Serious adverse events of mefloquine in relation to blood level and gender

Mefloquine is widely used for prophylaxis in areas with chloroquine-resista nt falciparum malaria. As the use of mefloquine has increased, so have the reports on its adverse effects. We sought to evaluate the possible associat ion between serum levels of mefloquine and serious side effects caused by t his drug by means of a case-control design study. The study population incl uded 17 patients who presented to emergency rooms or travel clinics with sy mptoms suggesting serious adverse effects of mefloquine and 28 controls (he althy people, still taking mefloquine after travel). The mean age of the pa tients and the controls was 31.5 +/- 11.6 years and 34 +/- 12.2 years, resp ectively. The percentage of women among the patients was higher than in the control population (76% versus 40%, respectively; P = 0.03). Most of the c omplaints were related to the central nervous system (13 of 17); 5 patients interrupted their trip and 2 others were hospitalized. No difference in th e level of mefloquine in the blood was found between the patients and the c ontrol groups. Also, no significant difference was found between mefloquine levels in the blood of men and women. These results suggest that blood lev els of mefloquine do not correlate with its severe adverse events. Women te nded to be more susceptible than men, despite having similar blood levels o f the drug.