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Drug Interactions between atazanavir / cobicistat and Eperbel-S

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

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Interactions between your drugs

Major

ergotamine atazanavir

Applies to: Eperbel-S (belladonna / ergotamine / phenobarbital) and atazanavir / cobicistat

CONTRAINDICATED: Coadministration with protease inhibitors (PIs), particularly ritonavir, may significantly increase the plasma concentrations of ergot derivatives. The mechanism is PI inhibition of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of ergotamine and related drugs. Clinical ergotism, occasionally resulting in surgical amputation or death, has been reported in patients receiving ergotamine tartrate with ritonavir, indinavir, and/or nelfinavir. Even small, single doses of ergotamine have been involved in clinically significant interactions.

MANAGEMENT: Given the potential for ergot toxicity characterized by peripheral vasospasm, ischemia, thrombosis, tachycardia and hypertension, concomitant use of ergot derivatives with protease inhibitors is considered contraindicated.

References

  1. "Product Information. D.H.E. 45 (dihydroergotamine)." Sandoz Pharmaceuticals Corporation PROD (2002):
  2. "Product Information. Norvir (ritonavir)." Abbott Pharmaceutical PROD (2001):
  3. "Product Information. Crixivan (indinavir)." Merck & Co., Inc PROD (2001):
  4. "Product Information. Viracept (nelfinavir)." Agouron Pharma Inc PROD (2001):
  5. "Product Information. Migranal (dihydroergotamine nasal)." Novartis Pharmaceuticals PROD (2001):
  6. Rosenthal E, Sala F, Chichmanian RM, Batt M, Cassuto JP "Ergotism related to concurrent administration of ergotamine tartrate and indinavir." JAMA 281 (1999): 987
  7. Liaudet L, Buclin T, Jaccard C, Eckert P "Severe ergotism associated with interaction between ritonavir and ergotamine." Br Med J 318 (1999): 771
  8. "Product Information. Agenerase (amprenavir)." Glaxo Wellcome PROD (2001):
  9. Caballero-Granado FJ, Viciana P, Cordero E, Gomez-Vera MJ, del Nozal M, Lopez-Cortes LF "Ergotism related to concurrent administration of ergotamine tartrate and ritonavir in an AIDS patient." Antimicrob Agents Chemother 41 (1997): 1207
  10. "Product Information. Fortovase (saquinavir)." Roche Laboratories PROD (2001):
  11. Eadie MJ "Clinically significant drug interactions with agents specific for migraine attacks." Cns Drugs 15 (2001): 105-18
  12. Spiegel M, Schmidauer C, Kampfl A, Sarcletti M, Poewe W "Cerebral ergotism under treatment with ergotamine and ritonavir." Neurology 57 (2001): 743-4
  13. Mangum EM, Graham KK "Lopinavir-Ritonavir: a new protease inhibitor." Pharmacotherapy 21 (2001): 1352-63
  14. Vila A, Mykietiuk A, Bonvehi P, Temporiti E, Uruena A, Herrera F "Clinical ergotism induced by ritonavir." Scand J Infect Dis 33 (2001): 788-9
  15. Montero A, Giovannoni AG, Tvrde PL "Leg ischemia in a patient receiving ritonavir and ergotamine." Ann Intern Med 130 (1999): 329
  16. Liaudet L "Severe ergotism associated with interaction between ritonavir and ergotamine." BMJ 318 (1999): 771
  17. Mortier E, Pouchet J, Vinceneux P, Lalande M "Ergotism related to interaction between nelfinavir and ergotamine." Am J Med 110 (2001): 594
  18. Blanche P, Rigolet A, Gombert B, Ginsburg C, Salmon D, Sicard D "Ergotism related to a single dose of ergotamine tartrate in an AIDS patient treated with ritonavir." Postgrad Med J 75 (1999): 546-7
  19. Baldwin ZK, Ceraldi CC "Ergotism associated with HIV antiviral protease inhibitor therapy." J Vasc Surg 37 (2003): 676-8
  20. Tribble MA, Gregg CR, Margolis DM, Amirkhan R, Smith JW "Fatal ergotism induced by an HIV protease inhibitor." Headache 42 (2002): 694-5
  21. "Product Information. Reyataz (atazanavir)." Bristol-Myers Squibb (2003):
  22. "Product Information. Lexiva (fosamprenavir)." GlaxoSmithKline (2003):
  23. "Product Information. Cafergot (caffeine-ergotamine)." Novartis Pharmaceuticals (2004):
  24. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  25. "Product Information. Prezista (darunavir)." Ortho Biotech Inc (2006):
  26. Canadian Pharmacists Association "e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink" (2006):
  27. "Product Information. Victrelis (boceprevir)." Schering-Plough Corporation (2011):
  28. "Product Information. Incivek (telaprevir)." Vertex Pharmaceuticals (2011):
  29. Srisuma S, Lavonas EJ, Wananukul W "Ergotism and factitious hypotension associated with interaction of ergotamine with CYP3A4 inhibitors." Clin Toxicol (Phila) (2014): 1-4
View all 29 references

