A comparative study of the rifampicin binding and elution characteristics for collagen- and albumin-sealed vascular grafts.

Abstract

To assess the rifampicin binding and elution characteristics for three protein-sealed vascular grafts. In vitro study. Cardial and Hemashield collagen-sealed and the DeBakey/Vasculour albumin-sealed vascular grafts. The grafts were soaked in a 60,000 mg/l solution of rifampicin at 37 degrees C for 15 min. Bound drug was eluted from the grafts at 37 degrees C and at timed intervals the concentrations of rifampicin remaining in the grafts were determined. Although all three grafts contained high concentrations of rifampicin immediately after soaking these rapidly fell on washing and only a small fraction of the adsorbed rifampicin was tightly bound to the grafts. Rifampicin loading of this tightly bound fraction was similar for the two collagen-sealed grafts (1.7-2.0 mg/kg) but higher for the albumin-sealed graft (16.0 mg/kg). Elution of the tightly bound fraction appeared to follow first-order kinetics with elimination half-lives of 89-141 h. The concentrations of rifampicin remaining in the grafts after eight days were above those needed to inhibit sensitive staphylococci and were 0.7 mg/kg (collagen-sealed grafts) to 3.7 mg/kg (albumin-sealed graft). There is broad equivalence between the rifampicin binding and elution for the two collagen-sealed grafts, but there appears to be slightly higher binding for the albumin-sealed graft.