Topiramateinteractions

Oral contraceptives: Decreased contraceptive efficacy and increased breakthrough bleeding, especially at doses greater than 200 mg per day Monitor lithium levels if lithium is used with high-dose topiramate extended-release capsules

7.1 Alcohol

Alcohol use is contraindicated within 6 hours prior to and 6 hours after topiramate extended-release capsules administration.

7.2 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. Examine blood ammonia levels in patients in whom the onset of hypothermia has been reported.

7.3 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. Patients should be monitored for the appearance or worsening of metabolic acidosis when topiramate extended-release capsules is given concomitantly with another carbonic anhydrase inhibitor.

7.4 CNS Depressants

Concomitant administration of topiramate with other CNS depressant drugs or alcohol 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 extended-release capsules should be used with extreme caution if used in combination with alcohol and other CNS depressants.

7.5 Oral Contraceptives

The possibility of decreased contraceptive efficacy and increased breakthrough bleeding may occur in patients taking combination oral contraceptive products with topiramate extended-release capsules. 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.

7.6 Hydrochlorothiazide (HCTZ)

Topiramate C max and AUC increased when HCTZ was added to immediate-release topiramate. The clinical significance of this change is unknown. The addition of HCTZ to topiramate extended-release capsules may require a decrease in the topiramate extended-release capsules dose. 7.7 Pioglitazone A decrease in the exposure of pioglitazone and its active metabolites were noted with the concurrent use of pioglitazone and immediate-release topiramate in a clinical trial. The clinical relevance of these observations is unknown; however, when topiramate extended-release capsules is added to pioglitazone therapy or pioglitazone is added to topiramate extended-release capsules therapy, careful attention should be given to the routine monitoring of patients for adequate control of their diabetic disease state.

7.8 Lithium

An increase in systemic exposure of lithium following topiramate doses of up to 600 mg/day can occur. Lithium levels should be monitored when co-administered with high-dose topiramate extended-release capsules.

7.9 Amitriptyline

Some patients may experience a large increase in amitriptyline concentration in the presence of topiramate extended-release capsules and any adjustments in amitriptyline dose should be made according to the patients’ clinical response and not on the basis of plasma levels.