Polyion complex vesicles containing viscosity enhancer for sustained release of water-soluble low-molecular-weight drugs

Polyion complex vesicles (PICsomes) possess several features that render them as suitable for drug delivery systems. However, retaining water-soluble low-molecular-weight compounds (WLMWCs) remains challenging because of the high permeability of their vesicular membranes. Herein, we propose a new approach for prolonged retention and sustained release of WLMWCs from PICsomes by loading hydroxypropyl methylcellulose to increase the viscosity of the inner aqueous phase. The PICsomes retained 2% to 4% of the WLMWCs, and 100% of the WLMWCs were released within 96 h according to first-order kinetics.