Increased clearance of sex hormones w/ phenytoin, barbiturates, primidone, carbamazepine, rifampicin, bosentan & HIV-medication (eg, ritonavir, nevirapine) & possibly oxcarbazepine, topiramate, felbamate, griseofulvin & St. John's wort (
Hypericum perforatum)-containing products. Increased ciclosporin or decreased lamotrigine plasma & tissue conc.