Posovolone (Co 134444), an orally active neuroactive steroid with sedative-hypnotic properties, exhibits anticonvulsant and anxiolytic-like activities, alongside ataxic effects.

In mice, the administration of Co 134444, ranging from 0.5-10 mg/kg intraperitoneally (IP, 15 min) and 1-60 mg/kg orally (PO; 30 min), is effective against pentylenetetrazol (PTZ)-induced seizures, achieving a median effective dose (ED50) of 3.3 mg/kg for IP and 9.8 mg/kg for oral administration. Similarly, Co 134444 demonstrates efficacy in protecting against maximal electroshock (MES)-induced seizures, with an ED50 of 4.8 mg/kg when administered IP and 20.6 mg/kg PO. In rats, oral administration of Co 134444 (10-40 mg/kg; PO; 30 min) effectively counters both PTZ and MES-induced seizures, with an ED50 of 23.6 mg/kg and 25.3 mg/kg, respectively.