Medullary Plasma Pharmacokinetics of Vancomycin After Intravenous and Intraosseous Perfusion of the Proximal Phalanx in Horses

Abstract

To study the pharmacokinetics of vancomycin in plasma obtained from the medullary sinusoids of the proximal phalanx (P1) after intravenous (IV) and intraosseous (IO) regional limb perfusion (RLP). Experimental study. Twelve horses. IV and IO RLP were performed in 2 groups (n = 6) of horses. Vancomycin hydrochloride (300 mg in 60 mL 0.9% NaCl) was randomly infused in 1 front limb, with the contralateral limb as control (60 mL 0.9% NaCl). A hole was drilled in the lateral cortex of P1, and blood samples from the medullary sinusoids of P1 were collected before infusion, and 15, 30, 45, 65, and 90 minutes after beginning infusion. Samples were centrifuged and plasma vancomycin concentrations determined. Vancomycin concentrations were compared over time and between routes using a 2-way repeated measures ANOVA. Pharmacokinetic variables were compared with a Kolmogorov-Smirnov test. Significance was set at P<.05. No vancomycin-induced clinical side effects such as lameness or swelling were observed. Both techniques, IV and IO, produced high vancomycin concentrations in the sinusoidal plasma of the P1, which remained above the minimum inhibitory concentration value for methicillin-resistant Staphylococcus aureus (MRSA) during the 90 minutes study. Concentrations and pharmacokinetic variables were not significantly different comparing both routes. IV and IO routes produced similar antimicrobial perfusion of the medullary cavity of P1. Either IV or IO routes for perfusion are likely to be equally selected when planning RLP with vancomycin.