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This work describes oral contraceptives (OCs) in current use and examines their risks. OC pills are composed of synthetic estrogens, usually either ethinyl estradiol or mestranol, and progestins. Either estrogens or progestins can be used alone, but combinations permit smaller doses to be used. Combined pills are available in monophasic, biphasic, or triphasic formulations. Different modalities of administration are also available for progestin-only pills. The "morning after" pill containing high doses of steroids to be taken within 72 hours of unprotected intercourse can contain either estrogen or progestin alone or combined. The mechanisms of action of OCs vary according to the type of pill. Classic combined OCs inhibit ovulation, render the cervical mucus inhospitable to sperm, and cause endometrial atrophy which hinders nidation. Low-dose pills have various effects but in general depend on changes in the cervical mucus for their contraceptive effect. Pregnancy may result from forgetting pills or using them incorrectly, or in the case of low-dose pills may occur even if they are used correctly. Some drugs can lower the concentrations of the OC hormones at the level of the receptors by hindering their intestinal absorption or by increasing the metabolic power of the liver. Considerable individual variability limits the incidence of pill failure due to drug interactions, but OC use should be avoided if rifampicine or certain other drugs are used. Among undesirable effects of OCs on endocrine glands and reproductive function are the adaptation syndrome characterized by symptoms similar to those of early pregnancy and reversible in most but not all women; galactorrhea resulting from diminished levels of "prolactin inhibiting factor"; and virilizing effects such as alopecia, hirsutism, and acne usually occurring during use of high-dose formulations. Pills should be carefully adapted to the hormonal profile of the user to avoid these side effects. OCs very rarely entail longterm infertility. OCs in current use do not appear to be teratogenic but it is advisable to wait 2 months after termination of use before becoming pregnant. Lactation is a contraindication to OC use. Combined OCs frequently cause problems in glucose tolerance of variable significance. Low-dose progestins do not seem to affect lipid metabolism, but low and normal dose combined pills may provoke increases in the levels of cholesterol and triglycerides. OCs are implicated in vascular accidents of various kinds, but low-dose pills are better tolerated. Cardiovascular risks are increased by age, smoking, use of alcohol, and excess fat in the diet. Hepatobiliary complications may occur during pill use. The carcinogenic role of OCx remains controversial, although growth of preexisting breast cancers is accelerated with pill use. The multifactorial etiologies of cardiovascular ailments, atherosclerosis, and cancerous tumors make the role of OCs difficult to assess. OCs can interact with various drugs, heightening the undesirable effects of each. Research on hormonal methods of contraception is currently directed toward achieving a better tolerance and administration of both male and female methods.
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PMID:[Oral contraception: failures and risks]. 1228 May 90