Pharmacokinetic evaluation of desogestrel as a female contraceptive.

INTRODUCTION: Desogestrel (DSG) is a third-generation 19-nortestosterone derivative progestogen. It is contained in many oral contraceptive preparations, both combined (COCs) to ethinyl-estradiol (EE) or alone in a progestin-only pill (POP). Its principal metabolite (etonogestrel, ETN) is the only progestin used for intravaginal combined contraception and one of the most used for subdermal hormonal contraception. AREAS COVERED: This is a review of the available data on the pharmacokinetics of DSG and ETN in hormonal contraception. The material included was searched and obtained via Medline, PubMed, and EMBASE up to July 2013 using the search terms 'pharmacokinetics, metabolism' in combination with 'desogestrel, etonogestrel, and progestins.' EXPERT OPINION: DSG and its metabolite ETN are very suitable molecules for use in hormonal contraception. For the oral use the molecule used is DSG, while for parenteral routes (intravaginal, subdermal) its metabolite ETN is the compound of choice. In both cases (oral and parenteral) the active molecule in the organism is the latter (ETN), due to the rapid in vivo metabolism of oral DSG. The contraceptive efficacy and tolerability of all the formulations present on the market (mono/multiphasic EE/DSG COCs, DSG POP, EE/ETN vaginal ring, ETN implant) are reassuring, permitting a long-term use. The estrogenic component increases the contraindications, forcing the prescription to the safer only-progestin preparations, DSG POP or ETN implant.