Selective effects of zolpidem on human memory functions

Zolpidem is an imidazopyridine hypnotic with preferential binding affinity for the omega(1)-benzodiazepine (BZD) receptor. The present double-blind, p lacebo-controlled study evaluated the effects of orally administered zolpid em (15 mg/70kg) on specific memory functions in 16 healthy volunteers using a battery of word and picture memory tasks. Relative to placebo, zolpidem significantly impaired memory for material presented after drug administrat ion when memory was assessed directly by referring subjects back to the pri or study episode (explicit memory: recall and recognition) but not when mem ory was assessed indirectly by evaluating subjects' ability to identify deg raded versions of studied stimuli (implicit memory: fragment completion). Z olpidem did not impair explicit memory for material presented before drug a dministration or memory for previously acquired knowledge (semantic memory: categorization). There was evidence suggesting that zolpidem enhanced expl icit and implicit memory for material presented before drug administration and that zolpidem produced a specific deficit in the acquisition of context ual information about material presented after drug administration. Despite zolpidem's unique pharmacological profile, the observed selectivity of zol pidem's memory-impairing effects for particular functions appears qualitati vely similar to the selectivity observed with classic BZDs in previous stud ies.