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Drug Interactions between astemizole and tovorafenib

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

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Interactions between your drugs

Moderate

astemizole tovorafenib

Applies to: astemizole and tovorafenib

MONITOR: Coadministration with tovorafenib may decrease the plasma concentrations of drugs that are substrates of CYP450 3A4. The proposed mechanism is increased clearance due to tovorafenib-mediated induction of CYP450 3A4 metabolism. According to the manufacturer, tovorafenib is predicted to decrease the peak plasma concentration (Cmax) and systemic exposure (AUC) of sensitive 3A4 substrate midazolam by at least 20%. However, data from formal clinical drug interaction studies are not available.

MANAGEMENT: Caution is recommended with the concomitant use of tovorafenib and CYP450 3A4 substrates. In particular, the manufacturer of tovorafenib advises that concomitant use with sensitive CYP450 3A4 substrates with narrow therapeutic ranges should generally be avoided. If coadministration is required, patients should be monitored carefully for potential loss of therapeutic effects.

References (1)
  1. (2024) "Product Information. Ojemda (tovorafenib)." Day One Biopharmaceuticals, Inc.

Drug and food interactions

Major

astemizole food

Applies to: astemizole

GENERALLY AVOID: Some beverages such as tonic water contain varying amounts of quinine. Coadministration of a single 430 mg dose of quinine has been shown to increase plasma concentrations of astemizole and its metabolite, desmethylastemizole. Elevated levels of these agents may cause a prolongation of the electrocardiographic QT interval and potentially fatal ventricular arrhythmias. Although pharmacokinetic data have indicated that the amounts of quinine in beverages (up to 80 mg quinine in 32 oz of tonic water) are not sufficient to produce a significant effect, the potential for an interaction exists if large amounts of tonic water are ingested. Also, grapefruit juice has been shown to inhibit CYP450 enzymes, which may lead to increased serum astemizole concentrations. The risk of life-threatening ventricular arrhythmias may be increased.

MANAGEMENT: Patients should be counseled to limit consumption of quinine-containing beverages and avoid grapefruit juice while they are taking astemizole.

References (1)
  1. (2002) "Product Information. Hismanal (astemizole)." Janssen Pharmaceuticals

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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