Hydrophobicity of DS7 and potential competition between dexamethasone and other drugs. (a) Dexamethasone (C atoms shown in yellow) bound to ESA. The color scheme for the protein surface is as follows: gray for the contribution from C atoms, red for that from O atoms and blue for that from N atoms. The link covering the cavity is formed by a salt bridge between Arg208 and Asp323 and is transparent in all panels for clarity. (b) Superposition of the complexes of serum albumin with all of the FDA-approved drugs known to bind to DS7: dexamethasone (yellow; PDB entry 6xk0), ibuprofen (pink; PDB entry 2bxg; Ghuman et al., 2005), diflunisal (gray; PDB entry 2bxe; Ghuman et al., 2005), cetirizine (blue; PDB entry 5dqf; Handing et al., 2016), testosterone (green; PDB entry 6mdq; Czub et al., 2019), halothane (gold; PDB entry 1e7b; Bhattacharya et al., 2000), naproxen (pale green; PDB entry 4zbr; Sekula & Bujacz, 2016), 6-MNA (cyan; PDB entry 6u5a; Czub et al., 2020), diclofenac (violet; PDB entry 6hn1; J. A. Talaj, A. Bujacz & G. Bujacz, unpublished work) and etodolac (orange; PDB entry 5v0v; Czub et al., 2020). (c) Superposition of the ESA–dexamethasone (yellow; PDB entry 6xk0) and ESA–testosterone (green; PDB entry 6mdq; Czub et al., 2019) structures. Dexamethasone and testosterone largely overlap at DS7. Both steroids are shown in stick representation with O atoms in red; dexamethasone is shown with C atoms in yellow and the F atom in cyan, while testosterone is shown with C atoms in green.