The appearance and disappearance profile of plasma CPK in rabbits after intramuscular administration of 25% (w/v) of sulpyrine injection was demonstrated with seven rabbits. The profiles in five rabbits showed a biphasic pattem and could be fitted to an one-compartment open model whereas the remainder showed an erratic pattern. The mean rate constant of appearance (Kap) and disappearance (Kap) of CPK after sulpyrine injection were estimated to be 0.14 +- 0.047 (mean +- S.D.) and 0.062 +- 0.015 h-1.The regression equations obtained by the weighted damping Gauss-Newton method were presented.By using the estimation of 95% confidence intervals, Kap can be derived from the sum of Kdp and β (overall elimination rate constant from in bolus experiment).The result provides an approximate estimation for the Kap in the case ot erratic profile.
