Types of Contraceptive
Hormonal Contraceptives; Anticonceptivos hormonales; Contraceptifs Hormonaux; Hormonale Kontrazeptiva
Hormonal contraceptives are currently only available for women although preparations for men are being evaluated. Oral hormonal contraceptives for women are divided into 2 main types: ‘combined’ (containing an oestrogen and a progestogen) and ‘progestogen-only’. Parenteral preparations have also been developed and include subcutaneous implants and depot intramuscular injections. Progestogen-releasing intra-uterine devices and a combined hormonal contraceptive vaginal ring are available. A combined hormonal transdermal patch has also been developed.
Parenteral progestogen-only contraceptives provide reliable suppression of ovulation by suppressing the necessary mid-cycle surge of luteinising hormone. However, the low doses in progestogen-only oral contraceptives do not suppress it reliably in all cycles. Contraceptive efficacy is instead achieved by thickening the cervical mucus so that it is not readily penetrated by sperm, and by preventing proliferation of the endometrium so that it remains unfavourable for implantation of any fertilised ova. Intra-uterine progestogen-only devices act similarly the physical presence of the system in the uterus may also contribute to overall contraceptive efficacy.
Oestrogens inhibit ovulation by suppressing the mid-cycle release of follicle-stimulating hormone. They act synergistically with progestogens in combined oral contraceptives to provide regular and consistent suppression of ovulation.
Oral preparations are also available for emergency contraception after unprotected coitus they prevent implantation of any fertilised ova.
This post has been viewed 3240 times.