Contraceptive Action

Only one implantable contraceptive preparation is available at present. Norgestrel, also utilized as the progestin component of some oral contraceptive preparations, is an effective suppressant of ovulation when it is released from subcutaneous implants. Intramuscular injection of large doses of medroxyprogesterone also provides contraceptive action of long duration. 

As the LNG-IUD has a local contraceptive action progestogenic interactions are less likely to occur. The efficacy of the contraceptive patch may be reduced by enzyme-inducing drugs [3, 11, 19]. 

Oral contraceptives are widely used worldwide and have had a revolutionary impact by providing a convenient, affordable, and reliable means of contraception. Myriad agents with substantially different components, doses, and side effects provide real therapeutic options. In addition to contraceptive actions, these agents have substantial health benefits. 

An intrauterine device (progestasest) that releases low amounts of progesterone locally is available for insertion on a yearly basis. Its effectiveness is considered to be 97-98% contraceptive action probably is due to local effects on the endometrium. Another intrauterine device (MIRENA) releases levonorgestrel for up to 5 years. It again is thought to act primarily by local effects. 

Endocervical mechanisms of fertility control are characteristic of the luteal phase— the safe period —of the menstrual cycle and are also of paramount importance in the combination pill regimens [120] and in the various minipill regimens [137, 183, 184] and in the precoital use of progestagens [168]. It must be remembered, however, that the changes induced in endocervical mechanisms by progestagens are not yet fully understood and there is no doubt that gross examination of mucin is not a reliable guide to contraceptive action [145]. 

Coumarins and furocoumarins - These compounds increase human and animal sensitivity to ultraviolet light and are used to treat vitiligo. Some have phyto-estrogenic action. When eaten by sheep and other animals, plants containing coumarins and furocoumarins have contraceptive action. Ingestion can cause fetal death in early pregnancy as well. 

The mechanism of contraceptive action is believed to be that the presence of an extraneous quantity of these hormones, particularly progestin, mimics the hormone condition of pregnancy. Hence, the body mistakes itself as being pregnant and suppresses ovulation. Recall that progesterone is secreted in a large quantity by... 

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