17 Aug 2010
conjugated estrogens ↔ oxcarbazepine
Applies to: Enjuvia (conjugated estrogens), Trileptal (oxcarbazepine)
MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of estrogens and progestins. Estrogens have been shown in in vitro and in vivo studies to be partially metabolized by CYP450 3A4, and other steroids including progestins are also believed to undergo metabolism by this isoenzyme. The interaction has been reported primarily with oral contraceptives. There have been case reports of menstrual breakthrough bleeding or unwanted pregnancy in women receiving low-dose oral contraceptives following the addition of known CYP450 3A4 inducers such as carbamazepine, phenobarbital, phenytoin, rifampin, and St. John's wort. Inadequate response to estrogen replacement therapy has also been reported in a patient treated with phenytoin. Aminoglutethimide, a CYP450 3A4 inducer, has been shown to decrease medroxyprogesterone and megestrol serum levels by 74% in six patients stabilized on their progestin regimen.
MANAGEMENT: Pharmacologic response to estrogens and progestins should be monitored more closely whenever a CYP450 3A4 inducer is added to or withdrawn from therapy, and the hormone dosage adjusted as necessary. Patients should be advised to notify their physician if they experience inadequate control of symptoms associated with estrogen deficiency (e.g., nocturnal sweating, vasomotor disturbances, atrophic vaginitis) or changes in the uterine bleeding profile.
Other drugs that your selected drugs interact with
Enjuvia (conjugated estrogens) interacts with more than 100 other drugs.
Trileptal (oxcarbazepine) interacts with more than 300 other drugs.
Interactions between your selected drugs and food
conjugated estrogens ↔ food
Applies to: Enjuvia (conjugated estrogens)
The coadministration with grapefruit juice may increase the bioavailability of oral estrogens. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. In a small, randomized, crossover study, the administration of ethinyl estradiol with grapefruit juice (compared to herbal tea) increased peak plasma drug concentration (Cmax) by 37% and area under the concentration-time curve (AUC) by 28%. Based on these findings, grapefruit juice is unlikely to affect the overall safety profile of ethinyl estradiol. However, as with other drug interactions involving grapefruit juice, the pharmacokinetic alterations are subject to a high degree of interpatient variability. Also, the effect on other estrogens has not been studied.
Take care.-
Read more: http://www.drugs.com/interactions-check.php?drug_list=2360-2398,1765-1129#ixzz0wp3JXQY8