Rifampicin loading of vascular grafts

Antibiotic-bound arterial prostheses may contribute to the management of prosthetic infections. The in-vitro absorption and release of rifampicin was measured in four different polyester arterial prostheses, including unsealed VP 1200, gelatin-sealed Gelsoft, collagen-impregnated Hemashield and gelatin-sealed Unigraft. Gelsoft grafts bound more rifampicin than unsealed VP 1200. Rifampicin concentrations with the gelatin sealed to Gelsoft grafts reached a threshold when the rifampicin concentrations of the soaking solution were 10 mg/mL or more. Rifampicin adsorption plateaued after 15 min of soaking VP 1200, and peaked after 25 min of soaking Gelsoft. pH variations did not significantly influence antibiotic binding. Prosthesis-bound rifampicin concentrations decreased rapidly after soaking, but a significant portion of the antibiotic remained associated with the material after 7 days. Release was slower with Gelsoft than with VP 1200 during the first 3 h, but after 24 h, the amounts of rifampicin released were similar in the two materials. Other experiments were performed in dogs receiving sealed grafts as infrarenal aortic bypass after soaking the material in a 1 mg/mL solution of rifampicin in normal saline. After 3 days of implantation, the amount of rifampicin in explanted grafts was higher in Gelsoft and Hemashield than in Unigraft. This study confirms that rifampicin bonding to prosthetic material occurs and is enhanced by sealed collagen or gelatin.