Oral contraceptives, which are abbreviated as OCPs, also known as birth control pills, are medications taken by mouth for the purpose of birth control. Most oral contraceptives contain a combination of 2 types of hormones. One is estrogen and the other is progestin. Both of these hormones are naturally found in women’s bodies. There are many different types of estrogens and progestins, and different types of pills contain different combinations, but they all work similarly. Some pills contain only progestin, sometimes called the “mini-pill”.

Oral Contraceptives (OCs) once ingested, they inhibit the release of gonadotropin releasing hormone (GRH) by the hypothalamus, thus inhibiting the release of the pituitary hormones that stimulate ovulation. Oral Contraceptives also affect the lining of the uterus and cause the cervical mucus to thicken, making it impervious to sperm. If used consistently and correctly, oral contraceptives are an effective form of contraception. OCs may be started at any time in a woman's life up until menopause.

For most combination oral contraceptives, an active pill (estrogen plus progestin) is taken daily for 21 to 24 days. Then, an inactive (placebo) pill is taken daily for 4 to 7 days to allow for withdrawal bleeding. In some products, the placebo pill contains iron and folate (folic acid); in others, this pill is not truly inactive but contains 10 mcg of ethinyl estradiol. Combination Oral Contraceptives are also available as extended-cycle products or as continuous-use products. Most combination Oral Contraceptives contains 10 to 35 mcg of ethinyl estradiol. This dose is considered low. Low-dose OCs are usually preferred to high-dose OCs (50 mcg of estrogen) because low-dose OCs appear equally effective and have fewer adverse effects, except for a higher incidence of irregular vaginal bleeding during the first few months of use. Estradiol valerate may be used instead of ethinyl estradiol. The doses of estrogen and progestin are the same throughout the month in some combination OCs (monophasic pills); they change throughout the month in others (multiphasic pills).

If birth control pills are taken perfectly (100% of the time), the chance of pregnancy is 0.1%. However, in the real world, accounting for missed days of use, the chance of pregnancy is about 8% per year. Side effects of oral contraceptives vary depending on the pills’ hormone levels and types. Some include vaginal spotting and abnormal bleeding, breast tenderness, bloating, and nausea. Studies have shown that birth control pills do not cause major weight gain. Oral contraceptives may also have some beneficial effects other than birth control. They can help with irregular or heavy periods, painful periods or premenstrual syndromes, polycystic ovarian syndrome, acne, uterine fibroids, and endometriosis.

Some drugs can induce liver enzymes that accelerate transformation of OCs to less biologically active metabolites. Women who take these drugs should not be given OCs concurrently unless other contraceptive methods are unavailable or unacceptable. These drugs include certain antiseizure drugs which are most commonly phenytoin, carbamazepine, barbiturates, primidone, topiramate, and oxcarbazepine, ritonavir-boosted protease inhibitors, rifampin, and rifabutin. Lamotrigine should not be used with OCs because OCs can decrease lamotrigine levels and affect seizure control.

Regards

Mary Wilson

Editorial office

Journal of Clinical Pharmacology and Toxicology

E-mail: pharmatoxicol@eclinicalsci.com