Myoclonic seizures in the mouse induced by alphaxalone and related steroid anaesthetics.

The anaesthetic steroids alphaxalone. 5 beta-alphaxalone and pregnanolone each caused myoclonic jerks in mice in a dose-related manner between 4 and 16 mg kg-1 i.v. There was no loss of righting reflex at these doses. The veterinary product Saffan, which contains alphaxalone and alphadalone, also caused myoclonic jerks at 2 mg kg-1 i.v., and a loss of righting reflex at doses of 4 mg kg-1 and above. These effects appear to be unrelated to the wide spectrum of potencies at the GABAA receptor complex of the three individual steroids as potentiators of muscimol, or as attenuators of picrotoxin.