Stereochemical Aspects of the Molecular Pharmaceutics of Ibuprofen

Abstract

Abstract Thermal analysis, thermodynamics of solution and molecular modelling of (+)-ibuprofen and (+)-ibuprofen gave information on how heterochiral or homochiral interactions would affect the processing of ibuprofen. The study confirmed that (±)-ibuprofen exists as a true racemate with a 10% eutectic pure enantiomer composition. Both the racemate and the (+)-isomer crystal unit cells include four molecules and crystallize in the P21/c and P21 space groups, respectively. Thus the intermolecular forces were different in each crystal. As a consequence the (+)-enantiomer lattice was more fragile but only slightly more soluble than the racemate in aqueous media. The solid-state structure contributions to solubility were different for the two crystals (ΔH(+) = 51·1 and ΔH(±) = 32–2 kJ mol−1) but the standard free energies of the solutions were comparable for both compounds.