Method for predicting sorption of small drug molecules onto polylactide

A method has been developed to predict the percent sorption of small drug molecules onto polylactide (PLA). In this method, molecular modeling is first used to calculate the interaction energy between the adsorbate and PLA. Alternatively, the adsorbate-PLA interaction energy can be calculated by summing the adsorbate functional group contributions to the interaction energy. These functional group contributions have been found in this study. The adsorbate-PLA interaction energy is then substituted into a linear equation to predict the natural log of the sorption equilibrium constant, and the percent sorption is obtained from this value. This linear equation has been developed based on experimental sorption data for dyes on PLA. The predicted percent sorption of two small drugs on PLA has been verified with experimental data. Our method possibly could be used to select appropriate drugs for use in controlled release studies involving PLA. This method also could be used to calculate the functional group contributions to the interaction energies between other drugs and polymers and to predict their percent sorption onto those polymers, which could be used to select drugs suitable for controlled release studies involving those polymers.