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Drug Interactions between bexarotene and terfenadine

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

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Moderate

terfenadine bexarotene

Applies to: terfenadine and bexarotene

MONITOR: Coadministration with bexarotene may decrease the plasma concentrations of drugs that are primarily metabolized by CYP450 3A4. The proposed mechanism is increased clearance due to induction of CYP450 3A4 activity by bexarotene, particularly at dosages above 300 mg/m2/day. In a study of patients with non-small cell lung cancer receiving bexarotene (400 mg/m2 orally once a day) plus either paclitaxel/carboplatin or cisplatin/vinorelbine chemotherapy, treatment with atorvastatin (a CYP450 3A4 substrate) or fenofibrate was given to manage bexarotene-induced hyperlipidemia. Investigators reported that bexarotene decreased mean atorvastatin systemic exposure (dose-corrected AUC) by approximately 50%, whereas atorvastatin had no significant effect on bexarotene plasma concentrations. The AUC of paclitaxel (200 mg/m2 IV over 3 hours), a substrate of both CYP450 3A4 and 2C8, was also decreased by 19% when coadministered with bexarotene. According to the product labeling, bexarotene may decrease the plasma concentrations of another CYP450 3A4 substrate, tamoxifen, by 35%.

MANAGEMENT: Caution is advised if bexarotene is prescribed concomitantly with medications that are primarily metabolized by CYP450 3A4, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever bexarotene is added to or withdrawn from therapy.

References

  1. (2001) "Product Information. Targretin (bexarotene)." Ligand Pharmaceuticals
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  3. Wakelee HA, Takimoto CH, Lopez-Anaya A, et al. (2012) "The effect of bexarotene on atorvastatin pharmacokinetics: results from a phase I trial of bexarotene plus chemotherapy in patients with advanced non-small cell lung cancer." Cancer Chemother Pharmacol, 69, p. 563-71

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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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Moderate

bexarotene food

Applies to: bexarotene

ADJUST DOSING INTERVAL: Food may enhance the oral bioavailability of bexarotene. In one clinical study, bexarotene peak plasma concentration (Cmax) and systemic exposure (AUC) resulting from a 75 to 300 mg dose were 35% and 48% higher, respectively, when administered after a fat-containing meal relative to a glucose solution. In all clinical trials, patients were instructed to take bexarotene with or immediately following a meal.

Coadministration with inhibitors of CYP450 3A4 such as grapefruit juice may theoretically increase the plasma concentrations of bexarotene. In vitro studies suggest that bexarotene is metabolized by CYP450 3A4. However, concomitant administration with multiple doses of ketoconazole, a potent CYP450 3A4 inhibitor, did not alter bexarotene plasma concentrations, which would imply that bexarotene elimination is not substantially dependent on CYP450 3A4 metabolism in vivo.

MANAGEMENT: Because safety and efficacy data are based upon administration with food, bexarotene should be administered once daily with a meal. Patients may want to avoid consuming large amounts of grapefruit or grapefruit juice.

References

  1. (2001) "Product Information. Targretin (bexarotene)." Ligand Pharmaceuticals
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."

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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.