Rufinamide

Patients on valproate should begin at a BANZEL dose lower than 10 mg/kg per day (pediatric patients) or 400 mg per day (adults) ( 7.2 ) Hormonal contraceptives may be less effective with BANZEL; use additional non-hormonal forms of contraception ( 7.3 )

7.1 Effects of BANZEL on other AEDs Population pharmacokinetic analysis of average concentration at steady state of carbamazepine, lamotrigine, phenobarbital, phenytoin, topiramate, and valproate showed that typical rufinamide C avss levels had little effect on the pharmacokinetics of other AEDs. Any effects, when they occur, have been more marked in the pediatric population. Table 6 summarizes the drug-drug interactions of BANZEL with other AEDs.

Table 6: Summary of drug-drug interactions of BANZEL with other antiepileptic drugs AED Co-administered Influence of Rufinamide on AED concentration a) Influence of AED on Rufinamide concentration Carbamazepine Decrease by 7 to 13% b) Decrease by 19 to 26% Dependent on dose of carbamazepine Lamotrigine Decrease by 7 to 13% b) No Effect Phenobarbital Increase by 8 to 13% b) Decrease by 25 to 46% c) ’ d) Independent of dose or concentration of phenobarbital Phenytoin Increase by 7 to 21% b) Decrease by 25 to 46% c) ’ d) Independent of dose or concentration of phenytoin Topiramate No Effect No Effect Valproate No Effect Increase by <16 to 70% c) Dependent on concentration of valproate Primidone Not Investigated Decrease by 25 to 46% c) ’ d) Independent of dose or concentration of primidone Benzodiazepines e) Not Investigated No Effect a) Predictions are based on BANZEL concentrations at the maximum recommended dose of BANZEL. b) Maximum changes predicted to be in pediatric patients and in adult patients who achieve significantly higher levels of BANZEL, as the effect of rufinamide on these AEDs is concentration-dependent. c) Larger effects in pediatric patients at high doses/concentrations of AEDs. d) Phenobarbital, primidone and phenytoin were treated as a single covariate (phenobarbital-type inducers) to examine the effect of these agents on BANZEL clearance. e) All compounds of the benzodiazepine class were pooled to examine for ‘class effect’ on BANZEL clearance. Phenytoin: The decrease in clearance of phenytoin estimated at typical levels of rufinamide (C avss 15 μg/mL) is predicted to increase plasma levels of phenytoin by 7 to 21%. As phenytoin is known to have non-linear pharmacokinetics (clearance becomes saturated at higher doses), it is possible that exposure will be greater than the model prediction.

7.2 Effects of Other AEDs on BANZEL Potent cytochrome P450 enzyme inducers, such as carbamazepine, phenytoin, primidone, and phenobarbital, appear to increase the clearance of BANZEL (see Table 6). Given that the majority of clearance of BANZEL is via a non-CYP-dependent route, the observed decreases in blood levels seen with carbamazepine, phenytoin, phenobarbital, and primidone are unlikely to be entirely attributable to induction of a P450 enzyme. Other factors explaining this interaction are not understood. Any effects, where they occurred, were likely to be more marked in the pediatric population.

Valproate Patients stabilized on BANZEL before being prescribed valproate should begin valproate therapy at a low dose, and titrate to a clinically effective dose. Similarly, patients on valproate should begin at a BANZEL dose lower than 10 mg/kg per day (pediatric patients) or 400 mg per day (adults) [ see Dosage and Administration ( 2.5 ) , Clinical Pharmacology ( 12.3 ) ] .

7.3 Effects of BANZEL on Hormonal Contraceptives Female patients of childbearing age should be warned that the concurrent use of BANZEL with hormonal contraceptives may render this method of contraception less effective. Additional non-hormonal forms of contraception are recommended when using BANZEL [ see Use in Specific Populations ( 8.3 ), Clinical Pharmacology ( 12.3 ) and Patient Counseling Information ( 17 ) ] .

8.1 P regnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to AEDs, such as BANZEL, during pregnancy. Encourage women who are taking BANZEL during pregnancy to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry by calling 1-888-233-2334 or visiting http://www.aedpregnancyregistry.org Risk Summary There are no adequate data on the developmental risks associated with use of BANZEL in pregnant women. In animal reproduction studies, oral administration of rufinamide resulted in developmental toxicity in pregnant rats and rabbits at clinically relevant doses [see Data ] . In the U.S.

general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown. Data Animal data Oral administration of rufinamide (0, 20, 100, or 300 mg/kg/day) to pregnant rats throughout organogenesis resulted in decreased fetal weight and increased incidence of fetal skeletal abnormalities at 100 and 300 mg/kg/day, which were associated with maternal toxicity.

The maternal plasma exposure (AUC) at the no-adverse effect dose (20 mg/kg/day) for developmental toxicity was less than that in humans at the maximum recommended human dose (MRHD) of 3200 mg/day. Oral administration of rufinamide (0, 30, 200, or 1000 mg/kg/day) to pregnant rabbits throughout organogenesis resulted in embryofetal death, decreased fetal body weight, and increased incidence of fetal visceral and skeletal abnormalities at doses of 200 and 1000 mg/kg/day. The high dose (1000 mg/kg/day) was associated with abortion. Plasma exposure (AUC) at the no-adverse effect dose (30 mg/kg/day) was less than that in humans at the MRHD.

When rufinamide was orally administered (0, 5, 30, or 150 mg/kg/day) to pregnant rats throughout pregnancy and lactation, decreased offspring growth and survival were observed at all doses tested. A no-effect dose for adverse effects on pre- and postnatal development was not established. At the lowest dose tested (5 mg/kg/day), plasma exposure (AUC) was less than that in humans at the MRHD.