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Drug Interactions between Lybrel and Zelboraf

This report displays the potential drug interactions for the following 2 drugs:

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Moderate

ethinyl estradiol vemurafenib

Applies to: Lybrel (ethinyl estradiol / levonorgestrel) and Zelboraf (vemurafenib)

ADDITIONAL CONTRACEPTION RECOMMENDED: 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response to estrogens and progestins should be monitored more closely whenever a CYP450 3A4 inducer is added to or withdrawn from therapy, and the hormone dosage adjusted as necessary. For patients receiving hormonal contraceptives, additional or alternative non-hormonal birth control may be advisable during concomitant therapy with CYP450 3A4 inducers. Additional or alternative non-hormonal birth control may be recommended beyond discontinuation of the CYP450 3A4 inducer(s). Individual product labeling should be consulted for specific time frames. Intrauterine systems are unlikely to be significantly affected because of their local action. Input from a gynecologist or similar expert on adequate contraception, including emergency contraception, should be sought as needed. 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.

References

  1. Crawford P, Chadwick DJ, Martin C, et al. "The interaction of phenytoin and carbamazepine with combined oral contraceptive steroids." Br J Clin Pharmacol 30 (1990): 892-6
  2. Venkatesan K "Pharmacokinetic drug interactions with rifampicin." Clin Pharmacokinet 22 (1992): 47-65
  3. Borcherding SM, Baciewicz AM, Self TH "Update on rifampin drug interactions." Arch Intern Med 152 (1992): 711-6
  4. Weber JC "Interaction between oral contraceptives and griseofulvin." Br Med J 288 (1984): 1125-6
  5. McDaniel PA, Caldroney RD "Oral contraceptives and griseofulvin interaction." Drug Intell Clin Pharm 20 (1986): 384
  6. Cote J "Interaction of griseofulvin and oral contraceptives." J Am Acad Dermatol 22 (1990): 124-5
  7. Baciewicz AM "Oral contraceptive drug interactions." Ther Drug Monit 7 (1985): 26-35
  8. Skolnick JL, Stoler BS, Katz DB, Anderson WH "Rifampin, oral contraceptives, and pregnancy." JAMA 236 (1976): 1382
  9. Lundgren S, Lonning PE, Aakvaag A, Kvinnsland S, Lnning PE "Influence of aminoglutethimide on the metabolism of medroxyprogesterone acetate and megestrol acetate in postmenopausal patients with advanced breast cancer." Cancer Chemother Pharmacol 27 (1990): 101-5
  10. Halpenny O, Bye A, Cranny A, Feely J, Daly PA "Influence of aminoglutethimide on plasma levels of medroxyprogesterone acetate." Med Oncol Tumor Pharmacother 7 (1990): 241-7
  11. Mumford JP "Letter: Drugs affecting oral contraceptives." Br Med J 2 (1974): 333-4
  12. Back DJ, Bates M, Bowden A, et al. "The interaction of phenobarbital and other anticonvulsants with oral contraceptive steroid therapy." Contraception 22 (1980): 495-503
  13. Dossetor J "Drug interactions with oral contraceptives." Br Med J 4 (1975): 467-8
  14. Baciewicz AM, Self TH "Rifampin drug interactions." Arch Intern Med 144 (1984): 1667-71
  15. Nocke-finck L "Effects of rifampicin on menstral cycle and on estrogen excretion in patients taking oral contraceptives." JAMA 226 (1973): 378
  16. Bolt HM, Bolt M, Kappus H "Interaction of rifampicin treatment with pharmacokinetics and metabolism of ethinyloestradiol in man." Acta Endocrinol (Copenh) 85 (1977): 189-97
  17. Back DJ, Breckenridge AM, Crawford FE, et al. "The effect of rifampicin on the pharmacokinetics of ethynylestradiol in women." Contraception 21 (1980): 135-43
  18. Furlan AJ, Rothner AD "Anti-epileptic drugs and failure of oral contraceptives." Lancet 1 (1974): 1113
  19. Coulam CB, Annegers JF "Do anticonvulsants reduce the efficacy of oral contraceptives?" Epilepsia 20 (1979): 519-26
  20. Szoka PR, Edgren RA "Drug interactions with oral contraceptives: compilation and analysis of an adverse experience report database." Fertil Steril 49 (1988): s31-8
