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Drug Interactions between astemizole and mefloquine

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

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Interactions between your drugs

Moderate

mefloquine astemizole

Applies to: mefloquine and astemizole

MONITOR: Mefloquine is a myocardial depressant and can cause ECG abnormalities. Theoretically, coadministration with other agents that can affect cardiac conduction (e.g., antiarrhythmic agents, beta blockers, calcium channel blockers, certain antihistamines, tricyclic antidepressants, phenothiazines, some neuroleptics) may result in additive effects and increased risk of ventricular arrhythmias including ventricular tachycardia and torsade de pointes. Parenteral studies in animals have shown that mefloquine possesses 20% of the antifibrillatory action of quinidine and can cause 50% of the increase in PR interval reported with quinine. ECG alterations reported with mefloquine include sinus bradycardia, sinus arrhythmia, first degree AV block, prolongation of the QTc interval, and abnormal T waves. According to mefloquine labeling, there has been one report of cardiopulmonary arrest, with full recovery, in a patient who was taking a beta blocker (propranolol).

MANAGEMENT: Caution and clinical monitoring are recommended if mefloquine is used in combination with other drugs that can prolong the QT interval or otherwise affect cardiac conduction. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes or other arrhythmia such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope.

References

  1. (2021) "Product Information. Mefloquine Hydrochloride (mefloquine)." Hikma USA (formerly West-Ward Pharmaceutical Corporation)
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  3. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink
  4. Cerner Multum, Inc. "Australian Product Information."
View all 4 references

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

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Moderate

mefloquine food

Applies to: mefloquine

ADJUST DOSING INTERVAL: Food enhances the oral absorption and bioavailability of mefloquine. The proposed mechanism is increased drug solubility in the presence of food. In 20 healthy volunteers, administration of a single 750 mg oral dose of mefloquine 30 minutes following a high-fat meal increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of mefloquine by 73% and 40%, respectively, compared to administration in the fasting state. The Cmax and AUC of the carboxylic acid metabolite were also increased by 35% and 33%, respectively, compared to fasting. In addition, the time to reach peak plasma concentration (Tmax) of mefloquine was significantly shorter after food intake (17 hours) than in the fasting state (36 hours). There was no difference in the elimination half-life of mefloquine and metabolite, or the Tmax for the metabolite.

MANAGEMENT: To ensure maximal oral absorption, mefloquine should be administered immediately after a meal with at least 8 ounces of water.

References

  1. (2021) "Product Information. Mefloquine Hydrochloride (mefloquine)." Hikma USA (formerly West-Ward Pharmaceutical Corporation)
  2. Schmidt LE, Dalhoff K (2002) "Food-drug interactions." Drugs, 62, p. 1481-502

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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.

See also

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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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