Selected Antimalarials/Strong CYP3A4 Inducers; Selected Barbiturates, Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

When these two medicines are taken together, your body may process mefloquine, quinidine, or quinine more quickly.

What might happen:

Your blood levels of quinidine may decrease and cause a fast or irregular heartbeat.Mefloquine and quinine may not work as well for treating malaria.

What you should do about this interaction:

Make sure your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. If you are taking quinidine, let your doctor know if you experience a fast or irregular heartbeat. It may be necessary to measure your blood levels of quinidine more often. Your doctor may need to adjust the dose. Medicines used to treat seizures and other conditions may make this interaction worse.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

  • 1.Ahmad D, Mathur P, Ahuja S, Henderson R, Carruthers G. Rifampicin-quinidine interaction. Br J Dis Chest 1979 Oct;73(4):409-11.
  • 2.Twum-Barima Y, Carruthers SG. Quinidine-rifampin interaction. N Engl J Med 1981 Jun 11;304(24):1466-9.
  • 3.Bussey HI, Merritt GJ, Hill EG. The influence of rifampin on quinidine and digoxin. Arch Intern Med 1984 May;144(5):1021-3.
  • 4.Schwartz A, Brown JR. Quinidine-rifampin interaction. Am Heart J 1984 Apr; 107(4):789-90.
  • 5.Bussey HI, Farringer J, Merritt GJ. Influence of rifampin (R) on quinidine (Q) and digoxin (D). Drug Intell Clin Pharm 1983;17(6):436.
  • 6.Qualaquin (quinine sulfate) US prescribing information. Sun Pharmaceutical Industries, Inc. August, 2019.
  • 7.Pukrittayakamee S, Prakongpan S, Wanwimolruk S, Clemens R, Looareesuwan S, White NJ. Adverse effect of rifampin on quinine efficacy in uncomplicated falciparum malaria. Antimicrob Agents Chemother 2003 May;47(5):1509-13.
  • 8.Ridtitid W, Wongnawa M, Mahatthanatrakul W, Chaipol P, Sunbhanich M. Effect of rifampin on plasma concentrations of mefloquine in healthy volunteers. J Pharm Pharmacol 2000 Oct;52(10):1265-9.
  • 9.Lariam (mefloquine hydrochloride) US prescribing information. Roche Pharmaceuticals August, 2009.
  • 10.This information is based on or an extract from the UW Metabolism and Transport Drug Interaction Database (DIDB) Platform, Copyright University of Washington 1999-2019..

Selected from data included with permission and copyrighted by First Databank, Inc. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, except as may be authorized by the applicable terms of use.

CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.