Answer
Rifampicin, carbamazepine or phenytoin may induce hepatic cytochrome-P450-3A4, increasing progesterone elimination and thereby decreasing the bioavailability of progesterone from Cyclogest pessaries.
Sources for this answer
- Cyclogest 200mgL.D. Collins & Co. Ltd. · emc · SmPC §4.5 Interaction with other medicinal products · Version 14Document updated
Sources checked