  21. Mattson RH, Cramer JA, Darney PD, Naftolin F "Use of oral contraceptives by women with epilepsy." JAMA 256 (1986): 238-40
  22. van Dijke CP, Weber JC "Interaction between oral contraceptives and griseofulvin." Br Med J (Clin Res Ed) 288 (1984): 1125-6
  23. Laengner H, Detering K "Letter: Anti-epileptic drugs and failure of oral contraceptives." Lancet 2 (1974): 600
  24. Janz D, Schmidt D "Letter: Anti-epileptic drugs and failure of oral contraceptives." Lancet 1 (1974): 1113
  25. Curran MA "Drug interactions with the pill." Med J Aust 144 (1986): 670-1
  26. Back DJ, Orme ML "Pharmacokinetic drug interactions with oral contraceptives." Clin Pharmacokinet 18 (1990): 472-84
  27. D'Arcy PF "Drug interactions with oral contraceptives." Drug Intell Clin Pharm 20 (1986): 353-62
  28. Notelovitz M, Tjapkes J, Ware M "Interaction between estrogen and dilantin in a menopausal woman." N Engl J Med 304 (1981): 788-9
  29. "Product Information. Premarin (conjugated estrogens)." Wyeth-Ayerst Laboratories PROD (2001):
  30. Strayhorn VA, Baciewicz AM, Self TH "Update on rifampin drug interactions, III." Arch Intern Med 157 (1997): 2453-8
  31. Michalets EL "Update: clinically significant cytochrome P-450 drug interactions." Pharmacotherapy 18 (1998): 84-112
  32. Back DJ, Breckenridge AM, Crawford FE, MacIver M, Orne ML, Rowe PH "Interindividual variation and drug interactions with hormonal steroid contraceptives." Drugs 21 (1981): 46-61
  33. LeBel M, Masson E, Guilbert E, Colborn D, Paquet F, Allard S, Vallee F, Narang PK "Effects of rifabutin and rifampicin on the pharmacokinetics of ethinylestradiol and norethindrone." J Clin Pharmacol 38 (1998): 1042-50
  34. Barditch-Crovo P, Trapnell CB, Ette E, et al. "The effects of rifampin and rifabutin on the pharmacokinetics and pharmacodynamics of a combination oral contraceptive." Clin Pharmacol Ther 65 (1999): 428-38
  35. Weisberg E "Interactions between oral contraceptives and antifungals antibacterials - Is contraceptive failure the result?." Clin Pharmacokinet 36 (1999): 309-13
  36. Klosterskov Jensen P, Saano V, Haring P, Svenstrup B, Menge GP "Possible interaction between oxcarbazepine and an oral contraceptive." Epilepsia 33 (1992): 1149-52
  37. Wilbur K, Ensom MHH "Pharmacokinetic drug interactions between oral contraceptives and second-generation anticonvulsants." Clin Pharmacokinet 38 (2000): 355-65
  38. Durr D, Stieger B, KullakUblick GA, Rentsch KM, Steinert HC, Meier PJ, Fattinger K "St John's Wort induces intestinal P-glycoprotein/MDR1 and intestinal and hepatic CYP3A4." Clin Pharmacol Ther 68 (2000): 598-604
  39. Weaver K, Glasier A "Interaction between broad-spectrum antibiotics and the combined oral contraceptive pill: a literature review." Contraception 59 (1999): 71-8
  40. Zachariassen RD "Loss of oral contraceptive efficacy by concurrent antibiotic administration." Women Health 22 (1994): 17-26
  41. Dickinson BD, Altman RD, Nielsen NH, Sterling ML "Drug interactions between oral contraceptives and antibiotics." Obstet Gynecol 98(5 Pt 1) (2001): 853-60
  42. "Unwanted pregnancy on self-medication with St John's wort despite hormonal contraception." Br J Clin Pharmacol 55 (2003): 112-113
  43. Pfrunder A, Schiesser M, Gerber S, Haschke M, Bitzer J, Drewe J "Interaction of St John's wort with low-dose oral contraceptive therapy: a randomized controlled trial." Br J Clin Pharmacol 56 (2003): 683-90
  44. Hall SD, Wang Z, Huang SM, et al. "The interaction between St John's wort and an oral contraceptive." Clin Pharmacol Ther 74 (2003): 525-35
  45. Gorski JC, Hamman MA, Wang Z, Vasvada N, Huang S, Hall SD "The effect of St. John's wort on the efficacy of oral contraception." Clin Pharmacol Ther 71 (2002): P25
  46. Schwarz UI, Buschel B, Kirch W "Failure of oral contraceptives because of St. John's wort." Eur J Clin Pharmacol 57 (2001): A25
  47. Faculty of Sexual & Reproductive Healthcare "FSRH Clinical Guidance: Drug Interactions with Hormonal Contraception. file:///C:/Users/df033684/Downloads/ceuguidancedruginteractionshormonal.pdf" (2016):
View all 47 references

