Formulation of Liquid Propofol as a Cocrystalline Solid

This work details a crystal engineering strategy to obtain a novel solid form of the liquid drug molecule propofol using isonicotinamide as a cocrystal former. Knowledge of intermolecular hydrogen bonded supramolecular synthons has been exploited to select a potential cocrystal former based on the likely growth unit formed. The structure of the cocrystal, solved using single-crystal X-ray diffraction, is reported, confirming the molecular packing and key intermolecular interactions adopted in the novel solid form. The potential to enhance a drug’s properties is demonstrated by an increased melting point compared to the native drug form, such that the liquid drug becomes a stable solid at room temperature. Unusually, the propofol/isonicotinamide complex has three structurally similar, temperature-dependent polymorphs, and the crystal structure of each form is reported herein.