[The bioequivalence of two injectable solutions of spiramycin in young cattle]. / Etude de la bioéquivalence de deux solutions injectables de spiramycine chez le jeune bovin.

A bioequivalence study was performed in 12 young cattle in order to compare 2 injectable solutions of spiramycin containing 60 M IU/100 ml (Suanovil 20) and 100 M IU/100 ml, respectively. In a cross-over design, a single dose of 100,000 IU/kg bw was administered intramuscularly, allowing 8 d between the 2 administrations. For each formulation, the following parameters were determined: maximum serum concentration (Cmax) and time to reach peak concentration (Tmax), mean residence time (MRT), area under the time-concentration curve (AUC), half-life (t1/2 beta). Statistical analysis of t1/2 beta, Tmax (Wilcoxon's test) and Cmax, MRT, AUC (ANOVA), indicated no significant differnces between the two formulations (P greater than 0.05). Westlake's confidence intervals calculated for a 95% probability were 23.1% for Cmax, 11.1% for MRT and 13.2% for AUC, respectively, which confirmed the bioequivalence of the 2 formulations. It must be noted that an experimental design using 12 animals is generally insufficient to demonstrate bioequivalence, according to the recommended statistical criteria.

[Doxycycline: pharmacokinetics and suggested dosage in dogs and cats]. / Doxycycline: farmacokinetiek en doseringsvoorstellen bij hond en kat.

Data on the pharmacokinetics of doxycycline in dogs and cats are reported. Doxycycline was given orally in the form of palatable tablets of Ronaxan. Tablets of 100 mg of doxycycline (as hyclate) were used in dogs, whereas cats were given tablets of 20 mg. The doses administered were 10 mg/kg in both species. The pharmacokinetics of doxycycline in dogs and cats were compared with those obtained in man (at a dosage of 3 mg/kg/day). It is concluded that a dosage of 10 mg/kg/day of doxycycline is required to obtain effective plasma concentrations in dogs and cats for 24 hours, when this dose is administered once daily.