Acetazolamide

Registered South African indications: 

• Acute primary and secondary glaucoma

Registered South African contraindications

• Hypersensitivity to the active ingredient or any of its excipients
• Hypersensitivity to sulphonamides
• Presence of sodium or potassium depletion
• Idiopathic renal hyperchloraemic acidosis
• Conditions such as Addison's disease and adrenal failure
• Marked hepatic or renal failure
• Chronic, non-congested closed-angle glaucoma
• First trimester of pregnancy

Contraindications registered in other jurisdictions

• Hypersensitivity to the active substance or to any of the excipients
• Hypersensitivity to sulphonamides
• Depressed sodium and/or potassium blood levels
• Marked kidney and liver disease or dysfunction
• Suprarenal gland failure
• Hyperchloremic acidosis
• Patients with hepatic cirrhosis due to increased risk of hepatic encephalopathy
• Long-term administration in patients with chronic non-congestive angle-closure glaucoma

• Second and third trimester of pregnancy (South African recommendations)
• Pregnancy (Recommendations in other jurisdictions) 
• Breastfeeding
• Elderly
• Prolonged use
• Pulmonary obstruction 
• Impaired alveolar ventilation
• May impair ability to drive or operate machinery

Forms avail. in SA and covered in this monograph: tab

South African registered indications and dosages

Acute primary and secondary glaucoma

• Oral (tab): Initial: 500mg; Maintenance: 250mg, 6-8hrly

Not established for use in children

Pregnancy

South African recommendations

• First trimester: Contraindicated
• The use of acetazolamide should be avoided in the first trimester of pregnancy
• Second and third trimester: Caution; no information available

Recommendations in other jurisdictions

• Caution; not recommended
• Acetazolamide has been reported to be teratogenic and embryotoxic in rats, mice, hamsters and rabbits at oral or parenteral doses in excess of ten times those recommended in human beings
• Although there is no evidence of these effects in human beings, there are no adequate and well-controlled studies in pregnant women
• Therefore acetazolamide tablets should not be used in pregnancy, especially during the first trimester

Breastfeeding

Recommendations below are applicable to South Africa and other jurisdictions

• Caution
• Acetazolamide has been detected in low levels in the milk of lactating who have taken acetazolamide tablets
• Although it is unlikely that this will lead to any harmful effects in the  infant, extreme caution should be exercised when acetazolamide tablets is administered to lactating women

Fertility

Recommendations below are applicable to South Africa and other jurisdictions

• No information available

Recommendations below are applicable to South Africa and other jurisdictions

• Marked renal failure: Contraindicated
  In patients with a past history of renal calculi, benefit should be balanced against the risk of precipitating further calculi

Recommendations below are applicable to South Africa and other jurisdictions

• Marked hepatic failure: Contraindicated
  Rarely, in patients with hepatic cirrhosis, it may cause disorientation

South African recommendations

• Caution; no information available

Recommendations in other jurisdictions

• Caution; no dose adjustment recommended
  Acetazolamide tablets should only be used with particular caution in elderly patients or those with potential obstruction in the urinary tract or with disorders rendering their electrolyte balance precarious or with liver dysfunction

Central Nervous System Disorders

• Paraesthesia
• Headache
• Dizziness
• Fatigue
• Irritability
• Depression
• Drowsiness 
• Confusion
• Flaccid paralysis
• Seizures

Gastrointestinal Disorders

• Nausea and vomiting 
• Diarrhoea
• Melaena

Hepatobiliary Disorders

• Fulminant hepatic necrosis
• Abnormal liver function
• Hepatitis
• Cholestatic jaundice

Genitourinary Disorders

• Polyuria
• Crystalluria
• Calculus formation
• Renal and ureteral colic
• Renal lesions
• Haematuria
• Glycosuria
• Renal failure

Endocrine and Metabolic Disorders

• Loss of appetite
• Reduced libido 
• Thirst
• Metabolic acidosis 
• Electrolyte imbalance

Skin and Subcutaneous Tissue Disorders

• Photosensitivity
• Rash
• Erythema multiforme
• Stevens-Johnson syndrome
• Toxic epidermal necrolysis
• Urticaria

Immune, Blood and Lymphatic System Disorders

• Anaphylaxis
• Agranulocytosis
• Thrombocytopenia
• Thrombocytic purpura
• Leukopenia
• Aplastic anaemia
• Bone marrow depression
• Pancytopenia
• Fever

Sensory Disorders

• Taste disturbance
• Myopia
• Impaired hearing
• Tinnitus

Others

• Flushing

• Folic acid antagonists
• Hypoglycaemic agents
• Oral anticoagulants
• Cardiac glycosides 
• Hypertensive agents
• Aspirin
• Anticonvulsants
• Phenytoin
• Carbonic anhydrase inhibitors
• Amphetamines 
• Quinidine
• Ciclosporin
• Methenamine
• Lithium
• Sodium bicarbonate

• Full blood count
• Electrolytes

Acetazolamide is an inhibitor of carbonic anhydrase. By inhibiting the reaction catalysed by carbonic anhydrase in the renal tubules, acetazolamide increases the excretion of bicarbonates and of cations, chiefly sodium and potassium, and so promotes an alkaline diuresis. By inhibiting carbonic anhydrase in the eye, acetazolamide reduces the rate of aqueous humour formation and thus decreases intra­ocular pressure. A mild degree of metabolic acidosis persists for as long as the medicine is given.

Tablet 250mg

• Azomid (Adcock) 
• Diamox (Pharmafrica) (Discontinued: 27/11/2020)