Impact of spray drying over conventional surface adsorption technique for improvement in micromeritic and biopharmaceutical characteristics of self-nanoemulsifying powder loaded with two lipophilic as well as gastrointestinal labile drugs

Abstract Advantage of spray drying technique over the conventional surface adsorption technique for co-formulation of solid SNEDDS (S-SNEDDS) of curcumin (CRM) and duloxetine (DXH) is discussed. Liquid SNEDDS were prepared using castor oil (20% w/w), Tween-80 (40% w/w) and Transcutol® P (40% w/w) as oil, surfactant and co-surfactants containing both CRM and DXH. S-SNEDDS were formulated by adsorption of liquid SNEDDS onto porous hydrophilic and hydrophobic carriers through spray drying and surface adsorption techniques. The percentage drug loading for CRM and DXH in optimized L-SNEDDS was 87.22 ± 1.87 and 92.32 ± 0.19%, mean droplet size, 113.14 ± 1.14 nm; polydispersity index, 0.20 ± 0.026, and zeta potential − 13.2 mV, respectively. Prepared formulation was evaluated for parameters such as, oil adsorption tendency, micromeritic characteristics, disintegration and dissolution behaviour to identify suitable carrier for conversion of L-SNEDDS into S-SNEDDS. Among the carriers used, Syloid® 244FP revealed highest oil adsorption capacity. Spray drying of L-SNEDDS using Syloid® 244FP as carrier further improved micromeritic properties with lower angle of repose (22.18 ± 0.22°), higher flow rate (4.33 ± 0.26 g/s), lower true (1.23 ± 0.22 g/cm3), bulk (0.202 ± 0.05 g/cm3) and tapped density (0.216 ± 0.07 g/cm3). In vitro dissolution and ex-vivo permeation studies revealed non-significant (P > 0.05) drugs' release from S-SNEDDS powders/tablets viz-a-viz their L-SNEDDS formulation. SNEDDS were found to be remarkably superior over the unprocessed drugs in their dissolution and permeation studies. They were found to be stable in terms of droplet size, dissolution pattern, tablet hardness and assay when subjected to stability testing. Scanning Electron Microscopy, Differential Scanning Calorimetry and powder X-ray diffraction studies revealed that crystalline drugs were converted to their amorphous state in the SNEDDS formulations. Spray drying technique has, therefore proved to distinctly improve the micromeritics and biopharmaceutical attributes in the co-formulation of curcumin and duloxetine S-SNEDDS.