Single-dose pharmacokinetics of cefazolin in bovine synovial fluid after intravenous regional injection.

The pharmacokinetic properties of cefazolin in the synovial fluid of the tibiotarsal joint were determined in 10 healthy mature cattle after intravenous regional injections of 250 mg cefazolin. A pneumatic tourniquet was positioned proximal to the tibiotarsal joint and the intravenous injection was performed distal to the tourniquet. Synovial fluid concentrations of cefazolin increased in the first 30 min and fluctuated between 54.7 +/- 11.0 micrograms/ml (mean +/- SEM) and 73.2 +/- 13.2 micrograms/ml in the following 90 min while the tourniquet remained inflated. After tourniquet removal, synovial fluid concentration-time curves followed first-order one-compartment model decay in most of the animals with an elimination half-life of 0.82 h (harmonic mean). Therapeutic concentrations of cefazolin in the synovial fluid of normal joints were reached and this injection technique could be used as an alternative to systemic administration of antibiotics to provide adequate concentrations in a localized area.