Although that previous computational study investigated the same zeolite framework and similar Si/Al ratios as the earlier experimental study by Datt et al., some important disagreements were noted: First, the DFT-calculated IR spectra of 5-FU-loaded FAU showed poor agreement with experimental results. Second, all three samples studied experimentally showed only partial 5-FU release (and, in the case of the most Al-rich sample, almost no release at all), while the computations indicated a fast, complete release of the drug from the zeolite host. This discrepancy was explained with the dominant adsorption of 5-FU at Lewis acidic Aloct sites in the experimental samples, whereas the DFT calculations considered only Brønsted acidic framework protons. The present work addresses this issue by explicitly considering the interaction of 5-FU with octahedral Al sites in FAU-type zeolites.