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Moderate

levonorgestrel vemurafenib

Applies to: Lybrel (ethinyl estradiol / levonorgestrel) and Zelboraf (vemurafenib)

ADDITIONAL CONTRACEPTION RECOMMENDED: 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. For patients receiving hormonal contraceptives, additional or alternative non-hormonal birth control may be advisable during concomitant therapy with CYP450 3A4 inducers. Additional or alternative non-hormonal birth control may be recommended beyond discontinuation of the CYP450 3A4 inducer(s). Individual product labeling should be consulted for specific time frames. Intrauterine systems are unlikely to be significantly affected because of their local action. Input from a gynecologist or similar expert on adequate contraception, including emergency contraception, should be sought as needed. 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.

References

  1. Crawford P, Chadwick DJ, Martin C, et al. "The interaction of phenytoin and carbamazepine with combined oral contraceptive steroids." Br J Clin Pharmacol 30 (1990): 892-6
  2. Venkatesan K "Pharmacokinetic drug interactions with rifampicin." Clin Pharmacokinet 22 (1992): 47-65
  3. Borcherding SM, Baciewicz AM, Self TH "Update on rifampin drug interactions." Arch Intern Med 152 (1992): 711-6
  4. Weber JC "Interaction between oral contraceptives and griseofulvin." Br Med J 288 (1984): 1125-6
  5. McDaniel PA, Caldroney RD "Oral contraceptives and griseofulvin interaction." Drug Intell Clin Pharm 20 (1986): 384
  6. Cote J "Interaction of griseofulvin and oral contraceptives." J Am Acad Dermatol 22 (1990): 124-5
  7. Baciewicz AM "Oral contraceptive drug interactions." Ther Drug Monit 7 (1985): 26-35
  8. Skolnick JL, Stoler BS, Katz DB, Anderson WH "Rifampin, oral contraceptives, and pregnancy." JAMA 236 (1976): 1382
  9. Lundgren S, Lonning PE, Aakvaag A, Kvinnsland S, Lnning PE "Influence of aminoglutethimide on the metabolism of medroxyprogesterone acetate and megestrol acetate in postmenopausal patients with advanced breast cancer." Cancer Chemother Pharmacol 27 (1990): 101-5
  10. Halpenny O, Bye A, Cranny A, Feely J, Daly PA "Influence of aminoglutethimide on plasma levels of medroxyprogesterone acetate." Med Oncol Tumor Pharmacother 7 (1990): 241-7
  11. Mumford JP "Letter: Drugs affecting oral contraceptives." Br Med J 2 (1974): 333-4
  12. Back DJ, Bates M, Bowden A, et al. "The interaction of phenobarbital and other anticonvulsants with oral contraceptive steroid therapy." Contraception 22 (1980): 495-503
  13. Dossetor J "Drug interactions with oral contraceptives." Br Med J 4 (1975): 467-8
  14. Baciewicz AM, Self TH "Rifampin drug interactions." Arch Intern Med 144 (1984): 1667-71
  15. Nocke-finck L "Effects of rifampicin on menstral cycle and on estrogen excretion in patients taking oral contraceptives." JAMA 226 (1973): 378
  16. Bolt HM, Bolt M, Kappus H "Interaction of rifampicin treatment with pharmacokinetics and metabolism of ethinyloestradiol in man." Acta Endocrinol (Copenh) 85 (1977): 189-97
  17. Back DJ, Breckenridge AM, Crawford FE, et al. "The effect of rifampicin on the pharmacokinetics of ethynylestradiol in women." Contraception 21 (1980): 135-43
  18. Furlan AJ, Rothner AD "Anti-epileptic drugs and failure of oral contraceptives." Lancet 1 (1974): 1113
  19. Coulam CB, Annegers JF "Do anticonvulsants reduce the efficacy of oral contraceptives?" Epilepsia 20 (1979): 519-26
  20. Szoka PR, Edgren RA "Drug interactions with oral contraceptives: compilation and analysis of an adverse experience report database." Fertil Steril 49 (1988): s31-8
  21. Mattson RH, Cramer JA, Darney PD, Naftolin F "Use of oral contraceptives by women with epilepsy." JAMA 256 (1986): 238-40
  22. van Dijke CP, Weber JC "Interaction between oral contraceptives and griseofulvin." Br Med J (Clin Res Ed) 288 (1984): 1125-6
