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Drug Interactions between Gleevec and pseudoephedrine / terfenadine

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

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Interactions between your drugs

Moderate

terfenadine imatinib

Applies to: pseudoephedrine / terfenadine and Gleevec (imatinib)

MONITOR: Coadministration with imatinib may increase the plasma concentrations of drugs that are substrates of CYP450 2C9, 2D6 and/or 3A4. The mechanism is decreased clearance due to inhibition of these isoenzymes by imatinib. According to the manufacturer, imatinib increased the mean peak plasma concentration (Cmax) and systemic exposure (AUC) of simvastatin, a sensitive CYP450 3A4 substrate, by 2- and 3.5-fold, respectively. Data for other substrates are limited, although human liver microsome studies indicate that imatinib is a potent competitive inhibitor of all three isoenzymes.

MANAGEMENT: Caution is advised when imatinib is used concomitantly with drugs that undergo metabolism by CYP450 2C9, 2D6 and/or 3A4, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever imatinib is added to or withdrawn from therapy.

References

  1. (2022) "Product Information. Gleevec (imatinib)." Novartis Pharmaceuticals

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Drug and food interactions

Major

terfenadine food

Applies to: pseudoephedrine / 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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Moderate

imatinib food

Applies to: Gleevec (imatinib)

GENERALLY AVOID: Coadministration of imatinib with strong CYP450 3A4 inhibitors such as grapefruit juice, may significantly increase the plasma concentrations of imatinib, a known substrate of CYP450 3A4. The proposed mechanism is inhibition of CYP450 3A4-mediated metabolism of imatinib by certain compounds present in grapefruits. 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. In a single-dose study, coadministration of imatinib with ketoconazole (a strong CYP450 3A4 inhibitor) increased imatinib peak plasma concentration (Cmax) and systemic exposure (AUC) by 26% and 40%, respectively.

MANAGEMENT: Patients treated with imatinib should preferably avoid the consumption of grapefruit or grapefruit juice. If coadministration is unavoidable, monitor for prolonged and/or increased pharmacologic effects of imatinib, including edema, hematologic toxicity and immunosuppression.

References

  1. (2022) "Product Information. Gleevec (imatinib)." Novartis Pharmaceuticals
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  3. Cerner Multum, Inc. "Australian Product Information."

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Moderate

pseudoephedrine food

Applies to: pseudoephedrine / terfenadine

MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.

MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.

References

  1. Rosenblatt JE, Lake CR, van Kammen DP, Ziegler MG, Bunney WE Jr (1979) "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res, 1, p. 45-52
  2. Cavanaugh JH, Griffith JD, Oates JA (1970) "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther, 11, p. 656
  3. (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
  4. (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
  5. (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
  6. (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
  7. (2002) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
View all 7 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

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