EFFECTS OF THE NOVEL NMDA-RECEPTOR ANTAGONIST SDZ-EAA-494 ON MEMORY AND ATTENTION IN HUMANS

Effects of the novel competitive N-methyl-D-aspartate (NMDA)-receptor antagonist SDZ EAA 494 were investigated on memory and attention in hu mans. SDZ EAA 494 was administered either as single doses at a dose ra nge of 1-50 mg, or as multiple doses over the course of 1 week at dose s of 25 mg once or twice daily. Selected cognitive functions were asse ssed at baseline, 2 and 4 h after single dose administration, and at b aseline, 2, 4 and 8 h on days 1 and 7 of multiple dose administration. The assessments included simple and complex reaction time tests to as sess attention, and verbal, non-verbal and spatial memory tests with i mmediate and late recall. Verbal and non-verbal memory test performanc e was significantly impaired at a dose level of 50 mg after single adm inistration, and of 25 mg twice daily after multiple administration, w ithout concomitant significant impairment of reaction time. Spatial me mory test performance was not significantly affected. The maximum effe ct occurred 2 h postmedication and was more pronounced after repeated administration. These results suggest that the inhibition of NMDA-rece ptors in humans may impair memory processes.