Liposome, gel and lipogelosome formulations containing sodium hyaluronate.

The moisture-imparting effect of sodium hyaluronate (Na-HA) was investigated in liposome, gel and lipogelosome topical formulations. Sixteen liposome formulations were prepared with or without Na-HA (45 kDa) using various ratios of dimyristoylphosphatidylcholine, 1,2-dimyristoyl-sn-glycero-3-phosphatidylglycerol, dipalmitoylphosphatidylcholine and phospholipon 100H. The liposomes were characterized in terms of their structure, composition, zeta potential, Na-HA-entrapment capacity and stability. In particular, scanning electron microscopy, polarized light microscopy, dynamic light scattering and atomic force microscopy were utilized to probe appearance, size and size distribution and lamellarity. The work was then extended to gels using the gelling agents poloxamer (PXM 188 or 407) and Carbopol or Ultrez 21 (U-21), yielding liposome-loaded gel formulations (i.e. lipogelosomes). The in vitro release kinetics of Na-HA from liposomes, lipogelosomes and commercial Na-HA reference formulations were studied via a flow-through cell method. Among the liposomal formulations tested, L6, comprising of Na-HA-loaded phospholipon 100H:stearylamine:cholesterol (7:1:2), displayed optimal traits. The mean particle size, zeta potential and entrapment capacity of L6 were determined as 1900 nm, -20.9 mV and 15.0%. The optimum lipogelosome, LG4, was obtained by incorporating liposome L6 into a U-21 gel at a ratio of 1:1 (w/w). In clinical trials, in-house formulations were applied twice daily to 15 female volunteers. The two-week benefits were assessed against a commercial product; and in all cases, changes of skin humidity, sebum content, pH and wrinkle depth were promising. In particular, the LG4 lipogelosome-based formulation had significantly improved skin hydration and compliance, as evidenced by a moisture content gain of 30.4%.