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Major

ergotamine cobicistat

Applies to: Eperbel-S (belladonna / ergotamine / phenobarbital) and atazanavir / cobicistat

CONTRAINDICATED: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of ergot derivatives, which are primarily metabolized by the isoenzyme. The interaction has occurred in patients receiving ergotamine or dihydroergotamine with potent CYP450 3A4 inhibitors such as macrolide antibiotics and protease inhibitors. Clinical ergotism has been reported, which can lead to gangrene and myocardial infarction in severe cases. Even small, single doses of ergotamine have resulted in clinically significant interactions, occasionally resulting in surgical amputation or death.

MANAGEMENT: Given the potential for ergot toxicity characterized by peripheral vasospasm, ischemia, thrombosis, tachycardia and hypertension, concomitant use of ergot derivatives with potent CYP450 3A4 inhibitors is considered contraindicated.

References

  1. Leroy F, Asseman P, Pruvost P, Adnet P, Lacroix D, Thery C "Dihydroergotamine-erythromycin-induced ergotism." Ann Intern Med 109 (1988): 249
  2. Matthews NT, Havill JH "Ergotism with therapeutic doses of ergotamine tartrate." N Z Med J 89 (1979): 476-7
  3. Francis H, Tyndall A, Webb J "Severe vascular spasm due to erythromycin-ergotamine interaction." Clin Rheumatol 3 (1984): 243-6
  4. Hayton AC "Precipitation of acute ergotism by triacetyloleandomycin." N Z Med J 69 (1969): 42
  5. "Product Information. D.H.E. 45 (dihydroergotamine)." Sandoz Pharmaceuticals Corporation PROD (2002):
  6. Ghali R, De Lean J, Douville Y, Noel HP, Labbe R "Erythromycin-associated ergotamine intoxication: arteriographic and electrophysiologic analysis of a rare cause of severe ischemia of the lower extremities and associated ischemic neuropathy." Ann Vasc Surg 7 (1993): 291-6
  7. Horowitz RS, Dart RC, Gomez HF "Clinical ergotism with lingual ischemia induced by clarithromycin-ergotamine interaction." Arch Intern Med 156 (1996): 456-8
  8. "Product Information. Migranal (dihydroergotamine nasal)." Novartis Pharmaceuticals PROD (2001):
  9. Rosenthal E, Sala F, Chichmanian RM, Batt M, Cassuto JP "Ergotism related to concurrent administration of ergotamine tartrate and indinavir." JAMA 281 (1999): 987
  10. Liaudet L, Buclin T, Jaccard C, Eckert P "Severe ergotism associated with interaction between ritonavir and ergotamine." Br Med J 318 (1999): 771
  11. Caballero-Granado FJ, Viciana P, Cordero E, Gomez-Vera MJ, del Nozal M, Lopez-Cortes LF "Ergotism related to concurrent administration of ergotamine tartrate and ritonavir in an AIDS patient." Antimicrob Agents Chemother 41 (1997): 1207
  12. Dresser GK, Spence JD, Bailey DG "Pharmacokinetic-pharmacodynamic consequences and clinical relevance of cytochrome P450 3A4 inhibition." Clin Pharmacokinet 38 (2000): 41-57
  13. Bird PA, Sturgess AD "Clinical ergotism with severe bilateral upper limb ischaemia precipitated by an erythromycin - ergotamine drug interaction." Aust N Z J Med 30 (2000): 635-6
  14. Eadie MJ "Clinically significant drug interactions with agents specific for migraine attacks." Cns Drugs 15 (2001): 105-18
  15. Spiegel M, Schmidauer C, Kampfl A, Sarcletti M, Poewe W "Cerebral ergotism under treatment with ergotamine and ritonavir." Neurology 57 (2001): 743-4
