Hormonal contraceptives

Hormonal contraceptives

Hormonal contraceptives inhibit ovulation. Contraceptives typically contain a combination of hormones. For example, ethinyl estradiol may be combined with desogestrel, drospirenone, levonorgestrel, norethindrone, norgestimate, or norgestrel. Also, mestranol may be combined with norethindrone. Ethinyl estradiol or ethynodiol diacetate may also be used alone as a contraceptive.

Pharmacokinetics

Hormonal contraceptives are absorbed from the GI tract and are widely distributed. They’re metabolized in the kidneys and excreted in urine and feces.

Patch power

Some forms of hormonal contraceptives are available in a transdermal patch form. These contraceptives are absorbed through the skin but have the same distribution, metabolism, and excretion as orally administered contraceptives.

Pharmacodynamics

The primary mechanism of action of combination hormonal contraceptives (estrogen and progestin) is the suppression of gonadotropins, which inhibits ovulation. Estrogen suppresses secretion of follicle-stimulating hormone, which blocks follicular development and ovulation. Progestin suppresses the secretion of luteinizing hormone, which prevents ovulation, even if the follicle develops. Progestin also thickens the cervical mucus; this interferes with sperm migration and causes endometrial changes that prevent implantation of a fertilized ovum.

Pharmacotherapeutics

The primary purpose for taking hormonal contraceptives is the prevention of pregnancy in women. The combination of ethinyl estradiol and norgestimate is also used to treat moderate acne in females younger than age 15.

Drug interactions

Hormonal contraceptives can interact with other medications in various ways:

• Antibiotics, oxcarbazepine, phenobarbital, phenytoin, topiramate, and modafinil may decrease the effectiveness of oral contraceptives. A patient taking these drugs with a hormonal contraceptive needs to use a barrier contraceptive.
• Atorvastatin may increase serum estrogen levels.
• Cyclosporin and theophylline have an increased risk of toxicity when taken with hormonal contraceptives.
• Prednisone increases the therapeutic and possibly toxic effects of hormonal contraceptives. 
• Several herbal medications can affect serum levels of hormonal contraceptives.

Warning!

Adverse reactions to hormonal contraceptives

Potentially serious adverse reactions to hormonal contraceptives include arterial thrombosis, thrombophlebitis, pulmonary embolism, myocardial infarction, cerebral hemorrhage or thrombosis, hypertension, gallbladder disease, and hepatic adenomas.

Other adverse reactions include:

• acne
• bleeding or spotting between menstrual periods
• bloating
• breast tenderness or enlargement
• changes in libido
• diarrhea
• difficulty wearing contact lenses
• unusual hair growth
• weight fluctuations
• upset stomach
• vomiting.