Tibial cortical bone and serum concentrations of clindamycin were compared using two drug delivery methods in dogs. An implantable drug pump, used to continuously infuse clindamycin directly into the cortical bone, was compared with clindamycin administered i.v. Dosage for the direct continuous infusion was 4 mg/kg/day, and 44 mg/kg/day for the i.v. bolus regimen. Serum concentrations of clindamycin were significantly higher during i.v. bolus administration when compared with those achieved during pump infusion (p < 0.05). However, tibial cortical bone concentrations were significantly higher during pump infusion than were those achieved by i.v. bolus. When examining serum and bone clindamycin concentrations over 21 days of direct local infusion, there was no significant difference in concentrations between sampling days within each tissue (p > 0.05). Furthermore, there were significantly greater concentrations of clindamycin in the cortical bone than in the serum at each sampling period (p < 0.05). Results indicate that delivery of clindamycin to canine bone by implantable drug pump achieve significantly higher bone concentrations than i.v. bolus administration of the drug at higher dosages. Direct infusion also can sustain high concentrations in cortical bone without increasing systemic concentrations of clindamycin.
