EFFECTS OF MEFLOQUINE ALONE AND WITH ALCOHOL ON PSYCHOMOTOR AND DRIVING PERFORMANCE

Objective: To determine whether mefloquine, a quinoline antimalarial d rug, affects psychomotor and actual driving performance when given in a prophylactic regimen, alone or in combination with alcohol. Methods: Forty male and female volunteers were randomly assigned in equal numb ers to two groups, and were treated double-blind for one month with me floquine and placebo. The medication was taken in a 250 mg dose on the evenings of Days 1, 2, 3: 8, 15, 22 and 29. Testing was done on Days 4, 23 and 30, the latter after repeated doses of alcohol sufficient to sustain a blood concentration of about 0.35 mg . ml(-1) Two real driv ing tests were used to measure prolonged (1 h) road tracking and car f ollowing performance. Critical Flicker/Fusion Frequency (CFF), critica l instability tracking and body sway were also measured in the laborat ory. Results. Mefloquine caused no significant impairment in any test at any time relative to placebo. It significantly improved road tracki ng performance on Day 4. A significant interaction between prior treat ment and alcohol was found in the body sway test, as the alcohol-induc ed change was less after mefloquine than placebo. The sensitivity of t he driving test and the CFF test were shown by the significant overall effect of alcohol which did not discriminate between the two prior tr eatments. Conclusion : Mefloquine did not impair driving performance b ut rather improved it in the longer test, suggesting that the drug may possess psychostimulating properties.