Gastrointestinal disease and oral contraception

Area of Science:

• Pharmacology
• Reproductive Health
• Gastroenterology

Background:

• Oral contraceptive steroids are crucial for family planning, with a trend towards lower doses.
• Reduced bioavailability of lower-dose oral contraceptives may impact contraceptive efficacy.
• Ethinyl estradiol undergoes enterohepatic circulation, but common progestogens do not.

Purpose of the Study:

• To evaluate the impact of factors affecting oral contraceptive steroid bioavailability on contraceptive protection.
• To assess the role of enterohepatic circulation and gastrointestinal absorption in oral contraceptive efficacy.

Main Methods:

• Review of existing human subject data regarding the effects of antibiotics, antacids, and gastrointestinal conditions on oral contraceptive efficacy.
• Analysis of the absorption pathways of oral contraceptive steroids in the small bowel.

Main Results:

• No convincing evidence currently shows that antibiotics or antacids reduce contraceptive efficacy by disrupting enterohepatic circulation.
• Oral contraceptive steroids are primarily absorbed in the small intestine, making absorptive capacity critical.
• Conditions causing enhanced gastrointestinal passage or impaired absorption may lead to contraceptive failure.

Conclusions:

• Contraceptive efficacy is directly linked to the absorptive capacity of the small bowel.
• Patients with inflammatory bowel disease, diarrhea, ileostomy, or jejunoileal bypass may be at higher risk of contraceptive failure due to altered drug absorption.
• Further research may be needed to fully understand the impact of gastrointestinal factors on modern, lower-dose oral contraceptives.