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Drug Interactions between Allegra-D 24 Hour Allergy & Congestion and voriconazole

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

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Interactions between your drugs

Minor

fexofenadine voriconazole

Applies to: Allegra-D 24 Hour Allergy & Congestion (fexofenadine / pseudoephedrine) and voriconazole

Coadministration with ketoconazole has been shown to significantly increase the oral bioavailability of fexofenadine. The proposed mechanism is ketoconazole inhibition of the intestinal efflux of fexofenadine via P-glycoprotein transporter. In 24 healthy volunteers, coadministration of fexofenadine 120 mg twice a day and ketoconazole 400 mg once a day resulted in a 135% and 164% increase in the steady-state fexofenadine peak plasma concentration (Cmax) and systemic exposure (AUC), respectively, compared to administration of fexofenadine alone. However, no increase in adverse effects or QTc interval were noted. No studies have been performed using other azole antifungal agents, but similar results are possible given their similarities to ketoconazole. Fexofenadine had no effect on the pharmacokinetics of ketoconazole.

References

  1. (2001) "Product Information. Allegra (fexofenadine)." Hoechst Marion Roussel
  2. (2001) "Product Information. Allegra-D (fexofenadine-pseudoephedrine)." Chattem Consumer Products

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Drug and food interactions

Moderate

fexofenadine food

Applies to: Allegra-D 24 Hour Allergy & Congestion (fexofenadine / pseudoephedrine)

GENERALLY AVOID: Coadministration with large amounts of certain fruit juices, including grapefruit, orange and apple, may decrease the oral bioavailability of fexofenadine. The proposed mechanism is inhibition of drug efflux via intestinal organic anion transporting polypeptides (e.g., P-glycoprotein), of which fexofenadine is a substrate. In a five-way crossover study with 10 healthy volunteers, 1/4-strength grapefruit juice, grapefruit juice, orange juice and apple juice (300 mL with drug administration and 150 mL every 1/2 hour for up to 3 hours, total volume 1.2 L) reduced the mean area under the plasma concentration-time curve (AUC) of a 120 mg dose of fexofenadine by 23%, 67%, 72% and 77%, respectively, compared to water. Mean peak plasma concentration (Cmax) was similarly affected. The clinical significance of these changes is unknown. However, results from studies using histamine-induced skin wheals and flares found that the size of wheal and flare was significantly larger when fexofenadine was administered with either grapefruit or orange juices compared to water.

MANAGEMENT: To maximize plasma levels and therapeutic effects, fexofenadine should be taken with water. In addition, patients should refrain from consuming large amounts of grapefruit, orange, or apple juice.

References

  1. Bailey DG, Dresser GK, Munoz C, Freemar DJ, Kim RB (2001) "Reduction of fexofenadine bioavailability by fruit juices." Clin Pharmacol Ther, 69, PI-82
  2. Dresser GK, Bailey DG, Leake BF, et al. (2002) "Fruit juices inhibit organic anion transporting polypeptide-mediated drug uptake to decrease the oral availability of fexofenadine." Clin Pharmacol Ther, 71, p. 11-20

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Moderate

voriconazole food

Applies to: voriconazole

ADJUST DOSING INTERVAL: Food reduces the oral absorption and bioavailability of voriconazole. According to the product labeling, administration of multiple doses of voriconazole with high-fat meals decreased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) by 34% and 24%, respectively, when the drug is administered as a tablet, and by 58% and 37%, respectively, when administered as the oral suspension.

MANAGEMENT: To ensure maximal oral absorption, voriconazole tablets and oral suspension should be taken at least one hour before or after a meal.

References

  1. (2002) "Product Information. VFEND (voriconazole)." Pfizer U.S. Pharmaceuticals
  2. Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT (2009) "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm, 66, p. 1438-67

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Moderate

pseudoephedrine food

Applies to: Allegra-D 24 Hour Allergy & Congestion (fexofenadine / pseudoephedrine)

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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