The effects of a new benzodiazepine derivative, ID-540, on the averaged photopalpebral reflex in man.

The effects of 7-chloro-5-(2-fluorophenyl)-1-methyl-1 H, 1.4-benzodiazepin-2(3H)-one (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 or placebo were investigated in six male Japanese students in a double-blind, crossover design. The peak latencies of PPR showed a statistically significant prolongation, with maximum level at 3 h after administration, which recovered to the initial level within 4 h. The amplitude of PPR failed to show a definite response to the drug. The serum concentration of ID-540 reached a peak level 2-3 h after administration, and then decreased at 4 h. N-Desmethyl-ID-540 exhibited a slow- gradual rise in serum. The latencies of PPR were positively correlated with the serum level of ID-540 but not with the N-desmethyl-ID-540. It is concluded that the PPR test may be a useful method for predicting the clinical effects of psychotropic drugs.