Nanosuspensions – A versatile drug delivery platform
Formulation of poorly soluble drugs is a challenging problem and nanosuspensions, nanosized drug dispersions, can be considered as a solution. Nanocrystals of pure drugs can be formulated as an aqueous nanosuspension in the presence or in the absence of stabilizers, as surfactants or polymers. This nanotechnological approach is suitable for molecules which are poorly soluble in aqueous and organic solutions. Nanosuspensions can be administered by oral, parenteral, ophthalmic, pulmonary and topical routes. The preparation methods are classified in two categories: “top down”, such as milling techniques and high pressure homogenization, and “bottom up”, such as precipitation methods, emulsion as template and supercritical fluid. Nanosuspension technology represents an interesting strategy for the efficient delivery of drugs.
Pharmaceutical companies estimate that about the 40% of new developed compounds shows limited solubility and dissolution rate with a low bioavailability after oral administration (1). Poorly water-soluble drugs generally are a great challenge in drug formulation. Many technological strategies consisting of the addition of cosolvents, surfactants and cyclodextrins have been proposed and used in order to improve drug solubility. Smart formulation approaches, emerging from nanotechnology, such as liposomes, nanoparticles based on lipidic or polymer components, emulsions and nanosuspensions of drug nanocrystals, are also applicable. All these methods aimed at ensuring that drugs are not only pharmacologically active, but also have good solubility to guarantee fast dissolution at the site of administration. Among these techniques, nanosuspensions not only can solve the problem of solubility and bioavailability, but also can alter the pharmacokinetic profile of the drug, which may improve safety and efficacy. This review concerns a general nanosuspension overview, focusing the attention on their main properties and on the most used methods of prep ...