Polycaprolactone-Coated Alginate/b-Tricalcium Phosphate Beads to Locally Deliver Vancomycin: A Pilot Study

Abstract

Orthopedic device-related infections (ODRI) are difficult to control and the management of ODRI most frequently includes surgery and long-term antimicrobial therapy. Local application of vancomycin through a biodegradable carrier like alginate would provide a valuable tool, although it is hard to control the drug-release for a prolonged period of time due to its permeability. Coating with hydrophobic polymer such as polycaprolactone (PCL) may sustain the vancomycin release. We fabricated four types of vancomycin containing alginate/b-TCP beads (uncoated, coated with 1.25 w/v%, 2.5 w/v%, and 5.0 w/v% PCL). Scanning electron microscope (SEM) revealed that b-TCP particles were uniformly distributed on the surface of the uncoated beads and the most homogenous coating layer was observed using 2.5 w/v% PCL. Vancomycin release and its bioactivity were measured at the designated time points (1, 4, 12, 24 hours, then every day until disintegration). Burst release occured on the first hour, day 1, 2 and 6 respectively. The beads without coating dissolved at day 3, and those with different coatings dissolved at day 5, 6, and 9. The minimum concentration of the vancomycin in the elution was approximately 5 mg/L, higher than the vancomycin’s minimum inhibitory concentrations (MICs) for Methicillin-resistant Staphylococcus aureus (MRSA). PCL-coated alginate/b-TCP beads loaded with vancomycin may provide a potential local drug delivery device for the adjuvant antimicrobial therapy of the ODRI.