Novel drying of formulated naproxen sodium using microwave radiation: Characterization and energy comparison

Abstract

The extent of moisture content (MC) present in pharmaceutical formulations has a vital role in controlling the textural properties of the pellet, dispersion of active component and its dissolution kinetics. In particular, hydrophilic drugs such as naproxen sodium (NapS) tend to absorb moisture readily which necessitates the selection of a drying technique to ensure the preservation of drug's textural properties without compromising its pharmaceutical effect and release kinetics. In this paper, a novel drying process for naproxen sodium drug granules has been used successfully by employing microwave radiation technique and compared with other drying techniques. The major objective of the present work is to evaluate the effect of microwave drying technique in the removal of moisture from naproxen sodium and its impact on the textural properties of the final product of tablets powder. The pharmaceutical formulation is synthesized by mixing appropriate amounts of NapS, Poly (vinyl pyrrolidine), and microcrystalline cellulose and moisturized using deionized water to 10, 20 and 30 wt%. Four different drying methods namely vacuum drying (VD), freeze drying (FD), convective drying (CD) and microwave drying (MWD) are used to dry NapS wet granules. The rate of moisture removal and the energy requirement are found to be different for each drying process. The product of drying is also found to have different particle size, morphology, and crystallinity for each process. Among the four techniques, MWD is found to be highly efficient because of its rapid moisture removal which can be ascribed to the interaction of microwave with NapS that has a permanent dipole moment. The results of this work suggest that moisture content of NapS tablets could be reduced rapidly by microwave radiation technique, which has the potential of improving the energy efficiency of the drying process while preserving the textural properties of the drug formulation.