient w/ pulmonary obstruction or emphysema, prediabetes or DM. Pregnancy and lactation.
Adverse Reactions
Paraesthesia, hearing dysfunction or tinnitus, fatigue, malaise, loss of appetite, taste alteration, GI disturbances (e.g. nausea, vomiting, diarrhoea), polyuria, drowsiness, confusion, metabolic acidosis, electrolyte imbalance, transient myopia, urticaria, melaena, haematuria, glycosuria, hepatic insufficiency, flaccid paralysis, photosensitivity, convulsions. Rarely, crystalluria and renal calculi. Potentially Fatal: Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anaemia, and other blood dyscrasias.
Monitor CBC, platelet count and serum electrolytes periodically.
Drug Interactions
Concomitant use w/ high-dose aspirin may result to anorexia, tachypnoea, lethargy, coma and death. Concomitant use w/ steroids may result to hypokalaemia.
Action
Description: Methazolamide inhibits carbonic anhydrase resulting to decreased secretion of aqueous humour, thus decreasing intraocular pressure. Onset: 2-4 hr. Duration: 10-18 hr. Pharmacokinetics: Absorption: Well absorbed from the GI tract. Time to peak plasma concentration: 1-2 hr. Distribution: Distributed throughout the body including the plasma, CSF, aqueous humour of eye, RBC, bile and extra-cellular fluid. Volume of distribution: 17-23 L. Plasma protein binding: Approx 55%. Metabolism: Partially metabolised hepatically. Excretion: Via urine (approx 15-30%). Elimination half-life: Approx 14 hr.
Chemical Structure
Methazolamide Source: National Center for Biotechnology Information. PubChem Database. Methazolamide, CID=4100, https://pubchem.ncbi.nlm.nih.gov/compound/Methazolamide (accessed on Jan. 22, 2020)
Anon. Methazolamide. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 03/10/2014.Buckingham R (ed). Methazolamide. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 03/10/2014.McEvoy GK, Snow EK, Miller J et al (eds). Methazolamide (EENT). AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 03/10/2014.Methazolamide Tablet (Effcon Laboratories, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 03/10/2014.Wickersham RM. Methazolamide. Facts and Comparisons [online]. St. Louis, MO. Wolters Kluwer Clinical Drug Information, Inc. https://www.wolterskluwercdi.com/facts-comparisons-online/. Accessed 03/10/2014.
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