A Review on Co-crystals of Herbal Bioactives for Solubility Enhancement: Preparation Methods and Characterization Techniques

Co-crystallization is a promising approach for improving physical and pharmacological properties of API, viz., solubility, dissolution rate, stability, hygroscopicity, tablet ability, mechanical properties, bioavailability, and therapeutic efficacy. Different methods for the preparation of pharmaceutical co-crystals have been discussed. Instrumental and physicochemical characterization methods have also been included. Herbal bioactives are potential candidates for co-crystallization to improve solubility, mask taste, and improve bioavailability. Literature on the development of co-crystals of herbal bioactives like curcumin, quercetin, berberine, resveratrol, naringenin, and miscellaneous herbal compounds has been reported systematically in the present review. In conclusion, co-crystallization of herbal bioactives is a promising method for enhancing their physical properties. However, toxicological, stability, regulatory, and scaleup issues must be adequately addressed before commercial viability can be expected.