Fig. 2. Examples of log-linear serum  R- and  S- thiopental and  R- and  S- pentobarbital serum concentration–time curves shown for 5 patients. Note that the time scales are not uniform among the examples. The arrow indicates the time of completion of a thiopental infusion. □=  R- thiopental, o =  S- thiopental, +=  R- pentobarbital, x =  S- pentobarbital. Lines are the non-linear model fits to data:---=  R- thiopental, –=  S- thiopental.