By alkalinizing the urine, the urinary excretion of amphetamines is decreased, enhancing the magnitude and duration of effects. Avoid coadministration, especially in overdose situations.
Coadministration may cause severe mixed acidosis in patients with respiratory disorders. Use with caution. If acidosis occurs, discontinue one or both drugs.
Carbonic anhydrase inhibitors (eg, methazolamide)
Because of additive effects, avoid other carbonic anhydrase inhibitors.
Cyclosporine concentrations may be elevated, increasing the pharmacologic effect and adverse reactions. Monitor cyclosporine concentrations and adjust the cyclosporine dose as needed.
Folic acid antagonists
The pharmacologic effects of folic acid antagonists may be increased. Use with caution.
Phenytoin serum concentrations may be elevated, increasing the pharmacologic effects and risk of toxicity. Use with caution. Monitor phenytoin concentrations and the patient’s response. Adjust the phenytoin dose as needed.
Lithium serum concentrations may be reduced, decreasing the therapeutic response. Monitor lithium concentrations and the patient’s response. If an interaction is suspected, adjust the lithium dose as needed.
Acetazolamide may interfere with the antibacterial effect of methenamine. Avoid coadministration. Consider use of a urinary antimicrobial agent not affected by urinary alkalinization.
Plasma concentrations of primidone and its metabolites may be reduced, decreasing the anticonvulsant effect. Use with caution when starting, stopping, or changing the dose of acetazolamide. If an interaction is suspected, consider use of an alternative anticonvulsant agent.
Quinidine serum levels may be increased. Because of urinary alkalinization, urinary excretion of quinidine is decreased, increasing the pharmacologic and toxic effects. Use with caution. Monitor quinidine concentrations and cardiac function when starting or stopping acetazolamide. Adjust the quinidine dose as needed.
May cause acetazolamide accumulation and toxicity, including CNS depression, and metabolic acidosis, coma, and death. Monitor salicylate concentrations, acid-base parameters, and CNS status. Adjust the acetazolamide dose as needed.
Coadministration increases the risk of renal calculus formation. Avoid coadministration.
Concomitant use of topiramate with acetazolamide may increase the risk of kidney stone formation. Avoid coadministration.