  23. Laengner H, Detering K "Letter: Anti-epileptic drugs and failure of oral contraceptives." Lancet 2 (1974): 600
  24. Janz D, Schmidt D "Letter: Anti-epileptic drugs and failure of oral contraceptives." Lancet 1 (1974): 1113
  25. Curran MA "Drug interactions with the pill." Med J Aust 144 (1986): 670-1
  26. Back DJ, Orme ML "Pharmacokinetic drug interactions with oral contraceptives." Clin Pharmacokinet 18 (1990): 472-84
  27. D'Arcy PF "Drug interactions with oral contraceptives." Drug Intell Clin Pharm 20 (1986): 353-62
  28. Notelovitz M, Tjapkes J, Ware M "Interaction between estrogen and dilantin in a menopausal woman." N Engl J Med 304 (1981): 788-9
  29. "Product Information. Premarin (conjugated estrogens)." Wyeth-Ayerst Laboratories PROD (2001):
  30. Strayhorn VA, Baciewicz AM, Self TH "Update on rifampin drug interactions, III." Arch Intern Med 157 (1997): 2453-8
  31. Michalets EL "Update: clinically significant cytochrome P-450 drug interactions." Pharmacotherapy 18 (1998): 84-112
  32. Back DJ, Breckenridge AM, Crawford FE, MacIver M, Orne ML, Rowe PH "Interindividual variation and drug interactions with hormonal steroid contraceptives." Drugs 21 (1981): 46-61
  33. LeBel M, Masson E, Guilbert E, Colborn D, Paquet F, Allard S, Vallee F, Narang PK "Effects of rifabutin and rifampicin on the pharmacokinetics of ethinylestradiol and norethindrone." J Clin Pharmacol 38 (1998): 1042-50
  34. Barditch-Crovo P, Trapnell CB, Ette E, et al. "The effects of rifampin and rifabutin on the pharmacokinetics and pharmacodynamics of a combination oral contraceptive." Clin Pharmacol Ther 65 (1999): 428-38
  35. Weisberg E "Interactions between oral contraceptives and antifungals antibacterials - Is contraceptive failure the result?." Clin Pharmacokinet 36 (1999): 309-13
  36. Klosterskov Jensen P, Saano V, Haring P, Svenstrup B, Menge GP "Possible interaction between oxcarbazepine and an oral contraceptive." Epilepsia 33 (1992): 1149-52
  37. Wilbur K, Ensom MHH "Pharmacokinetic drug interactions between oral contraceptives and second-generation anticonvulsants." Clin Pharmacokinet 38 (2000): 355-65
  38. Durr D, Stieger B, KullakUblick GA, Rentsch KM, Steinert HC, Meier PJ, Fattinger K "St John's Wort induces intestinal P-glycoprotein/MDR1 and intestinal and hepatic CYP3A4." Clin Pharmacol Ther 68 (2000): 598-604
  39. Weaver K, Glasier A "Interaction between broad-spectrum antibiotics and the combined oral contraceptive pill: a literature review." Contraception 59 (1999): 71-8
  40. Zachariassen RD "Loss of oral contraceptive efficacy by concurrent antibiotic administration." Women Health 22 (1994): 17-26
  41. Dickinson BD, Altman RD, Nielsen NH, Sterling ML "Drug interactions between oral contraceptives and antibiotics." Obstet Gynecol 98(5 Pt 1) (2001): 853-60
  42. "Unwanted pregnancy on self-medication with St John's wort despite hormonal contraception." Br J Clin Pharmacol 55 (2003): 112-113
  43. Pfrunder A, Schiesser M, Gerber S, Haschke M, Bitzer J, Drewe J "Interaction of St John's wort with low-dose oral contraceptive therapy: a randomized controlled trial." Br J Clin Pharmacol 56 (2003): 683-90
  44. Hall SD, Wang Z, Huang SM, et al. "The interaction between St John's wort and an oral contraceptive." Clin Pharmacol Ther 74 (2003): 525-35
  45. Gorski JC, Hamman MA, Wang Z, Vasvada N, Huang S, Hall SD "The effect of St. John's wort on the efficacy of oral contraception." Clin Pharmacol Ther 71 (2002): P25
  46. Schwarz UI, Buschel B, Kirch W "Failure of oral contraceptives because of St. John's wort." Eur J Clin Pharmacol 57 (2001): A25
  47. Faculty of Sexual & Reproductive Healthcare "FSRH Clinical Guidance: Drug Interactions with Hormonal Contraception. file:///C:/Users/df033684/Downloads/ceuguidancedruginteractionshormonal.pdf" (2016):
View all 47 references

