Serum pharmacokinetics of clindamycin hydrochloride in normal dogs when administered at two dosage regimens

The aim of this cross-over study was to compare clindamycin pharmacokinetics in the serum of clinically normal dogs when administered orally at two dosage regimens (5.5 mg/kg, twice daily, and 11 mg/kg, once daily), separated by a 1 week wash-out period. Serum samples were obtained from six clinically normal laboratory beagles before, 3, 6, 9 and 12 h after the first and fifth dose of clindamycin at 5.5 mg/kg, twice daily, and before, 3, 6, 9, 12, 18 and 24 h after the first and third dose at 11 mg/kg, once daily. Serum clindamycin concentrations were determined by reverse-phase liquid chromatography coupled with mass spectrometry. Results were analysed using Student's paired t-test, at a 5% level of significance. Values of pharmacokinetic parameters that differed significantly between the two dosage regimens included the following: maximal concentration and area under the concentration-time curve were higher at 11 mg/kg, once daily, than at 5.5 mg/kg, twice daily; and, more importantly, the ratio of AUC(0-24) to the minimal inhibitory concentration (MIC) value of 0.5 μg/mL for a 24 h period (AUC(0-24)/MIC) was higher when clindamycin was administered at 11 than at 5.5 mg/kg, at least during the first day of drug administration. Therefore, a better pharmacokinetic profile may be expected when clindamycin is administered at 11 mg/kg, once daily, for the treatment of canine pyoderma caused by Staphylococcus pseudintermedius.