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Drug Interactions between Omeclamox-Pak and terfenadine

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

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Interactions between your drugs

Major

clarithromycin terfenadine

Applies to: Omeclamox-Pak (amoxicillin / clarithromycin / omeprazole) and terfenadine

CONTRAINDICATED: Coadministration with the ketolide, telithromycin, as well as certain macrolide antibiotics may significantly increase the plasma concentrations of astemizole and terfenadine. The mechanism is inhibition of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of astemizole and terfenadine. High plasma levels of these agents have been associated with prolongation of the QT interval on the ECG; ventricular arrhythmias including ventricular tachycardia, ventricular fibrillation, and torsade de pointes; cardiac arrest; and sudden death. Macrolides that may significantly inhibit CYP450 3A4 include clarithromycin, erythromycin, and troleandomycin. Azithromycin and dirithromycin are generally believed to have little, if any, effect on CYP450 3A4. In a study of 9 healthy volunteers, erythromycin (500 mg every 8 hours for 7 days) increased the mean steady-state peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of the pharmacologically active metabolite of terfenadine (60 mg twice a day) by 107% and 170%, respectively, compared to administration of terfenadine alone. Three of the subjects also had accumulation of unmetabolized terfenadine. Electrocardiographic data revealed changes in the QT interval in a subset of subjects who demonstrated drug accumulation.

MANAGEMENT: Given the potential for serious and life-threatening adverse cardiac events associated with increased plasma levels of astemizole and terfenadine, the use of these agents with clarithromycin, erythromycin, troleandomycin, or telithromycin is considered contraindicated. Loratadine, cetirizine, or fexofenadine may be safer alternatives during therapy with telithromycin or macrolides. Depending on organism susceptibility, azithromycin and dirithromycin may be appropriate alternatives during therapy with astemizole or terfenadine.

References

  1. Honig PK, Woosley RL, Zamani K, Conner DP, Cantilena LR Jr (1992) "Changes in the pharmacokinetics and electrocardiographic pharmacodynamics of terfenadine with concomitant administration of erythromycin." Clin Pharmacol Ther, 52, p. 231-8
  2. Cortese LM, Bjornson DC (1992) "Potential interaction between terfenadine and macrolide antibiotics." Clin Pharm, 11, p. 675
  3. Kemp JP (1992) "Decreased antihistamine metabolism." Ann Allergy, 69, p. 533
  4. (2002) "Product Information. Hismanal (astemizole)." Janssen Pharmaceuticals
  5. Biglin KE, Faraon MS, Constance TD, Lieh-Lai M (1994) "Drug-induced torsades de pointes: a possible interaction of terfenadine and erythromycin." Ann Pharmacother, 28, p. 282
  6. Paris DG, Parente TF, Bruschetta HR, Guzman E, Niarchos AP (1994) "Torsades-de-pointes induced by erythromycin and terfenadine." Am J Emerg Med, 12, p. 636-8
  7. Amsden GW (1995) "Macrolides versus azalides: a drug interaction update." Ann Pharmacother, 29, p. 906-17
  8. Brannan MD, Reidenberg P, Radwanski E, et al. (1995) "Loratadine administered concomitantly with erythromycin: pharmacokinetic and electrocardiographic evaluations." Clin Pharmacol Ther, 58, p. 269-78
  9. Harris S, Hilligoss DM, Colangelo PM, Eller M, Okerholm R (1995) "Azithromycin and terfenadine: lack of drug interaction." Clin Pharmacol Ther, 58, p. 310-5
  10. Hsieh MH, Chen SA, Chiang CE, et al. (1996) "Drug-induced torsades de pointes in one patient with congenital long QT syndrome." Int J Cardiol, 54, p. 85-8
  11. Nahata M (1996) "Drug interactions with azithromycin and the macrolides: an overview." J Antimicrob Chemother, 37 ( Suppl, p. 133-42
  12. Ament PW, Paterson A (1997) "Drug interactions with the nonsedating antihistamines." Am Fam Physician, 56, p. 223
  13. Jurima-Romet M, Crawford K, Cyr T, Inaba T (1994) "Terfenadine metabolism in human liver. In vitro inhibition by macrolide antibiotics and azole antifungals." Drug Metab Dispos, 22, p. 849-57
  14. European Agency for the Evaluation of Medicinal Products. Committee for Proprietary Medicinal Products (2004) European Public Assessment Report Ketek (telithromycin) (Rev. 2) http:www.emea.eu.int/humandocs/Humans/EPAR/Ketek/Ketek.htm
View all 14 references

