Wet Granulation as a Solidification Strategy for Converting Aqueous Nanosuspensions into Solid Dosage Forms

Background: The well-established biopharmaceutical advantages provided by nanosuspensions (NSs) make their conversion into solid oral dosage forms particularly appealing for improving both patients' compliance and product stability. However, such a transformation continues to represent a significant challenge. Aim: This study explored manual wet granulation (WG) as a laboratory-scale strategy to transform an NS containing cinnarizine (CN) into granules, which were intended for direct administration or to be further processed. Methods: A range of polymers, characterized by different interaction mechanisms with aqueous fluids, were employed as carriers to incorporate the CN-containing NS during manual WG. The resulting granules were thoroughly characterized before tableting. Results: The NS-loaded products exhibited satisfactory physio-technological properties, effective nanocrystal redispersibility, high drug load efficiency, and expected in vitro performance. Moreover, they turned out to be suitable intermediates for mini-tablet production. Conclusions: Based on the data collected, WG turned out to be an effective lab-scale method for transforming an aqueous CN-containing NS into solid products (i.e., granules and mini-tablets), while preserving the starting properties of the drug nanocrystals. By adjusting formulation and process parameters, a variety of release kinetics were achieved, highlighting the value of the pursued approach, especially for early-stage screening of new drug candidates belonging to class II of the biopharmaceutical classification system.