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Drug and food interactions

Moderate

levonorgestrel food

Applies to: Lybrel (ethinyl estradiol / levonorgestrel)

MONITOR: Grapefruit juice may increase the plasma concentrations of orally administered drugs that are substrates of the CYP450 3A4 isoenzyme. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Because grapefruit juice inhibits primarily intestinal rather than hepatic CYP450 3A4, the magnitude of interaction is greatest for those drugs that undergo significant presystemic metabolism by CYP450 3A4 (i.e., drugs with low oral bioavailability). In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. Pharmacokinetic interactions involving grapefruit juice are also subject to a high degree of interpatient variability, thus the extent to which a given patient may be affected is difficult to predict.

MANAGEMENT: Patients who regularly consume grapefruit or grapefruit juice should be monitored for adverse effects and altered plasma concentrations of drugs that undergo significant presystemic metabolism by CYP450 3A4. Grapefruit and grapefruit juice should be avoided if an interaction is suspected. Orange juice is not expected to interact with these drugs.

References

  1. Edgar B, Bailey D, Bergstrand R, et al. "Acute effects of drinking grapefruit juice on the pharmacokinetics and dynamics on felodipine and its potential clinical relevance." Eur J Clin Pharmacol 42 (1992): 313-7
  2. Jonkman JH, Sollie FA, Sauter R, Steinijans VW "The influence of caffeine on the steady-state pharmacokinetics of theophylline." Clin Pharmacol Ther 49 (1991): 248-55
  3. Bailey DG, Arnold JM, Munoz C, Spence JD "Grapefruit juice--felodipine interaction: mechanism, predictability, and effect of naringin." Clin Pharmacol Ther 53 (1993): 637-42
  4. Bailey DG, Arnold JMO, Spence JD "Grapefruit juice and drugs - how significant is the interaction." Clin Pharmacokinet 26 (1994): 91-8
  5. Sigusch H, Hippius M, Henschel L, Kaufmann K, Hoffmann A "Influence of grapefruit juice on the pharmacokinetics of a slow release nifedipine formulation." Pharmazie 49 (1994): 522-4
  6. Bailey DG, Arnold JM, Strong HA, Munoz C, Spence JD "Effect of grapefruit juice and naringin on nisoldipine pharmacokinetics." Clin Pharmacol Ther 54 (1993): 589-94
  7. Yamreudeewong W, Henann NE, Fazio A, Lower DL, Cassidy TG "Drug-food interactions in clinical practice." J Fam Pract 40 (1995): 376-84
  8. "Grapefruit juice interactions with drugs." Med Lett Drugs Ther 37 (1995): 73-4
  9. Hukkinen SK, Varhe A, Olkkola KT, Neuvonen PJ "Plasma concentrations of triazolam are increased by concomitant ingestion of grapefruit juice." Clin Pharmacol Ther 58 (1995): 127-31
  10. Min DI, Ku YM, Geraets DR, Lee HC "Effect of grapefruit juice on the pharmacokinetics and pharmacodynamics of quinidine in healthy volunteers." J Clin Pharmacol 36 (1996): 469-76
  11. Majeed A, Kareem A "Effect of grapefruit juice on cyclosporine pharmacokinetics." Pediatr Nephrol 10 (1996): 395
  12. Clifford CP, Adams DA, Murray S, Taylor GW, Wilkins MR, Boobis AR, Davies DS "Pharmacokinetic and cardiac effects of terfenadine after inhibition of its metabolism by grapefruit juice." Br J Clin Pharmacol 42 (1996): p662
  13. Josefsson M, Zackrisson AL, Ahlner J "Effect of grapefruit juice on the pharmacokinetics of amlodipine in healthy volunteers." Eur J Clin Pharmacol 51 (1996): 189-93