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Minor

amoxicillin clarithromycin

Applies to: Omeclamox-Pak (amoxicillin / clarithromycin / omeprazole) and Omeclamox-Pak (amoxicillin / clarithromycin / omeprazole)

Although some in vitro data indicate synergism between macrolide antibiotics and penicillins, other in vitro data indicate antagonism. When these drugs are given together, neither has predictable therapeutic efficacy. Data are available for erythromycin, although theoretically this interaction could occur with any macrolide. Except for monitoring of the effectiveness of antibiotic therapy, no special precautions appear to be necessary.

References

  1. Strom J (1961) "Penicillin and erythromycin singly and in combination in scarlatina therapy and the interference between them." Antibiot Chemother, 11, p. 694-7
  2. Cohn JR, Jungkind DL, Baker JS (1980) "In vitro antagonism by erythromycin of the bactericidal action of antimicrobial agents against common respiratory pathogens." Antimicrob Agents Chemother, 18, p. 872-6
  3. Penn RL, Ward TT, Steigbigel RT (1982) "Effects of erythromycin in combination with penicillin, ampicillin, or gentamicin on the growth of listeria monocytogenes." Antimicrob Agents Chemother, 22, p. 289-94

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Minor

clarithromycin omeprazole

Applies to: Omeclamox-Pak (amoxicillin / clarithromycin / omeprazole) and Omeclamox-Pak (amoxicillin / clarithromycin / omeprazole)

Clarithromycin may increase and prolong the omeprazole plasma concentration. The mechanism may be related to clarithromycin inhibition of hepatic cytochrome P450 enzymes responsible for omeprazole metabolism. Coadministration of omeprazole may result in an increase in clarithromycin and 14-(R)-hydroxyclarithromycin plasma concentrations. These increases may be due to the effect of omeprazole on gastric pH.

References

  1. Zhou Q, Yamamoto I, Fukuda T, Ohno M, Sumida A, Azuma J (1999) "CYP2C19 genotypes and omeprazole metabolism after single and repeated dosing when combined with clarithromycin." Eur J Clin Pharmacol, 55, p. 43-7
  2. Gustavson LE, Kaiser JF, Edmonds AL, Locke CS, DeBartolo ML, Schneck DW (1995) "Effect of omeprazole on concentrations of clarithromycin in plasma and gastric tissue at steady state." Antimicrob Agents Chemother, 39, p. 2078-83
  3. Furuta T, Ohashi K, Kobayashi K, Iida I, Yoshida H, Shirai N, Takashima M, Kosuge K, Hanai H, Chiba K, Ishizaki T, Kaneko E (1999) "Effects of clarithromycin on the metabolism of omeprazole in relation to CYP2C19 genotype status in humans." Clin Pharmacol Ther, 66, p. 265-74

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Drug and food interactions

Major

terfenadine food

Applies to: terfenadine

CONTRAINDICATED: The consumption of grapefruit juice has been associated with significantly increased plasma concentrations of terfenadine. The mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. Terfenadine in high serum levels has been associated with prolongation of the QT interval and development of torsade de pointes, a potentially fatal ventricular arrhythmia.

MANAGEMENT: Due to the risk of cardiotoxicity, patients receiving the drug should be advised to avoid consumption of grapefruit products. Loratadine, cetirizine, and fexofenadine may be safer alternatives in patients who may have trouble adhering to the dietary restriction.