  16. Vila A, Mykietiuk A, Bonvehi P, Temporiti E, Uruena A, Herrera F "Clinical ergotism induced by ritonavir." Scand J Infect Dis 33 (2001): 788-9
  17. Montero A, Giovannoni AG, Tvrde PL "Leg ischemia in a patient receiving ritonavir and ergotamine." Ann Intern Med 130 (1999): 329
  18. Liaudet L "Severe ergotism associated with interaction between ritonavir and ergotamine." BMJ 318 (1999): 771
  19. Mortier E, Pouchet J, Vinceneux P, Lalande M "Ergotism related to interaction between nelfinavir and ergotamine." Am J Med 110 (2001): 594
  20. Blanche P, Rigolet A, Gombert B, Ginsburg C, Salmon D, Sicard D "Ergotism related to a single dose of ergotamine tartrate in an AIDS patient treated with ritonavir." Postgrad Med J 75 (1999): 546-7
  21. Ausband SC, Goodman PE "An unusual case of clarithromycin associated ergotism." J Emerg Med 4 (2001): 411-3
  22. Tribble MA, Gregg CR, Margolis DM, Amirkhan R, Smith JW "Fatal ergotism induced by an HIV protease inhibitor." Headache 42 (2002): 694-5
  23. "Product Information. Cafergot (caffeine-ergotamine)." Novartis Pharmaceuticals (2004):
  24. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  25. "Product Information. Methergine (methylergonovine)." Novartis Pharmaceuticals (2010):
  26. Srisuma S, Lavonas EJ, Wananukul W "Ergotism and factitious hypotension associated with interaction of ergotamine with CYP3A4 inhibitors." Clin Toxicol (Phila) (2014): 1-4
View all 26 references

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Major

PHENobarbital cobicistat

Applies to: Eperbel-S (belladonna / ergotamine / phenobarbital) and atazanavir / cobicistat

CONTRAINDICATED: Coadministration with potent inducers of CYP450 3A4 may significantly decrease the plasma concentrations of cobicistat, which is primarily metabolized by the isoenzyme. In a study of 12 healthy volunteers, coadministration of the potent CYP450 3A4 inducer carbamazepine (200 mg twice daily) with cobicistat-elvitegravir (150 mg-150 mg once a day) reduced the cobicistat systemic exposure (AUC) and peak plasma concentration (Cmax) by 84% and 72%, respectively, and the elvitegravir AUC and Cmax by 69% and 45%, respectively. In addition, the AUC and Cmax of carbamazepine increased by 43% and 40%, respectively, due to inhibition of the CYP450 3A4-mediated metabolism by cobicistat.

MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic drug levels, concomitant use of antiretroviral regimens containing cobicistat with potent CYP450 3A4 inducers is considered contraindicated.

References

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  2. Cerner Multum, Inc. "Australian Product Information." O 0
  3. "Product Information. Stribild (cobicistat/elvitegravir/emtricitabine/tenofov)." Gilead Sciences (2012):
  4. "Product Information. Vitekta (elvitegravir)." Gilead Sciences (2014):
  5. "Product Information. Tybost (cobicistat)." Gilead Sciences (2014):
View all 5 references

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Moderate

ergotamine PHENobarbital

Applies to: Eperbel-S (belladonna / ergotamine / phenobarbital) and Eperbel-S (belladonna / ergotamine / phenobarbital)

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of ergot alkaloids, which are substrates of the isoenzyme.

