Ibuprofen (an anti-inflammatory drug) has been loaded onto two different surfactant-templated silicas (SBA-15 and MCM-48). To evaluate the effect of the drug-solvent combination on the loading capacity of the silica, we have performed ibuprofen adsorption experiments using 10 different solvents; we have interpreted our experimental results assuming a chemical equilibrium between the ibuprofen adsorbed on the silica and that remaining in solution. To estimate the equilibrium constant for different solvents, we have calculated the free energy in solution for the ibuprofen molecule using the polarizable continuum model (PCM) to take the solvent into account. The results have been analyzed statistically to eliminate the effects of the dispersion of experimental data; results reveal a statistically significant (95-99%) linear relationship between the ibuprofen loading capacity and its free energy in solution calculated with the PCM solvation model. In addition, useful relationships between loading capacity and dielectric constant and molecular size of the solvents are established.