Effects of ID-540 on averaged photopalpebral reflex in man

Effects of ID-540, a recently introduced benzodiazepine derivative, on the averaged photopalpebral reflex (PPR), subjective symptoms and serum levels of ID-540 and its principal metabolite, N-desmethyl-ID-540 following an oral dose of 0.5 mg were investigated in 4 healthy male Japanese students in their early twenties. Both the latencies of PPR, P1 and P2 latency, showed a prolongation and maximum level at 2-2.5 hours after administration and tended to decline thereafter to control levels. The serum concentration of ID-540 showed a peak level at 2 hours after dosing, then showed a decline at 4 hours. The N-desmethyl-ID-540 exhibited a slow, gradual rise in the serum over the first 4 hours and there was a tendency toward a continued rise even at 24 hours. These parameters were of striking resemblance in the time-course of changes after oral dosing. Thus the PPR test may be a useful means of determining the clinical effects of anxiolytic agents. ID-540 appears to be an agent with remarkable anxiolytic effects.