The crystal structure of loteprednol etabonate Form II has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Loteprednol etabonate Form II crystallizes in the space group P21 (#4) with a = 11.96312(6), b = 14.91862(5), c = 6.75715(3) Å, β = 94.1584(3)°, V = 1202.796(6) Å3, and Z = 2. The crystal structure is characterized by herringbone layers in the ab-plane. The anisotropic displacement ellipsoid of the Cl atom is not oriented in a way which corresponds to a chemically sensible motion of this atom. The sample suffered damage in the X-ray beam, probably involving photolysis of the C–Cl bond. The most prominent hydrogen bond is the O–H⋯O hydrogen bond between the hydroxyl group and the carbonyl group of the steroid A ring. This hydrogen bond links the molecules into C1,1(9) chains along the b-axis. The powder pattern is included in the Powder Diffraction File™ (PDF®) as entry 00-066-1602; this study will allow inclusion of the atomic coordinates to the PDF entry.
