A new expression of pharmacological activity, ET63

We studied the response time of drugs in relation to the feedback mechanism in animals. The time from drug administration to onset of loss and recovery of righting reflex or death by hexobarbital in mice were measured at several dose levels and it was demonstrate that in every case the time (t)- response rate (R) function could be expressed as: (formula: see text) These parameters could be obtain by use of only a small number of animals at every dose level. The result suggests that the pharmacological activity of not only pure drugs but also of commercial chemicals with fixed standard of purity and concentrations may be expressed by the parameter t63 transposed as ET63. t63: time when cummulative response rate reaches 63%. t1: latency.