MANAGEMENT: The potential for diminished pharmacologic effects of ergot alkaloids should be considered during coadministration with CYP450 3A4 inducers. Alternative treatments may be required if an interaction is suspected.

References

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  2. Cerner Multum, Inc. "Australian Product Information." O 0
  3. "Product Information. Methergine (methylergonovine)." Novartis Pharmaceuticals (2010):

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Moderate

PHENobarbital atazanavir

Applies to: Eperbel-S (belladonna / ergotamine / phenobarbital) and atazanavir / cobicistat

MONITOR: Coadministration with drugs that are inducers of CYP450 3A4 may decrease the plasma concentrations of protease inhibitors (PIs), which are primarily metabolized by the isoenzyme.

MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic antiretroviral drug levels, protease inhibitors should be used cautiously with agents that induce CYP450 3A4, particularly if only one PI is used in the antiretroviral regimen. Coadministration of atazanavir without ritonavir and carbamazepine, phenobarbital, or phenytoin is not recommended. Antiretroviral response should be monitored more closely whenever a CYP450 3A4 inducer is added to or withdrawn from therapy, and the antiretroviral regimen adjusted as necessary.

References

  1. "Product Information. Invirase (saquinavir)." Roche Laboratories PROD (2001):
  2. "Product Information. Crixivan (indinavir)." Merck & Co., Inc PROD (2001):
  3. "Product Information. Viracept (nelfinavir)." Agouron Pharma Inc PROD (2001):
  4. Brooks J, Daily J, Schwamm L "Protease inhibitors and anticonvulsants." AIDS Clin Care 9 (1997): 87,90
  5. Barry M, Gibbons S, Back D, Mulcahy F "Protease inhibitors in patients with HIV disease. Clinically important pharmacokinetic considerations." Clin Pharmacokinet 32 (1997): 194-209
  6. "Product Information. Agenerase (amprenavir)." Glaxo Wellcome PROD (2001):
  7. Acosta EP, Henry K, Baken L, Page LM, Fletcher CV "Indinavir concentrations and antiviral effect." Pharmacotherapy 19 (1999): 708-12
  8. Sommadossi JP "HIV protease inhibitors: pharmacologic and metabolic distinctions." AIDS 13 (1999): s29-40
  9. Hugen PWH, Burger DM, Brinkman K, terHofstede HJM, Schuurman R, Koopmans PP, Hekster YA "Carbamazepine-indinavir interaction causes antiretroviral therapy failure." Ann Pharmacother 34 (2000): 465-70
  10. Durant J, Clevenbergh P, Garraffo R, Halfon P, Icard S, DelGiudice P, Montagne N, Schapiro JM, Dellamonica P "Importance of protease inhibitor plasma levels in HIV-infected patients treated with genotypic-guided therapy: pharmacological data from the Viradapt Study." Aids 14 (2000): 1333-9
  11. "Product Information. Fortovase (saquinavir)." Roche Laboratories PROD (2001):
  12. "Product Information. Reyataz (atazanavir)." Bristol-Myers Squibb (2003):
  13. "Product Information. Lexiva (fosamprenavir)." GlaxoSmithKline (2003):
  14. Liedtke MD, Lockhart SM, Rathbun RC "Anticonvulsant and antiretroviral interactions." Ann Pharmacother 38 (2004): 482-9
  15. "Product Information. Aptivus (tipranavir)." Boehringer-Ingelheim (2005):
  16. "Product Information. Prezista (darunavir)." Ortho Biotech Inc (2006):
  17. Canadian Pharmacists Association "e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink" (2006):
View all 17 references

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Drug and food interactions

Major

PHENobarbital food

Applies to: Eperbel-S (belladonna / ergotamine / phenobarbital)

GENERALLY AVOID: Concurrent acute use of barbiturates and ethanol may result in additive CNS effects, including impaired coordination, sedation, and death. Tolerance of these agents may occur with chronic use. The mechanism is related to inhibition of microsomal enzymes acutely and induction of hepatic microsomal enzymes chronically.

