Disposition kinetics of ciprofloxacin in lactating goats

The pharmacokinetics of ciprofloxacin following intravenous and intramuscular administrations in lactating goats were investigated. Ciprofloxacin was administered as a single dose of 5 mg kg-1 body weight for both routes and was assayed in biological fluids, (serum, milk and urine) to determine its concentrations, kinetic behaviour, and systemic availability. Following a single i.v. injection, the serum concentration-time curve was best described by a two-compartment open model. The elimination half-life (t0.5 beta) was 2.78 +/- 0.08 hours. The extent of serum protein binding of ciprofloxacin in goats was 14.2 +/- 1.4%. Volume of distribution at steady-state was 2.14 +/- 0.07 L/kg. Total body clearance of ciprofloxacin in goats was 14.7 +/- 0.43 ml/min/kg. Following a single intramuscular administration, ciprofloxacin was rapidly absorbed and the mean peak serum concentration (1.92 +/- 0.05 micrograms ml-1) was achieved 1 hour post administration. The systemic availability of ciprofloxacin after intramuscular administration was 95.9 +/- 6.4%. The drug was detected in therapeutic concentrations for 10 hours in serum and milk and for 24 hours in urine. Following intramuscular injection at 5 mg kg-1 body weight for 5 consecutive days, ciprofloxacin showed a cumulative behaviour in serum, milk and urine of goats.