GROUP 1: Microgynon 30® for 21 days, Followed by Microgynon 30® for 21 days plus Evotaz® for 14 days, Followed by Evotaz® for 14 days GROUP 2: Evotaz® for 14 days followed by 7 days wash-out, Followed by Microgynon 30® for 21 days plus Evotaz® for 14 days, Followed by Microgynon 30® for 14 days (participants may chose to complete a 21 day pack). The total duration of the study is 57 days (+screening and follow up visits) and patients will have 3 intensive pharmacokinetic days on days 14, 35 and 56.