MANAGEMENT: The combination of ethanol and barbiturates should be avoided.

References

  1. Gupta RC, Kofoed J "Toxological statistics for barbiturates, other sedatives, and tranquilizers in Ontario: a 10-year survey." Can Med Assoc J 94 (1966): 863-5
  2. Misra PS, Lefevre A, Ishii H, Rubin E, Lieber CS "Increase of ethanol, meprobamate and pentobarbital metabolism after chronic ethanol administration in man and in rats." Am J Med 51 (1971): 346-51
  3. Saario I, Linnoila M "Effect of subacute treatment with hypnotics, alone or in combination with alcohol, on psychomotor skills related to driving." Acta Pharmacol Toxicol (Copenh) 38 (1976): 382-92
  4. Stead AH, Moffat AC "Quantification of the interaction between barbiturates and alcohol and interpretation of fatal blood concentrations." Hum Toxicol 2 (1983): 5-14
  5. Seixas FA "Drug/alcohol interactions: avert potential dangers." Geriatrics 34 (1979): 89-102
View all 5 references

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Moderate

ergotamine food

Applies to: Eperbel-S (belladonna / ergotamine / phenobarbital)

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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Moderate

atazanavir food

Applies to: atazanavir / cobicistat

ADJUST DOSING INTERVAL: Administration of atazanavir with food enhances oral bioavailability and reduces pharmacokinetic variability. According to the manufacturer, administration with a light meal increased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of a single 400 mg dose of atazanavir by 57% and 70%, respectively, relative to the fasting state. Administration with a high-fat meal resulted in a mean increase of 35% in atazanavir AUC and no change in Cmax compared to fasting. The coefficient of variation of AUC and Cmax decreased by approximately one-half when given with either a light or high-fat meal compared to the fasting state.

MANAGEMENT: To ensure maximal oral absorption, atazanavir should be administered with or immediately after a meal.

References

  1. "Product Information. Reyataz (atazanavir)." Bristol-Myers Squibb (2003):

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Moderate

belladonna food

Applies to: Eperbel-S (belladonna / ergotamine / phenobarbital)

GENERALLY AVOID: Use of anticholinergic agents with alcohol may result in sufficient impairment of attention so as to render driving and operating machinery more hazardous. In addition, the potential for abuse may be increased with the combination. The mechanism of interaction is not established but may involve additive depressant effects on the central nervous system. No effect of oral propantheline or atropine on blood alcohol levels was observed in healthy volunteers when administered before ingestion of a standard ethanol load. However, one study found impairment of attention in subjects given atropine 0.5 mg or glycopyrrolate 1 mg in combination with alcohol.

MANAGEMENT: Alcohol should generally be avoided during therapy with anticholinergic agents. Patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them.

References

  1. Linnoila M "Drug effects on psychomotor skills related to driving: interaction of atropine, glycopyrrhonium and alcohol." Eur J Clin Pharmacol 6 (1973): 107-12

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Moderate

ergotamine food

Applies to: Eperbel-S (belladonna / ergotamine / phenobarbital)

MONITOR: Nicotine may cause vasoconstriction in some patients and potentiate the ischemic response to ergot alkaloids.

MANAGEMENT: Caution may be advisable when ergot alkaloids are used in combination with nicotine products. Patients should be advised to seek immediate medical attention if they experience potential symptoms of ischemia such as coldness, pallor, cyanosis, numbness, tingling, or pain in the extremities; muscle weakness; severe or worsening headache; visual disturbances; severe abdominal pain; chest pain; and shortness of breath.

References

  1. "Product Information. Migranal (dihydroergotamine nasal)." Novartis Pharmaceuticals PROD (2001):
  2. "Product Information. Cafergot (caffeine-ergotamine)." Novartis Pharmaceuticals (2004):
  3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  4. Cerner Multum, Inc. "Australian Product Information." O 0
View all 4 references

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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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