Original Articles
Sandeep Kumar Vats*, Roop Nara
Abstract
Dissolution enhancement is one of the major focus areas in drug delivery owing to increase in number of new drugs with a limited solubility. Conventional approaches to address this need include selecting suitable polymer(s) followed by optimizing various drug-polymer combinations to arrive at one providing requisite dissolution enhancement. What often lacks in such approaches is (a) evaluation of industrial feasibility to scale-up the developed solid dispersion method and (b) inclusion of solid dispersion into a suitable dosage form for convenient administration to the patient. Regulatory agencies globally are emphasizing on use of quality by design (Qbd) tools in product development. The present work focuses on devising a strategy to optimize a binary solid dispersion formulation with a limited number of statistically designed experiments (DoE) to arrive at a suitable formula and industrially doable process. Polymer screening was undertaken using phase solubility studies with a model drug, Nisoldipine. The screened polymers were evaluated at various drug-polymer ratios and two most industrially feasible methods i.e. Hot-melt extrusion (HME) and solvent evaporation. Dissolution efficiency and T90 were used as parameters for evaluation of dissolution enhancement. Solid dispersion characterization was performed using differential scanning calorimetry (DSC), Fourier transform infra-red spectroscopy (FTIR), dynamic vapor sorption (DVS) and scanning electron microscopy (SEM). Dissolution enhanced formulations were designed using Copovidone. The moisture uptake was reduced in the solid dispersion compared to Copovidone. Hot-melt extrusion was preferred as the method of preparation since it is devoid of solvent usage. The incorporation of solid dispersion at 20% drug load into a tablet resulted in a rapid release tablet dosage form with enhanced dissolution properties.