DRUG-DRUG INTERACTIONS
Interactions between ethinyl estradiol and other drugs have been reported in the literature.
- Interactions with Absorption. Diarrhea may increase gastrointestinal motility and reduce hormone absorption. Similarly, any drug which reduces gut transit time may reduce hormone concentrations in the blood.
- Interactions with Metabolism
Gastrointestinal Wall: Sulfation of ethinyl estradiol has been shown to occur in the gastrointestinal wall. Therefore, drugs which act as competitive inhibitors for sulfation in the gastrointestinal wall may increase ethinyl estradiol bioavailability.
- Hepatic metabolism: Interactions can occur with drugs that induce microsomal enzymes which can decrease ethinyl estradiol concentrations (e.g., rifampin, barbiturates, phenylbutazone, phenytoin, griseofulvin).
- Interference with Enterohepatic Circulation: Some clinical reports suggest that enteroheptic circulation of estrogens may decrease when certain antibiotic agents are given, which may reduce ethinyl estradiol concentrations (e.g., ampicillin, tetracycline).
- Interference in the Metabolism of Other Drugs: Ethinyl estradiol may interfere with the metabolism of other drugs by inhibiting hepatic microsomal enzymes or by inducing hepatic drug conjugation, particularly glucuronidation. Accordingly, plasma and tissue concentrations may either be increased or decreased, respectively (e.g., cyclosporin, theophylline).
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OVERDOSAGE
Serious ill effects have not been reported following acute ingestion of large doses of oral contraceptives by young children. Overdosage may cause nausea, and withdrawal bleeding may occur in females.
NON-CONTRACEPTIVE HEALTH BENEFITS
The following noncontraceptive health benefits related to the use of oral contraceptives are supported by epidemiological studies which largely utilized oral-contraceptive formulations containing doses exceeding 0.035 mg of ethinyl estradiol or 0.05 mg mestranol.
Effects on menses:
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increased menstrual cycle regularity
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decreased blood loss and decreased incidence of iron-deficiency anemia
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decreased incidence of dysmenorrhea
Effects related to inhibition of ovulation:
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decreased incidence of functional ovarian cysts
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decreased incidence of ectopic pregnancies
Effects from long-term use:
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decreased incidence of fibroadenomas and fibrocystic disease of the breast
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decreased incidence of acute pelvic inflammatory disease
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decreased incidence of endometrial cancer
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decreased incidence of ovarian cancer
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