Seeley J. Yoo, Annie K. Griffith
Faculty Sponsor: Dr. Mark Smith
The H1 receptor antagonist, diphenhydramine (Benadryl), and the benzodiazepine receptor agonist, flunitrazepam (Rohypnol), have both been identified in cases of drug-facilitated sexual assault, a crime in which a victim is first rendered unconscious or incapacitated. Both drugs produce dose-dependent decreases in motor performance when administered alone, but they have not been examined in combination with one another. The purpose of the present study was to examine the interactions between diphenhydramine and flunitrazepam in an animal model of motor performance. To this end, 10 male rats were trained to walk on a rotarod apparatus rotating at 16 rpm. Following training, rats were pretreated with either saline or diphenhydramine and tested with cumulative doses of flunitrazepam. Diphenhydramine did not alter motor performance when administered alone, yielding effects similar to that observed with saline. In contrast, flunitrazepam decreased motor performance in a dose-dependent manner regardless of the pretreatment administered. Pretreatment with diphenhydramine significantly enhanced the motor-impairing effects of cumulative doses of flunitrazepam, resulting in further decrements in performance. At all doses tested, the effects of the drug combination were greater than that predicted by a simple summation of each drug’s individual effects, which is indicative of synergistic interaction. These data suggest that combined exposure to both diphenhydramine and flunitrazepam may significantly increase the risk to the victim in drug-facilitated crimes.