Preparation and evaluation of nanosuspensions for enhancing the dissolution of poorly soluble drugs

Poorly water-soluble compounds are difficult to develop as drug products using conventional formulation techniques and are frequently abandoned early in discovery. In the present study, the melt emulsification method traditionally used to prepare solid lipid nanoparticles was adapted to produce drug nanosuspensions. The method was evaluated in comparison with the well known solvent diffusion process for ibuprofen as a model drug. Control of the preparation variables (stabilizers, drug content, homogenization procedure and cooling conditions) allowed formation of nanosuspensions with diameters less than 100 nm. The major advantage of the melt emulsification method over the solvent diffusion method is the avoidance of organic solvents during production, although the mean particle size is slightly greater. The combination of Tween 80 and PVP K25 as stabilizers yields nanosuspensions with the smallest average particle size. The formulation of ibuprofen as a nanosuspension, either in the form of lyophilized powder or granules, was very successful in enhancing dissolution rate, more than 65% of the drug being dissolved in the first 10 min compared to less than 15% of the micronized drug. The increase in in vitro dissolution rate may favourably affect bioavailability and improve safety for the patient by decreasing gastric irritancy.