DRUG INTERACTIONS 9. Drug Interactions
Changes in Contraceptive Effectiveness Associated with Coadministration of Other Products:
Contraceptive effectiveness may be reduced when hormonal contraceptives are coadministered with antibiotics, anticonvulsants, and other drugs that increase the metabolism of contraceptive steroids. This could result in unintended pregnancy or unscheduled bleeding. Examples include rifampin, rifabutin, barbiturates, primidone, phenylbutazone, phenytoin, dexamethasone, carbamazepine, felbamate, oxcarbazepine, topiramate, griseofulvin, and modafinil. In such cases a nonhormonal back-up method of birth control should be considered.
Several cases of contraceptive failure and unscheduled bleeding have been reported in the literature with concomitant administration of antibiotics such as ampicillin and other penicillins, and tetracyclines. However, clinical pharmacology studies investigating drug interactions between combined oral contraceptives and these antibiotics have reported inconsistent results. Enterohepatic recirculation of estrogens may also be decreased by substances that reduce gut transit time.
Several of the anti-HIV protease inhibitors have been studied with coadministration of oral combination hormonal contraceptives; significant changes (increase and decrease) in the plasma levels of the estrogen and progestin have been noted in some cases. The safety and efficacy of oral contraceptive products may be affected with coadministration of anti-HIV protease inhibitors. Health care professionals should refer to the label of the individual anti-HIV protease inhibitors for further drug-drug interaction information.
Herbal products containing St. John's Wort (Hypericum perforatum) may induce hepatic enzymes (cytochrome P 450) and p-glycoprotein transporter and may reduce the effectiveness of contraceptive steroids. This may also result in unscheduled bleeding.
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OVERDOSAGE
Symptoms of oral contraceptive overdosage in adults and children may include nausea, vomiting, breast tenderness, dizziness, abdominal pain, drowsiness/fatigue; withdrawal bleeding may occur in females. There is no specific antidote and further treatment of overdose, if necessary, is directed to the symptoms.
NONCONTRACEPTIVE 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 of mestranol.
Effects on menses:
- May decrease blood loss and may decrease the incidence of iron-deficiency anemia
May decrease incidence of dysmenorrhea
Effects related to inhibition of ovulation:
- May decrease incidence of functional ovarian cysts
May decrease incidence of ectopic pregnancies
Effects from long-term use:
- May decrease incidence of fibroadenomas and fibrocystic disease of the breast
May decrease incidence of acute pelvic inflammatory disease
May decrease incidence of endometrial cancer
May decrease incidence of ovarian cancer
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CONTRAINDICATIONS
Combination oral contraceptives should not be used in women with any of the following conditions:
Thrombophlebitis or thromboembolic disorders
History of deep-vein thrombophlebitis or thromboembolic disorders
Cerebrovascular or coronary artery disease (current or past history)
Valvular heart disease with thrombogenic complications
Thrombogenic rhythm disorders
Hereditary or acquired thrombophilias
Major surgery with prolonged immobilization
Diabetes with vascular involvement
Headaches with focal neurological symptoms such as aura
Uncontrolled hypertension
Known or suspected carcinoma of the breast or personal history of breast cancer
Carcinoma of the endometrium or other known or suspected estrogen-dependent neoplasia
Undiagnosed abnormal genital bleeding
Cholestatic jaundice of pregnancy or jaundice with prior pill use
Hepatic adenomas or carcinomas, or active liver disease
Known or suspected pregnancy
Hypersensitivity to any of the components of LYBREL
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