State of the Art of Pharmaceutical Solid Forms from Crystal Property Issues to Nanocrystals Formulation.

The solid form screening of active principal ingredients is a challenge for the pharmaceutical drug development since more than 80% of the marketed drugs are formulated in the solid form. A broad and comprehensive study of the various solid forms of the matter is needed to enhance its translation to clinic. Therefore, the most suitable solid form has to be taken into consideration regarding ex- and in-vivo stability, targeting, solubility, dissolution rate, and bioavailability. In this review, techniques of solid form screening are reported, including differences in the solid forms such as polymorphs, solvates, salts, co-crystals and amorphous particles. Moreover, solid drug size reduction is also discussed, with an insight into the emergence of drug nanocrystals formulation. An overview of the smallest nanocrystals in the literature and in the market, is reported. Their application and administration routes are also addressed.