Drug release from glutaraldehyde-treated fibrin gels

Glutaraldehyde treatment of dexamethasone-containing cylindrical fibrin gels (obtained by the thrombin-induced polymerization of fibrinogen in the presence of the drug) causes cross-linking of the gels and modification of the pore structure. The effect on the release of dexamethasone was assessed by measuring the diffusion coefficient of the drug across treated and untreated gels; diffusion across the treated gels was significantly decreased as compared with untreated gels, but was little affected by the concentration of glutaraldehyde used in the treatment. In biodegradable tests, the treated gels (all concentrations of glutaraldehyde) were resistant to digestion even in the presence of plasmin, but untreated gels were digested, and the digestion rate was accelerated by plasmin. The volume of the gels was progressively reduced as the concentration of glutaraldehyde was increased or the amount of fibrinogen was decreased, but the extent of the reduction did not correlate with the changes in the diffusion coefficient.