This updated Medicines Q&A provides advice on a suitable oral contraceptive that can be used in a woman using an enzyme-inducing anti-epileptic or anti-tubercle drug.
Suitable oral contraception for a patient taking an enzyme-inducing drug such as carbamazepine or phenytoin, is a combination of two COCs that contain the same progestogen and give a combined total of at least 50 micrograms of ethinylestradiol. The tricycling regimen is recommended, taking three or four cycles without a pill-free interval, then a shorter four-day pill-free break. These recommendations do not apply to very potent enzyme inducers such as rifampicin and rifabutin.
The use of a COC in this way is unlicensed. Some sources suggest using additional non-hormonal methods. The preferred method of contraception would be an IUD or injectable such as depot (MPA and can be used as the method of contraception for women taking very potent enzyme inducers such as rifampicin. Drugs which induce hepatic enzymes are unlikely to affect the pharmacokinetics of DMPA.
The link to the document can be found here