Drug Interactions between Lo/Ovral and MY-E

MONITOR: Coadministration of chloramphenicol, dalfopristin, erythromycin, or fusidic acid may increase the plasma concentrations of drugs that are substrates of the CYP450 3A4 isoenzyme, by reducing their clearance, as these antibiotics are moderate inhibitors of this isoenzyme. Many estrogen and progestin type medications are CYP450 3A4 substrates. These medications are used for a variety of purposes including, but not limited to, contraception, acne treatment, hormone replacement therapy, and appetite stimulation. When telithromycin, a potent CYP450 3A4 inhibitor, was co-administered with oral contraceptives containing ethinyl estradiol and levonorgestrel, studies showed that the systemic concentration (AUC) of ethinyl estradiol did not change and the AUC of levonorgestrel increased by 50%. The study showed that telithromycin did not interfere with the anti-ovulatory effect of oral contraceptives containing ethinyl estradiol and levonorgestrel.

MANAGEMENT: Caution is advised if chloramphenicol, dalfopristin, erythromycin, or fusidic acid must be used concurrently with medications that undergo metabolism by CYP450 3A4. Patients should be monitored for increased adverse effects from the hormonal treatment if it must be co-administered with one of these antibiotics. Some serious side effects associated with hormonal treatment include, but are not limited to, cardiovascular disease (e.g., venous thromboembolism, myocardial infarction, and stroke); breast cancer; loss of bone mineral density; changes in mood; cholestatic jaundice; and dementia. Some of these side effects are affected by other factors such as medication dosage, concurrent medications, age, smoking status, and other disease states. If concurrent therapy with any of these antibiotics is necessary, please refer to the product labeling for more specific adverse effects to monitor for and counsel the patient and/or the patient's caregiver on the risks and benefits of concurrent therapy.

MONITOR: Estrogenic steroids, but not progestins, undergo enterohepatic cycling. It is possible that antimicrobials may interfere with the enterohepatic recirculation of estrogens by decreasing bacteria in the gastrointestinal tract that are responsible for regenerating parent estrogen molecules following first-pass metabolism. Most of the research regarding this possible interaction has been done with oral contraceptives; however, all estrogens appear to undergo enterohepatic recirculation so theoretically this interaction is a possibility with estrogen containing medications that are being used for alternative purposes. The risk appears to be small, and supportive data are primarily limited to anecdotal evidence from case reports and findings from uncontrolled or poorly controlled studies. Most antimicrobials, except for enzyme inducing medications like the rifamycins and possibly griseofulvin, have not been shown to significantly increase the clearance of estrogens present in combined hormonal contraceptives. It is possible that a small number of women may be more sensitive to the effects of antimicrobials on estrogen disposition in vivo, but risk factors or genetic predispositions have yet to be identified.

MANAGEMENT: If a person is using estrogen for a purpose other than contraception, it is important to note that there is a theoretical possibility of lower levels of systemic estrogen available during treatment with an antibiotic due to interference with enterohepatic cycling. These patients should be counseled to report any changes in efficacy of the hormonal product to their healthcare provider. In the case of contraception specifically, the Centers for Disease Control and Prevention do not consider most broad-spectrum antibiotics to significantly interfere with the effectiveness of combined hormonal contraception. However, the manufacturers of certain combined hormonal contraceptives and/or certain antibiotics do recommend using a back-up method of birth control for varying amounts of time; therefore, consulting the product labeling of each medication involved is advised. Some illnesses, as well as some antibiotics, may cause nausea, vomiting, and/or diarrhea. If the patient vomits within a few hours of taking an oral contraceptive pill, consult the product labeling for instructions on what to do in the event of a missed pill. Some authorities recommend a back-up method of birth control if an individual has persistent vomiting or diarrhea.

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MONITOR: Coadministration of chloramphenicol, dalfopristin, erythromycin, or fusidic acid may increase the plasma concentrations of drugs that are substrates of the CYP450 3A4 isoenzyme, by reducing their clearance, as these antibiotics are moderate inhibitors of this isoenzyme. Many estrogen and progestin type medications are CYP450 3A4 substrates. These medications are used for a variety of purposes including, but not limited to, contraception, acne treatment, hormone replacement therapy, and appetite stimulation. When telithromycin, a potent CYP450 3A4 inhibitor, was co-administered with oral contraceptives containing ethinyl estradiol and levonorgestrel, studies showed that the systemic concentration (AUC) of ethinyl estradiol did not change and the AUC of levonorgestrel increased by 50%. The study showed that telithromycin did not interfere with the anti-ovulatory effect of oral contraceptives containing ethinyl estradiol and levonorgestrel.

MANAGEMENT: Caution is advised if chloramphenicol, dalfopristin, erythromycin, or fusidic acid must be used concurrently with medications that undergo metabolism by CYP450 3A4. Patients should be monitored for increased adverse effects from the hormonal treatment if it must be co-administered with one of these antibiotics. Some serious side effects associated with hormonal treatment include, but are not limited to, cardiovascular disease (e.g., venous thromboembolism, myocardial infarction, and stroke); breast cancer; loss of bone mineral density; changes in mood; cholestatic jaundice; and dementia. Some of these side effects are affected by other factors such as medication dosage, concurrent medications, age, smoking status, and other disease states. If concurrent therapy with any of these antibiotics is necessary, please refer to the product labeling for more specific adverse effects to monitor for and counsel the patient and/or the patient's caregiver on the risks and benefits of concurrent therapy.

MONITOR: Estrogenic steroids, but not progestins, undergo enterohepatic cycling. It is possible that antimicrobials may interfere with the enterohepatic recirculation of estrogens by decreasing bacteria in the gastrointestinal tract that are responsible for regenerating parent estrogen molecules following first-pass metabolism. Most of the research regarding this possible interaction has been done with oral contraceptives; however, all estrogens appear to undergo enterohepatic recirculation so theoretically this interaction is a possibility with estrogen containing medications that are being used for alternative purposes. The risk appears to be small, and supportive data are primarily limited to anecdotal evidence from case reports and findings from uncontrolled or poorly controlled studies. Most antimicrobials, except for enzyme inducing medications like the rifamycins and possibly griseofulvin, have not been shown to significantly increase the clearance of estrogens present in combined hormonal contraceptives. It is possible that a small number of women may be more sensitive to the effects of antimicrobials on estrogen disposition in vivo, but risk factors or genetic predispositions have yet to be identified.

MANAGEMENT: If a person is using estrogen for a purpose other than contraception, it is important to note that there is a theoretical possibility of lower levels of systemic estrogen available during treatment with an antibiotic due to interference with enterohepatic cycling. These patients should be counseled to report any changes in efficacy of the hormonal product to their healthcare provider. In the case of contraception specifically, the Centers for Disease Control and Prevention do not consider most broad-spectrum antibiotics to significantly interfere with the effectiveness of combined hormonal contraception. However, the manufacturers of certain combined hormonal contraceptives and/or certain antibiotics do recommend using a back-up method of birth control for varying amounts of time; therefore, consulting the product labeling of each medication involved is advised. Some illnesses, as well as some antibiotics, may cause nausea, vomiting, and/or diarrhea. If the patient vomits within a few hours of taking an oral contraceptive pill, consult the product labeling for instructions on what to do in the event of a missed pill. Some authorities recommend a back-up method of birth control if an individual has persistent vomiting or diarrhea.

Switch to consumer interaction data