[Long-acting hormonal contraception]

Longacting hormonal contraception has been widely accepted among different cultures where the use of injectables and implants is preferred over other methods of fertility control. Administration of synthetic progestogens in combination with estrogens as injectables suppresses ovulation allowing for the control of endometrial bleeding as well. Use of injectables containing progesterone only constitutes a 2-6 month contraceptive method with high effectiveness and easy administration; its major disadvantage is the alteration of the endometrial bleeding pattern which is the most common cause for discontinuation. The group of longacting injectables includes the development of microencapsulated steroids whose structure gives them the property of maintaining controlled delivery of the drug. Recently subdermal contraceptive implants (Norplant) have appeared and these are based on the subcutaneous sustained delivery of levonorgestrel. The daily drug dose is enough to inhibit ovulation in the initial months of use and modifies the cervical mucus in the subsequent months. Norplant has been shown to be efficient in preventing pregnancy but its major secondary effect is bleeding pattern disturbance during the menstrual cycle. The Capronor constitutes a new system of contraceptive implant which differs from Norplant; the 1st is a capsule containing levonorgestrel and is of nonbiodegradable material and the latter is formed by a biodegradable polimerus. Finally among the contraceptive methods which have been developed to date there are vaginal rings made of silastic which allow a continuous release of levonorgestrel or progestins. (authors modified) (summaries in SPA ENG)