Complex sentence: The initial doses of premazepam given to human test subjects demonstrated similar psychological test results and showed that premazepam has similar sedative effects as compared with diazepam, although psychomotor impairments are greater with premazepam than with diazepam.
Split into simpler sentences: The initial doses of premazepam given to human test subjects demonstrated similar psychological test results to those produced by diazepam. It was also demonstrated that premazepam has similar sedative effects as compared with diazepam, although psychomotor impairments are greater with premazepam than with diazepam.