Dosage assessment of valnemulin in pigs based on population pharmacokinetic and Monte Carlo simulation

To estimate the valnemulin pharmacokinetic profile in a swine population and to assess a dosage regimen for increasing the likelihood of optimization. This study was, respectively, performed in 22 sows culled by p.o. administration and in 80 growing‐finishing pigs by i.v. administration at a single dose of 10 mg/kg to develop a population pharmacokinetic model and Monte Carlo simulation. The relationships among the plasma concentration, dose, and time of valnemulin in pigs were illustrated as C i , v  =  X 0 (8.4191 × 10 ‐4 × e −0.2371 t + 1.2788 × 10 −5 × e −0.0069 t ) after i.v. and C p . o = X 0 (−8.4964 × 10 −4 × e −0.5840 t + 8.4195 × e −0.2371 t + 7.6869 × 10 −6  ×  e −0.0069 t ) after p.o. Monte Carlo simulation showed that T > MIC was more than 24 h when a single daily dosage at 13.5 mg/kg BW in pigs was administrated by p.o., and MIC was 0.031 mg/L. It was concluded that the current dosage regimen at 10–12 mg/kg BW led to valnemulin underexposure if the MIC was more than 0.031 mg/L and could increase the risk of treatment failure and/or drug resistance.