Release Kinetics of Tobramycin Sulfate from Polymethylmethacrylate Implants

Abstract

The effects of various formulation factors on the in vitro release characteristics of spherical polymethylmethacrylate implants were studied. Physical and mathematical models were proposed to describe observed in vitro release profiles. The in vitro release data could be described by a biexponential equation of the type: fraction of tobramycin remaining in the implant at time t = Ae^−αt + Be^−βt, where α and β represent the rate constants for the initial rapid and subsequent slow phases of release. The influence of drug loading, volume of dissolution medium, implant size, type of commercial cement and the incorporation of water soluble additives on the release profiles as well as the α and β rate constants is described