[Modeling of the bactericidal effect of spiramycin. Choice of a pharmacodynamic model].

The modelling of in vitro growth curves of Staphylococcus aureus ATCC 6538P at different pHs, of spiramycin killing curves and of the dose-effect relationship was performed. The growth curve was characterised by a Volterra-Kostitzin differential model, the main parameters of which were the bacterial growth rate constant of 0.95 +/- 0.13 h-1 and a lag-time of 0.74 +/- 0.36 h. The Zhi model used for bactericidal kinetics showed the same bacterial killing rate constant from a minimum concentration characteristic of "time-dependent" antibiotics. This differential model incorporated with pharmacokinetic models could lead to a rationale for proper dosage regimens.