Macromate Drug Interactions

Antiepileptic Drugs: Concomitant administration of phenytoin or carbamazepine with topiramate resulted in a clinically significant decrease in plasma concentrations of topiramate when compared to topiramate given alone. A dosage adjustment may be needed.
Concomitant administration of valproic acid and topiramate has been associated with hypothermia and hyperammonemia with and without encephalopathy.
CNS Depressants: Concomitant administration of topiramate and alcohol or other CNS Depressant drugs has not been evaluated in clinical studies. Because of the potential of topiramate to cause CNS depression, as well as other cognitive and/or neuropsychiatric adverse reactions, topiramate should be used with extreme caution if used in combination with alcohol and other CNS depressants.
Oral Contraceptives: The possibility of decreased contraceptive efficacy and increased breakthrough bleeding may occur in patients taking combination oral contraceptive products with topiramate. Patients taking estrogen-containing contraceptives should be asked to report any change in their bleeding patterns. Contraceptive efficacy can be decreased even in the absence of breakthrough bleeding.
Lithium: An increase in systemic exposure of lithium following topiramate doses of up 600 mg/day can occur. Lithium levels should be monitored when co-administered with high-dose topiramate.
Other Carbonic Anhydrase Inhibitors: Concomitant use of topiramate, a carbonic anhydrase inhibitor, with any other carbonic anhydrase inhibitor (e.g., zonisamide or acetazolamide) may increase the severity of metabolic acidosis and may also increase the risk of kidney stone formation. Therefore, patients given topiramate concomitantly with another carbonic anhydrase inhibitor should be monitored particularly closely for the appearance or worsening of metabolic acidosis.
Hydrochlorothaizide (HCTZ): Topiramate Cmax and AUC increased when HCTZ was added to topiramate. The addition of HCTZ to topiramate may require a decrease in the topiramate dose.
Pioglitazone: When topiramate is added to pioglitazone therapy or pioglitazone is added to topiramate therapy, careful attention should be given to the routine monitoring of patients for adequate control of their diabetic disease state.