Molecular docking, molecular dynamics simulation, preparation, and characterization of naltrexone-phospholipid complex: A novel cargo with improved loading into multivesicular liposomes

Abstract

Naltrexone hydrochloride (NTX), a water-soluble opioid receptor antagonist, is prescribed widely for opioid and alcohol dependence and pain reduction. However, the significant limitations of NTX are low lipophilicity and extensive first-pass metabolism. This study aimed to design and prepare a novel phospholipid complex of NTX and load it into multivesicular liposomes (MVLs). In silico studies, including molecular docking and molecular dynamics (MD) simulation, were performed to determine the interactions between NTX and phospholipid and evaluate their best molar ratio to prepare the complex, respectively. The NTX phospholipid complex was prepared by solvent evaporation technique and characterized by PXRD, SEM, FTIR, 1HNMR, solubility study, and n-octanol/water partition coefficient analyses. NTX-SPC complex-loaded MVLs (NTX-SPC-MVLs) were prepared by the double-emulsion method and characterized by encapsulation efficiency (EE)%, size, PXRD, FTIR, SEM, and release pattern. MD simulation reported the 1:1.5 M ratio of NTX to phospholipid as the best molar ratio. Complexation led to reduced water solubility and enhanced n-octanol/water partition coefficient. Loading of NTX-SPC complex into MVLs enhanced EE and extended the release duration in comparison to NTX MVLs. Thus, the NTX-SPC complex may be an appropriate system to enhance the physicochemical features of NTX and improve the EE in vesicular drug delivery systems like MVLs.

Keywords

• Naltrexone HCl
• Phospholipid complex
• Multivesicular liposomes
• Molecular docking
• Molecular dynamics simulation