Neuroactive steroids represent potential antiepileptic drugs. We tested a newly synthesized analogue of allopregnanolone 3α- hydroxy-21ξ,22-oxido-21-homo-5α-pregnan-20-on (HOHP) against two types of pentylenetetrazol-induced seizures (100 mg/kg s.c.) in 12- and 25-day-old rats. Ganaxolone, a neuroactive steroid in clinical trials, served as a reference drug. Pretreatment with either steroid suppressed generalized tonicclonic seizures in both age groups, their efficacy was comparable. HOHP as well as ganaxolone were more active in 12- than in 25-day-old rats (effective doses were 40 and 60 mg/kg, respectively). Minimal clonic seizures, which can be elicited only in 25-day-old rats, were not influenced by any drug. Very short duration of anticonvulsant action of HPOP demonstrated in 12-day-old animals indicates that this drug might be used only in acute treatment in epileptology., P. Mareš, H. Kubová, A. Kasal., and Obsahuje bibliografii a bibliografické odkazy