Neuropharmacological actions of labetalol.

Labetalol, an alpha- and beta- adrenoceptor antagonist was investigated for its central nervous system effects in rats and mice. A marked reduction in the spontaneous motor activity with no concomittant muscle weakness was produced. The drug caused closure of eyelids in rats. Labetalol caused hypothermia and prolonged the pentobarbitone-induced hyposis. In animals trained for conditioned avoidance response the drug blocked the SCR in all the animals and CAR in a few number of animals. The drug did not protect the animals against electroshock convulsions. From the results it appears that labetalol is a central nervous system depressant.