Fibrin based drug delivery systems

Fibrinogen is the natural substrate for thrombin, the final proteolytic enzyme of the blood coagulation cascade. Following reaction with thrombin, fibrinogen is converted into fibrin monomers which then spontaneously polymerize into fibrin threads forming the fibrin matrix. This biochemical reaction between fibrinogen and thrombin has been used to produce natural, biodegradable, biocompatible systems for sustained drug delivery. Three potential delivery systems have been explored: 1) fibrin microparticles with drug entrapped are produced by an emulsion process, 2) reaction between fibrinogen adsorbed on suspended drug and thrombin in solution results in the formation of fibrin-coated drug particulates, and 3) fibrin sheets suitable as implants have been cast with drug entrapped. The drug release behavior of both small and large molecular weight substances from these systems was evaluated.