Drug Interaction Report

GENERALLY AVOID: Intrathecal administration of iodinated contrast media may induce seizures. Although clinical data are generally lacking, there may be a theoretical risk of increased seizure potential when used with selective serotonin reuptake inhibitors (SSRI antidepressants or anorectics), monoamine oxidase inhibitors, neuroleptic agents, central nervous system stimulants, opioids, tricyclic antidepressants, other tricyclic compounds (e.g., cyclobenzaprine, phenothiazines), and/or any substance that can reduce the seizure threshold (e.g., carbapenems, cholinergic agents, fluoroquinolones, interferons, chloroquine, mefloquine, lindane, theophylline). These agents are often individually epileptogenic and may have additive effects when combined.

MANAGEMENT: Drugs that can lower the seizure threshold should preferably be withheld for at least 48 hours prior to and 24 hours following intrathecal administration of iodinated contrast media, provided that temporary interruption of therapy does not pose an undue risk to the patient. Otherwise, close monitoring is advised during and after contrast administration. The manufacturers typically recommend avoiding concomitant administration of phenothiazines (including those used for their antihistamine properties), monoamine oxidase inhibitors, tricyclic antidepressants, central nervous system stimulants, and psychoactive drugs.

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.