Pharmacokinetics of Metronidazole Administered as a Single Oral Bolus to Red Rat Snakes, Elaphe guttata

ABSTRACT The pharmacokinetics of metronidazole was evaluated in 16 red rat snakes, Elaphe guttata, after a single oral dose of 50 mg/kg (n=8) or 150 mg/kg (n=8). Blood samples were collected at predetermined intervals over a 48 hr period. Plasma concentrations of metronidazole were measured using high performance liquid chromatography (HPLC). Metronidazole dosed at 50 mg/kg was eliminated with a half-life of 11.1 hr. The apparent volume of distribution (steady state) was 0.053 L/kg, the apparent oral clearance was 3.04 ml/hr, and the mean residence time was 18.5 hr. The plasma concentration of metronidazole exceeded the recommended minimum inhibitory concentration (MIC) in both treatment groups at all time points for at least 48 hr. Based on this study it can be concluded that oral administration of 50 mg/kg of metronidazole to red rat snakes every 48 hr would maintain more than adequate plasma concentrations against susceptible anaerobic bacteria and protozoa.