  14. Kantola T, Kivisto KT, Neuvonen PJ "Grapefruit juice greatly increases serum concentrations of lovastatin and lovastatin acid." Clin Pharmacol Ther 63 (1998): 397-402
  15. Ozdemir M, Aktan Y, Boydag BS, Cingi MI, Musmul A "Interaction between grapefruit juice and diazepam in humans." Eur J Drug Metab Pharmacokinet 23 (1998): 55-9
  16. Bailey DG, Malcolm J, Arnold O, Spence JD "Grapefruit juice-drug interactions." Br J Clin Pharmacol 46 (1998): 101-10
  17. Bailey DG, Kreeft JH, Munoz C, Freeman DJ, Bend JR "Grapefruit juice felodipine interaction: Effect of naringin and 6',7'-dihydroxybergamottin in humans." Clin Pharmacol Ther 64 (1998): 248-56
  18. Garg SK, Kumar N, Bhargava VK, Prabhakar SK "Effect of grapefruit juice on carbamazepine bioavailability in patients with epilepsy." Clin Pharmacol Ther 64 (1998): 286-8
  19. Lilja JJ, Kivisto KT, Neuvonen PJ "Grapefruit juice-simvastatin interaction: Effect on serum concentrations of simvastatin, simvastatin acid, and HMG-CoA reductase inhibitors." Clin Pharmacol Ther 64 (1998): 477-83
  20. Fuhr U, Maier-Bruggemann A, Blume H, et al. "Grapefruit juice increases oral nimodipine bioavailability." Int J Clin Pharmacol Ther 36 (1998): 126-32
  21. Lilja JJ, Kivisto KT, Neuvonen PJ "Grapefruit juice increases serum concentrations of atorvastatin and has no effect on pravastatin." Clin Pharmacol Ther 66 (1999): 118-27
  22. Eagling VA, Profit L, Back DJ "Inhibition of the CYP3A4-mediated metabolism and P-glycoprotein-mediated transport of the HIV-I protease inhibitor saquinavir by grapefruit juice components." Br J Clin Pharmacol 48 (1999): 543-52
  23. Damkier P, Hansen LL, Brosen K "Effect of diclofenac, disulfiram, itraconazole, grapefruit juice and erythromycin on the pharmacokinetics of quinidine." Br J Clin Pharmacol 48 (1999): 829-38
  24. Lee AJ, Chan WK, Harralson AF, Buffum J, Bui BCC "The effects of grapefruit juice on sertraline metabolism: An in vitro and in vivo study." Clin Ther 21 (1999): 1890-9
  25. Dresser GK, Spence JD, Bailey DG "Pharmacokinetic-pharmacodynamic consequences and clinical relevance of cytochrome P450 3A4 inhibition." Clin Pharmacokinet 38 (2000): 41-57
  26. Gunston GD, Mehta U "Potentially serious drug interactions with grapefruit juice." S Afr Med J 90 (2000): 41
  27. Takanaga H, Ohnishi A, Maatsuo H, et al. "Pharmacokinetic analysis of felodipine-grapefruit juice interaction based on an irreversible enzyme inhibition model." Br J Clin Pharmacol 49 (2000): 49-58
  28. Libersa CC, Brique SA, Motte KB, et al. "Dramatic inhibition of amiodarone metabolism induced by grapefruit juice." Br J Clin Pharmacol 49 (2000): 373-8
  29. Bailey DG, Dresser GR, Kreeft JH, Munoz C, Freeman DJ, Bend JR "Grapefruit-felodipine interaction: Effect of unprocessed fruit and probable active ingredients." Clin Pharmacol Ther 68 (2000): 468-77
  30. Zaidenstein R, Soback S, Gips M, Avni B, Dishi V, Weissgarten Y, Golik A, Scapa E "Effect of grapefruit juice on the pharmacokinetics of losartan and its active metabolite E3174 in healthy volunteers." Ther Drug Monit 23 (2001): 369-73
  31. Sato J, Nakata H, Owada E, Kikuta T, Umetsu M, Ito K "Influence of usual intake of dietary caffeine on single-dose kinetics of theophylline in healthy human subjects." Eur J Clin Pharmacol 44 (1993): 295-8
  32. Flanagan D "Understanding the grapefruit-drug interaction." Gen Dent 53 (2005): 282-5; quiz 286
View all 32 references

