Drug eluting sutures: a model for in vivo estimations.

This work is focused on the development of a transient 1-dimension model to describe drug release from a bioresorbable suture thread in a living tissue and the pharmacologic behavior of the active substance being delivered from the device into the tissue. The model is based on fundamental conservation laws, represented by mass balances, being the thread degradation described through population balances and involving detailed hydrolysis kinetics. Monomer, water and drug diffusion are assumed as Fickian, and the increasing of diffusion coefficient is expressed with the "free volume" theory. Drug behavior in tissue is described with a "diffusion and reaction" approach. The model leads to a system of partial differential equations solved by applying the method of lines and then numerically integrated. Simulations allowed to estimate release dynamics and drug behavior in tissue and to obtain spatial and temporal profiles of drug in tissue. Moreover, phase diagrams, which show drug effect in time and space, are here introduced for the first time.