Stabilizers used in nano-crystal based drug delivery systems

Abstract

Nanocrystals have emerged as a viable tool to increase oral bioavailability of poorly water soluble oral solid dosage drugs. They also enable parenteral administration of these drugs as nanosuspensions. The high free surface energy, due to the large surface area to volume ratio of nanocrystals, makes them prone to aggregation, that can result in physical instability and loss of the previously increased solubility/dissolution. Stabilizers are incorporated into nanocrystalline formulations to prevent aggregation. These include excipients such as polymers and surfactants. They achieve stabilization though electrostatic repulsion and/or steric hindrance. This article focuses on aggregation in nanocrystal based formulations, stabilizers for the inhibition of aggregation, classification of stabilizers, properties of stabilizers and the mechanisms involved in stabilization. A review of stabilizers, drugs that have been stabilized, formulation types and methods for generating nanocrystals will be presented. Current challenges and future trends in the field of stabilizers will also be reviewed.