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Minor

ethinyl estradiol food

Applies to: Lybrel (ethinyl estradiol / levonorgestrel)

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.

References

  1. Weber A, Jager R, Borner A, et al. "Can grapefruit juice influence ethinyl estradiol bioavailability?" Contraception 53 (1996): 41-7
  2. Schubert W, Eriksson U, Edgar B, Cullberg G, Hedner T "Flavonoids in grapefruit juice inhibit the in vitro hepatic metabolism of 17B-estradiol." Eur J Drug Metab Pharmacokinet 20 (1995): 219-24

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Minor

ethinyl estradiol food

Applies to: Lybrel (ethinyl estradiol / levonorgestrel)

The central nervous system effects and blood levels of ethanol may be increased in patients taking oral contraceptives, although data are lacking and reports are contradictory. The mechanism may be due to enzyme inhibition. Consider counseling women about this interaction which is unpredictable.

References

  1. Hobbes J, Boutagy J, Shenfield GM "Interactions between ethanol and oral contraceptive steroids." Clin Pharmacol Ther 38 (1985): 371-80

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Minor

levonorgestrel food

Applies to: Lybrel (ethinyl estradiol / levonorgestrel)

The central nervous system effects and blood levels of ethanol may be increased in patients taking oral contraceptives, although data are lacking and reports are contradictory. The mechanism may be due to enzyme inhibition. Consider counseling women about this interaction which is unpredictable.

References

  1. Hobbes J, Boutagy J, Shenfield GM "Interactions between ethanol and oral contraceptive steroids." Clin Pharmacol Ther 38 (1985): 371-80

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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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