Pharmacokinetic and pharmacodynamic testing of marbofloxacin administered as a single injection for the treatment of bovine respiratory disease

Valle, M., Schneider, M., Galland, D., Giboin, H., Woehrle, F. Pharmacokinetic and pharmacodynamic testing of marbofloxacin administered as a single injection for the treatment of bovine respiratory disease. J. vet. Pharmacol. Therap. 35, 519528. New approaches in Pharmacokinetic/Pharmacodynamic (PK/PD) integration suggested that marbofloxacin, a fluoroquinolone already licensed for the treatment of bovine respiratory disease at a daily dosage of 2 mg/kg for 35 days, would be equally clinically effective at 10 mg/kg once (Forcyl (R)), whilst also reducing the risk of resistance. This marbofloxacin dosage regimen was studied using mutant prevention concentration (MPC), PK simulation, PK/PD integration and an in vitro dynamic system. This system simulated the concentrationtime profile of marbofloxacin in bovine plasma established in vivo after a single 10 mg/kg intramuscular dose and killing curves of field isolated Pasteurellaceae strains of high (minimum inhibitory concentration (MIC) MIC =0.03 mu g/mL), average (MIC of 0.120.25 mu g/mL) and low (MIC of 1 mu g/mL) susceptibility to marbofloxacin. The marbofloxacin MPC values were 2- to 4-fold the MIC values for all Mannheimia haemolytica, Pasteurella multocida tested. Marbofloxacin demonstrated a concentration-dependant killing profile with bactericidal activity observed within 1 h for most strains. No resistance development (MIC =4 mu g/mL) was detected in the dynamic tests. Target values for risk of resistance PK/PD surrogates (area under the curve (AUC) AUC24 h/MPC and T>MPC/TMSW ratio) were achieved for all clinically susceptible pathogens. The new proposed dosing regimen was validated in vitro and by PK/PD integration confirming the single-injection short-acting antibiotic concept.