"What are birth control pills and how do they work?
Birth control pills are also known as oral contraceptives (OCs) or, simply, “the pill.” They offer protection against pregnancy by blocking the union of sperm and egg, thereby prevent"...
Endocrine & metabolic: Amenorrhea, breakthrough bleeding, breast enlargement, breast secretion, breast tenderness, carbohydrate intolerance, lactation decreased (postpartum), glucose tolerance decreased, libido changes, menstrual flow changes, sex hormone-binding globulins (SHBG) increased, spotting, temporary infertility (following discontinuation), thyroid-binding globulin increased, triglycerides increased
Hematologic: Antithrombin III decreased, folate levels decreased, hemolytic uremic syndrome, norepinephrine induced platelet aggregability increased, porphyria, prothrombin increased; factors VII, VIII, IX, and X increased
Renal: Impaired renal function
Miscellaneous: Hemorrhagic eruption
Read the Demulen (ethinyl estradiol and ethynodiol diacetate) Side Effects Center for a complete guide to possible side effects
Ethinyl estradiol: Substrate of CYP3A4 (major), 3A5-7 (minor); Inhibits CYP1A2 (weak), 2B6 (weak), 2C19 (weak), 3A4 (weak)
Acetaminophen: May increase plasma concentration of synthetic estrogens, possibly by inhibiting conjugation. Combination hormonal contraceptives may also decrease the plasma concentration of acetaminophen.
Acitretin: Interferes with the contraceptive effect of microdosed progestin-containing "minipill" preparations. The effect on other progestational contraceptives (eg, implants, injectables) is unknown.
Aminoglutethimide: May increase CYP metabolism of progestins leading to possible decrease in contraceptive effectiveness. Use of a nonhormonal contraceptive product is recommended.
Antibiotics (ampicillin, tetracycline): Pregnancy has been reported following concomitant use, however, pharmacokinetic studies have not shown consistent effects with these antibiotics on plasma concentrations of synthetic steroids. Use of a nonhormonal contraceptive product is recommended.
Anticoagulants: Combination hormonal contraceptives may increase or decrease the effects of coumarin derivatives. Combination hormonal contraceptives may also increase risk of thromboembolic disorders
Anticonvulsants (carbamazepine, felbamate, phenobarbital, phenytoin, topiramate): Increase the metabolism of ethinyl estradiol and/or some progestins, leading to possible decrease in contraceptive effectiveness. Use of a nonhormonal contraceptive product is recommended.
Ascorbic acid: Doses of ascorbic acid (vitamin C) 1 g/day have been reported to increase plasma concentration of synthetic estrogens by ~47%, possibly by inhibiting conjugation; clinical implications are unclear.
Atorvastatin: Atorvastatin increases the AUC for norethindrone and ethinyl estradiol.
Benzodiazepines: Combination hormonal contraceptives may decrease the clearance of some benzodiazepines (alprazolam, chlordiazepoxide, diazepam) and increase the clearance of others (lorazepam, oxazepam, temazepam)
Clofibric acid: Combination hormonal contraceptives may increase the clearance of clofibric acid.
Cyclosporine: Combination hormonal contraceptives may inhibit the metabolism of cyclosporine, leading to increased plasma concentrations; monitor cyclosporine levels
CYP3A4 inducers: CYP3A4 inducers may decrease the levels/effects of ethinyl estradiol. Example inducers include aminoglutethimide, carbamazepine, nafcillin, nevirapine, phenobarbital, phenytoin, and rifamycins.
Griseofulvin: Griseofulvin may induce the metabolism of combination hormonal contraceptives causing menstrual changes; pregnancies have been reported. Use of barrier form of contraception is suggested while on griseofulvin therapy.
Morphine: Combination hormonal contraceptives may increase the clearance of morphine.
Non-nucleoside reverse transcriptase inhibitors (NNRTIs): Nevirapine may decrease plasma levels of combination hormonal contraceptives; use of a nonhormonal contraceptive product is recommended. No data for delavirdine; incomplete data for efavirenz
Prednisolone: Ethinyl estradiol may inhibit the metabolism of prednisolone, leading to increased plasma concentrations.
Protease inhibitors: Amprenavir, lopinavir, nelfinavir, and ritonavir have been shown to decrease plasma levels of combination hormonal contraceptives; use of a nonhormonal contraceptive product is recommended. Indinavir has been shown to increase plasma levels of combination hormonal contraceptives. No data for saquinavir.
Rifampin: Rifampin increases the metabolism of ethinyl estradiol and some progestins (norethindrone) resulting in decreased contraceptive effectiveness and increased menstrual irregularities. Use of a nonhormonal contraceptive product is recommended.
Salicylic acid: Combination hormonal contraceptives may increase the clearance of salicylic acid.
Selegiline: Combination hormonal contraceptives may increase the serum concentration of selegiline.
Theophylline: Ethinyl estradiol may inhibit the metabolism of theophylline, leading to increased plasma concentrations.
ETHANOL / NUTRITION / HERB INTERACTIONS
Food: CNS effects of caffeine may be enhanced if combination hormonal contraceptives are used concurrently with caffeine. Grapefruit juice increases ethinyl estradiol concentrations and would be expected to increase progesterone serum levels as well; clinical implications are unclear.
Herb/Nutraceutical: St John's wort may decrease the effectiveness of combination hormonal contraceptives by inducing hepatic enzymes. Avoid dong quai and black cohosh (have estrogen activity). Avoid saw palmetto, red clover, ginseng.
Last reviewed on RxList: 12/8/2004
This monograph has been modified to include the generic and brand name in many instances.
Additional Demulen Information
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