Ketoconazole - p-aminobenzoic acid cocrystal: revival of an old drug by crystal engineering.

The 1:1 cocrystal of the antifungal agent Ketoconazole with p-aminobenzoic acid was successfully crystallized and systematically characterized from a physical and pharmacological point of view. Crystal structure determination confirmed the cocrystal identity, giving full insight in its crystal packing and degree of disorder. Powder dissolution measurement revealed a 10 fold aqueous solubility increase that induce a 6.7 fold oral bioavailability improvement compared to Ketoconazole. In vitro cell assays showed good toxicity profile of the cocrystal with lower oxidative stress and inflammation, and enhanced antifungal activity against several Candida species. The in vivo study of the cocrystal indicated similar pharmacokinetic profile and liver toxicity with increased transaminases, as reported for Ketoconazole. Notably, besides minor signs of inflammation, no morphological changes in liver parenchyma or signs of fibrosis and necrosis were detected. The enhanced solubility and oral bioavailability of the cocrystal over Ketoconazole, together with the improved antifungal activity and good in vitro/in vivo toxicity indicate its potential use as an alternative antifungal agent to the parent drug. Our results bring evidence of cocrystallization as a succesful approach for bioavailability improvement of poorly soluble drugs.