References

  1. Honig PK, Woosley RL, Zamani K, Conner DP, Cantilena LR Jr (1992) "Changes in the pharmacokinetics and electrocardiographic pharmacodynamics of terfenadine with concomitant administration of erythromycin." Clin Pharmacol Ther, 52, p. 231-8
  2. Zimmermann M, Duruz H, Guinand O, et al. (1992) "Torsades de Pointes after treatment with terfenadine and ketoconazole." Eur Heart J, 13, p. 1002-3
  3. Mathews DR, McNutt B, Okerholm R, et al. (1991) "Torsades de pointes occurring in association with terfenadine use." JAMA, 266, p. 2375-6
  4. Monahan BP, Ferguson CL, Killeavy ES, et al. (1990) "Torsades de pointes occurring in association with terfenadine use." JAMA, 264, p. 2788-90
  5. Honig PK, Wortham DC, Zamani K, et al. (1993) "Terfenadine-ketoconazole interaction: pharmacokinetic and electrocardiographic consequences." JAMA, 269, p. 1513-8
  6. Pohjola-Sintonen S, Viitasalo M, Toivonene L, Neuvonen P (1993) "Torsades de pointes after terfenadine-itraconazole interaction." BMJ, 306, p. 186
  7. Cortese LM, Bjornson DC (1992) "Potential interaction between terfenadine and macrolide antibiotics." Clin Pharm, 11, p. 675
  8. Paris DG, Parente TF, Bruschetta HR, Guzman E, Niarchos AP (1994) "Torsades-de-pointes induced by erythromycin and terfenadine." Am J Emerg Med, 12, p. 636-8
  9. Zechnich AD, Haxby DG (1996) "Drug interactions associated with terfenadine and related nonsedating antihistamines." West J Med, 164, p. 68-9
  10. Honig PK, Wortham DC, Lazarev A, Cantilena LR (1996) "Grapefruit juice alters the systemic bioavailability and cardiac repolarization of terfenadine in poor metabolizers of terfenadine." J Clin Pharmacol, 36, p. 345-51
  11. Woosley RL (1996) "Cardiac actions of antihistamines." Annu Rev Pharmacol Toxicol, 36, p. 233-52
  12. Benton RE, Honig PK, Zamani K, Cantilena LR, Woosley RL (1996) "Grapefruit juice alters terfenadine pharmacokinetics resulting in prolongation of repolarization on the electrocardiogram." Clin Pharmacol Ther, 59, p. 383-8
  13. Hsieh MH, Chen SA, Chiang CE, et al. (1996) "Drug-induced torsades de pointes in one patient with congenital long QT syndrome." Int J Cardiol, 54, p. 85-8
  14. Clifford CP, Adams DA, Murray S, Taylor GW, Wilkins MR, Boobis AR, Davies DS (1996) "Pharmacokinetic and cardiac effects of terfenadine after inhibition of its metabolism by grapefruit juice." Br J Clin Pharmacol, 42, p662
  15. Rau SE, Bend JR, Arnold JMO, Tran LT, Spence JD, Bailey DG (1997) "Grapefruit juice terfenadine single-dose interaction: Magnitude, mechanism, and relevance." Clin Pharmacol Ther, 61, p. 401-9
  16. Bailey DG, Malcolm J, Arnold O, Spence JD (1998) "Grapefruit juice-drug interactions." Br J Clin Pharmacol, 46, p. 101-10
  17. Bailey DG, Dresser GR, Kreeft JH, Munoz C, Freeman DJ, Bend JR (2000) "Grapefruit-felodipine interaction: Effect of unprocessed fruit and probable active ingredients." Clin Pharmacol Ther, 68, p. 468-77
View all 17 references

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Minor

clarithromycin food

Applies to: Omeclamox-Pak (amoxicillin / clarithromycin / omeprazole)

Grapefruit juice may delay the gastrointestinal absorption of clarithromycin but does not appear to affect the overall extent of absorption or inhibit the metabolism of clarithromycin. The mechanism of interaction is unknown but may be related to competition for intestinal CYP450 3A4 and/or absorptive sites. In an open-label, randomized, crossover study consisting of 12 healthy subjects, coadministration with grapefruit juice increased the time to reach peak plasma concentration (Tmax) of both clarithromycin and 14-hydroxyclarithromycin (the active metabolite) by 80% and 104%, respectively, compared to water. Other pharmacokinetic parameters were not significantly altered. This interaction is unlikely to be of clinical significance.

References

  1. Cheng KL, Nafziger AN, Peloquin CA, Amsden GW (1998) "Effect of grapefruit juice on clarithromycin pharmacokinetics." Antimicrob Agents Chemother, 42, p. 927-9

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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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