Nanocrystals as a master key to deliver hydrophobic drugs via multiple administration routes

The poor aqueous solubility of many approved drugs and most new chemical entities poses a challenge to drug delivery scientists working in academic and industrial labs. Despite the high pharmacological activity these drugs may have, their limited water solubility leads to poor absorption and consequently to sub-therapeutic drug concentrations in target tissues. The formulation of drug nanocrystals (NCs) has emerged as one the most promising approaches for increasing the biopharmaceutical performance of hydrophobic drugs. Initially aimed at increasing the absorption of drugs administered orally, NCs have been increasingly utilised to allow drug delivery via multiple routes, namely, parenteral injections, transdermal, ocular, intranasal, and pulmonary. This review aims to describe the recent progress in the field and demonstrate how the NCs technology enabled the delivery of hydrophobic drugs through multiple administration routes.