Actions and Spectrum:
Mechanism of Action:
- Inhibition of Ovulation: etonogestrel suppresses the secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus. As a result, the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland is reduced. LH and FSH are essential for the maturation and release of eggs (ovulation) from the ovaries. By inhibiting this process, etonogestrel prevents the release of eggs, reducing the likelihood of fertilization.
- Changes in Cervical Mucus: etonogestrel thickens the cervical mucus, making it more dense and less porous by sperm. This hinders the sperm’s ability to reach the egg in the fallopian tubes, reducing the chance of fertilization.
- Endometrial Changes: etonogestrel modifies the lining of the uterus (endometrium). It makes the endometrium less receptive to the implantation of a fertilized egg, should fertilization occur. This effect acts as an additional mechanism of contraception, preventing a fertilized egg from embedding and growing in the uterine lining.
Spectrum of Activity:
etonogestrel is a highly effective form of contraception and provides long-term protection. The spectrum of activity includes:
- Prevention of Pregnancy: etonogestrel is primarily used as a contraceptive to prevent pregnancy. Its ability to inhibit ovulation, alter cervical mucus, and change the endometrial lining collectively makes it highly effective in preventing pregnancy.
- Long-Acting Contraception: The contraceptive implant is one of the most reliable, reversible methods. Depending on the specific product, it can provide effective contraception for up to three to five years.
Convenience and Compliance: Once the implant is inserted under the skin, it does not require daily attention, which can be advantageous for people who may have difficulties with daily pill usage or other short-acting contraceptive methods.
