The theory of a time-dependent effect of
amoxycillin was examined in a model of porcine Actinobacillus pleuropneumoniae (Ap)-
infection using clinically relevant dosage regimens. Twenty hours after
infection of fourteen pigs, when clinical signs of
pneumonia were present, one group of pigs received a single dose of
amoxycillin (20 mg/kg, i.m.), whereas another group received four doses of 5 mg/kg injected at 8-h intervals. A similar AUC of the plasma
amoxycillin concentration versus time curve was obtained in the two groups, whereas the maximum concentration was threefold higher using the single high dose. Plasma
amoxycillin was above the MIC for twice as long using the fractionated dosage scheme. The condition of the animals was evaluated by clinical and haematological observations combined with quantification of biochemical
infection markers:
C-reactive protein,
zinc and
ascorbic acid. Within 48 h of treatment, the pigs in both treatment groups recovered clinically. No significant differences in the time-course of clinical observations or plasma concentrations of the
biomarkers of
infection were observed between the two treatments. In conclusion, the efficacy of these two dosage regimens of
amoxycillin was not significantly different in treatment of acute Ap-
infection in pigs.