[Long acting hormonal contraception].
Long-acting hormonal contraception has been widely accepted in different cultures, where the use of injectables and implants is preferred over other methods of fertility control. The administration of synthetic progestogens in combination with estrogens as injectables suppresses ovulation, allowing the control of the endometrial bleeding too. The use of injectables containing only progesterone constitutes a 2 to 6 months contraceptive method with high effectiveness and easy administration, although its major disadvantage is the alteration of the endometrial bleeding pattern, which is the most common cause of discontinuation. The group of long-acting injectables includes the development of microencapsulated steroids, whose structure gives them the property of maintaining controlled liberation of the drug. Recently subdermal contraceptive implants (Norplant) have appeared, based on the subcutaneous sustained liberation 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 main secondary effect is bleeding pattern disturbance during the menstrual cycle. The Capronor constitutes a new system of contraceptive implant which is different from Norplant, where the capsules containing levonorgestrel are of unbiodegradable material, and Capronor is formed by a biodegradable polimerus. Finally, among the contraceptive methods that have been developed to date there are the vaginal rings; these rings are silastic made and allow a continuous release of levonorgestrel or progestins.