Dissolution Rate Enhancement of Nimesulide Using Electro-spinning and Cogrinding Techniques: A Comparative Study

Nimesulide is a selective Cyclooxygenase - 2 enzyme inhibitor useful in inflammatory conditions. It belongs to class 2 of Biopharmaceutical classification system (BCS), which has very low water solubility leading to low oral bioavailability. The objective of present study was to enhance the solubility and dissolution rate of poorly soluble model drug, nimesulide. For the same purpose, two approaches were used. First approach includes Electrospinning technique, and the second approach is co-grinding technique. In Electrospinning technique, the solution containing drug and polymer (PVP K-90) dissolved in an organic solvent was taken and made in to nanofibers of different drug- polymer ratios (1:1, 1:2, 1:3, 1:4, 1:5) using electro-spinning apparatus. In the co-grinding technique, mixtures with different ratios (1:1, 1:3, 1:5, 1:7, 1:9) of drug and carrier were prepared employing potato starch, lactose, microcrystalline cellulose, sodium starch glycolate and treated agar as carriers. Of the two approaches, nanofibers provided a better solubility enhancement when compared to co-grinding mixtures and pure drug. The optimized formulation (nanofibers) was characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Differential scanning calorimetry (DSC) and the in-vitro dissolution rate studies. The optimized nimesulide nanofiber formulation displayed nearly 50- fold faster dissolution compared to the pure drug and the optimized co-ground mixture. It has also shown two to three- fold greater anti-inflammatory activity in Wistar albino rats as compared to pure drug. Hence, nanofibers produced by electrospinning technique provided a scope for enhancing the solubility and dissolution rate by encapsulating poorly water soluble drugs within the polymeric matrix leading to potential bioavailability enhancement through the oral or topical routes.