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Drug Interactions between fexofenadine and histamine phosphate

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

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Interactions between your drugs

Moderate

histamine phosphate fexofenadine

Applies to: histamine phosphate and fexofenadine

MONITOR: Antihistamines may suppress the patient's response to histamine phosphate. The length of suppression varies and is dependent on the patient, type of antihistamine, and the duration of antihistamine therapy. The duration of suppression may range from 24 hours with chlorpheniramine or up to several weeks with second-generation antihistamines.

MANAGEMENT: Clinicians should be aware of the potential for falsely insignificant or false-negative results when administering histamine phosphate to patients treated with antihistamines.

References

  1. "Product Information. Histatrol (histamine phosphate)." Center Laboratories (2002):

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Drug and food interactions

Moderate

fexofenadine food

Applies to: fexofenadine

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

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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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