The combined oral contraceptive pill is a birth control method that includes a combination of an estrogen and a progestin.Combined oral contraceptive pills were developed to prevent ovulation by suppressing the release of gonadotropins. Combined hormonal contraceptives, including COCPs, inhibit follicular development and prevent ovulation as their primary mechanism of action.
Progestagen negative feedback decreases the pulse frequency of gonadotropin-releasing hormone (GnRH) release by the hypothalamus, which decreases the release of follicle-stimulating hormone (FSH) and greatly decreases the release of luteinizing hormone (LH) by the anterior pituitary. Decreased levels of FSH inhibit follicular development, preventing an increase in estradiol levels. Progestagen negative feedback and the lack of estrogen positive feedback on LH release prevent a mid-cycle LH surge. Inhibition of follicular development and the absence of a LH surge prevent ovulation.
Estrogen was originally included in oral contraceptives for better cycle control (to stabilize the endometrium and thereby reduce the incidence of breakthrough bleeding), but was also found to inhibit follicular development and help prevent ovulation. Estrogen negative feedback on the anterior pituitary greatly decreases the release of FSH, which inhibits follicular development and helps prevent ovulation.
Combined oral contraceptives may influence coagulation, increasing the risk of deep venous thrombosis (DVT) and pulmonary embolism, stroke and myocardial infarction. Combined oral contraceptives are generally accepted to be contraindicated in women with pre-existing cardiovascular disease, in women who have a familial tendency to form blood clots (such as familial factor V Leiden), women with severe obesity and/or hypercholesterolemia, and in smokers over age 40.And they are also contraindicated for women with Liver tumors, hepatic adenoma or severe cirrhosis of the liver, and for those with known or suspected breast cancer.
COC decrease the risk of ovarian cancer, endometrial cancer and colorectal cancer.
by
Akshaya Srikanth
Pharm.D Internee
Hyderabad, India
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