Answer
In the BNF appendix 1 Microgynon is not listed and there is no guidance to where to look. You are expected to look under ‘contraceptives, oral’. This will then direct you to Oestrogens and Progestogens. Both are listed separately. Under Oestrogens, carbamazepine doesn’t have a separate entry but antiepileptics do and, in this section, carbamazepine is shown with a black dot where it states that metabolism of oestrogen (or progestogen) is accelerated which you are then guided to a separate section of the BNF to show what is recommended if the drugs are given together. Not as straightforward as you may have hoped. In Appendix 1 carbamazepine is listed and oestrogens and progestogens are shown in the alphabetical list. So it sometimes depends on where you start your search.