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Acetazolam

Acetazolam - General Information

One of the carbonic anhydrase inhibitors that is sometimes effective against absence seizures. It is sometimes useful also as an adjunct in the treatment of tonic-clonic, myoclonic, and atonic seizures, particularly in women whose seizures occur or are exacerbated at specific times in the menstrual cycle. However, its usefulness is transient often because of rapid development of tolerance. Its antiepileptic effect may be due to its inhibitory effect on brain carbonic anhydrase, which leads to an increased transneuronal chloride gradient, increased chloride current, and increased inhibition. (From Smith and Reynard, Textbook of Pharmacology, 1991, p337)

 

Pharmacology of Acetazolam

Acetazolam is a potent carbonic anhydrase inhibitor, effective in the control of fluid secretion, in the treatment of certain convulsive disorders and in the promotion of diuresis in instances of abnormal fluid retention. Acetazolam is not a mercurial diuretic. Rather, it is a nonbacteriostatic sulfonamide possessing a chemical structure and pharmacological activity distinctly different from the bacteriostatic sulfonamides.

 

Acetazolam for patients

Adverse reactions common to all sulfonamide derivatives may occur: anaphylaxis, fever, rash (including erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), crystalluria, renal calculus, bone marrow depression, thrombocytopenic purpura, hemolytic anemia, leukopenia, pancytopenia, and agranulocytosis. Caution is advised for early detection of such reactions and the drug should be discontinued and appropriate therapy instituted.

In patients with pulmonary obstruction or emphysema where alveolar ventilation may be impaired, DIAMOX, which may precipitate or aggravate acidosis, should be used with caution.

Gradual ascent is desirable to try to avoid acute mountain sickness. If rapid ascent is undertaken and DIAMOX is used, it should be noted that such use does not obviate the need for prompt descent if severe forms of high altitude sickness occur, ie, high altitude pulmonary edema (HAPE) or high altitude cerebral edema.

Caution is advised for patients receiving concomitant high-dose aspirin and DIAMOX, as anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death have been reported.

Both increases and decreases in blood glucose levels have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus.

Acetazolamide treatment may cause electrolyte imbalances, including hyponatremia and hypokalemia, as well as metabolic acidosis. Therefore, periodic monitoring of serum electrolytes is recommended. Particular caution is recommended in patients with conditions that are associated with, or predispose a patient to, electrolyte and acid/base imbalances, such as patients with impaired renal function (including elderly patients), patients with diabetes mellitus, and patients with impaired alveolar ventilation.

Some adverse reactions to acetazolamide, such as drowsiness, fatigue, and myopia, may impair the ability to drive and operate machinery.

 

Acetazolam Interactions

DIAMOX®. modifies phenytoin metabolism with increased serum levels of phenytoin. This may increase or enhance the occurrence of osteomalacia in some patients receiving chronic phenytoin therapy. Caution is advised in patients receiving chronic concomitant therapy.

By decreasing the gastrointestinal absorption of primidone, DIAMOX may decrease serum concentrations of primidone and its metabolites, with a consequent possible decrease in anticonvulsant effect. Caution is advised when beginning, discontinuing, or changing the dose of DIAMOX in patients receiving primidone.

Because of possible additive effects with other carbonic anhydrase inhibitors, concomitant use is not advisable.

Acetazolamide may increase the effects of other folic acid antagonists.

Acetazolamide may increase or decrease blood glucose levels. Consideration should be taken in patients being treated with antidiabetic agents.

Acetazolamide decreases urinary excretion of amphetamine and may enhance the magnitude and duration of their effect.

Acetazolamide reduces urinary excretion of quinidine and may enhance its effect.

Acetazolamide may prevent the urinary antiseptic effect of methenamine.

Acetazolamide increases lithium excretion and the lithium may be decreased.

Acetazolamide and sodium bicarbonate used concurrently increases the risk of renal calculus formation.

Acetazolamide may elevate cyclosporine levels.

 

Acetazolam Contraindications

Hypersensitivity to acetazolamide or any excipients in the formulation. Since acetazolamide is a sulfonamide derivative, cross sensitivity between acetazolamide, sulfonamides and other sulfonamide derivatives is possible.

DIAMOX therapy is contraindicated in situations in which sodium and/or potassium blood serum levels are depressed, in cases of marked kidney and liver disease or dysfunction, in suprarenal gland failure, and in hyperchloremic acidosis. It is contraindicated in patients with cirrhosis because of the risk of development of hepatic encephalopathy.

Long-term administration of DIAMOX is contraindicated in patients with chronic noncongestive angle-closure glaucoma since it may permit organic closure of the angle to occur while the worsening glaucoma is masked by lowered intraocular pressure.

 

Additional information about Acetazolam

Acetazolam Indication: For adjunctive treatment of: edema due to congestive heart failure; drug-induced edema; centrencephalic epilepsies; chronic simple (open-angle) glaucoma
Mechanism Of Action: The anticonvulsant activity of Acetazolam may depend on a direct inhibition of carbonic anhydrase in the CNS, which decreases carbon dioxide tension in the pulmonary alveoli, thus increasing arterial oxygen tension. The diuretic effect depends on the inhibition of carbonic anhydrase, causing a reduction in the availability of hydrogen ions for active transport in the renal tubule lumen. This leads to alkaline urine and an increase in the excretion of bicarbonate, sodium, potassium, and water.
Drug Interactions: Aspirin The salicylate at high dose increases the effect of the carbonic anhydrase inhibitors
Salicyclic acid The salicylate at high dose increases the effect of the carbonic anhydrase inhibitors
Cyclosporine Acetazolam increases the effect of toxicity of cyclosporine
Memantine Possible increased levels of memantine
Bismuth Subsalicylate The salicylate at high dose increases the effect of the carbonic anhydrase inhibitors
Food Interactions: Take with food; at least 6 hours before bedtime.
Drink plenty of liquids.
Generic Name: Acetazolamide
Synonyms: Acetamidothiadiazolesulfonamide; Acetazolamid; Acetazolamide Sodium; Acetazolamine; Acetazoleamide; Acetozalamide; Carbonic Anhydrase Inhibitor 6063
Drug Category: Diuretics; Anticonvulsants; Carbonic Anhydrase Inhibitors
Drug Type: Small Molecule; Approved
Other Brand Names containing Acetazolamide: Acetamox; Acetazolam; Ak-Zol; Apo-Acetazolamide; Atenezol; Cidamex; Dazamide; Defiltran; Dehydratin; Diacarb; Diakarb; Diamox; Diamox Sequels; Didoc; Diluran; Diuramid; Diureticum-Holzinger; Diuriwas; Diutazol; Donmox; Duiramid; Edemox; Eumicton; Fonurit; Glaupax; Glupax; Natrionex; Nephramid; Nephramide; Phonurit; Sk-Acetazolamide; Storzolamide; Vetamox;
Absorption: Not Available
Toxicity (Overdose): Not Available
Protein Binding: 98%
Biotransformation: Not Available
Half Life: 3 to 9 hours
Dosage Forms of Acetazolam: Tablet Oral
Chemical IUPAC Name: N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)acetamide
Chemical Formula: C4H6N4O3S2
Acetazolamide on Wikipedia: http://en.wikipedia.org/wiki/Acetazolamide
Organisms Affected: Humans and other mammals