30 - Drugs that May Reduce Combined Hormonal Contraceptive Efficacy

Interacting Drug Documentation Antituberculous     Rifampin Established; reduced efficacy if <50 microg EE Antifungals     Griseofulvin Strongly suspected Anticonvulsants and sedatives     Phenytoin, mephenytoin, phenobarbital, primidone, carbamzepine, ethosuximide Strongly suspected; reduced efficacy if <50 microg EE; trials lacking Antibiotics     Tetracycline, doxycycline Two small studies find no association   Penicillins No association documented   Ciprofloxacin No effect on efficacy of a 30 microg EE + desogestrel pill   Ofloxacin No effect on efficacy of a 30 microg EE + levonorgestrel pill Antiretrovirals Variable effects; see manufacturer or other

EE = ethinyl estradiol.

29 - Drugs Whose Effectiveness Is Influenced by Combination Oral Contraceptives

Interacting Drug Documentation Management Analgesics       Acetaminophen Adequate Larger doses of analgesic may be required   Aspirin Probable Larger doses of analgesic may be required   Meperidine Suspected Smaller doses of analgesic may be required   Morphine Probable Larger doses of analgesic may be required Anticoagulants       Dicumarol, warfarin Controversial   Antidepressants       Imipramine Suspected Decrease dosage about a third Tranquilizers       Diazepam, alprazolam Suspected Decrease dose   Temazepam Possible May need to increase dose   Other benzodiazepines Suspected Observe for increased effect Anti-inflammatories       Corticosteroids Adequate Watch for potentiation of effects, decrease dose accordingly Bronchodilators       Aminophylline, theophylline, caffeine Adequate Reduce starting dose by a third Antihypertensives       Cyclopenthiazide Adequate Increase dose   Metoprolol Suspected May need to lower dose Other       Troleandomycin Suspected liver damage Avoid   Cyclosporine Possible May use smaller dose   Antiretrovirals Variable See manufacturer or other