The median effective dose of propofol and phenobarbital sodium for general induction was measured by up-down method

Objective To measured median effective dose(ED50) of phenobarbital sodium and the propofol by up-down method via administered intraperitoneally to SD rats.Methods 36 rats were divided into two group randomly: phenobarbital group(group PB,n=18) and propofol group(group Pr,n=18).Drugs were intraperitoneally injected to SD rats(BW 180-220g) and observed the behaviors of the rats.The loss of forepaw righting reflex(FRR) was considered as successful anesthesia induction,the recovery of forepaw righting reflex(FRR) was considered as regain consciousness.Determined the dosage with sequential change,the ED50 with formula of ED50=lg-1(ΣC/Σt) and the potency ratio on them was calculated.Results The ED50 of phenobarbital and propofol were respectively 122.415mg/kg and 59.452mg/kg.The potency ratio for phenobarbital and propofol was 0.486.Conclusion This up-down method is simple,highly selective and efficient for measuring the ED50.Phenobarbital sodium and the propofol ED50 was measured with up-down method by intraperitoneally injection.The potency ratio for pentobarbital and propofol was 0.486.