ABSTRACT
OBJECTIVE: To prepare naproxen microemulsion-gel with high drug content and adhesiveness, and investigate its in vitro transdermal delivery ability. METHODS: The ranges of microemulsion with the mixture of Tween 80 and Tween 20 as surfactant, carbitol as cosurfactant, peponida as oil, were defined through construction of the pseudo-ternary phase diagrams. Drug-loaded microemulsions were prepared by phase transfer temperature method. Naproxen microemulsion-gel was prepared by directly adding carbomer 980 into its microemulsion. The diffusion studies of all formulations were performed using a drug diffusion apparatus. The mean droplet sizes of naproxen microemulsion were measured via dynamic light scattering(DLS) on a Zetasizer, their microstructures were observed by transmission electron microscope(TEM). RESULTS: Microemulsion range was largest when the mass ratio of Tween 80 and Tween 20 was 3:1, surfactant and cosurfactant was 2:1. While the microemulsion composed of 5% peponida, 35% emulsifier and 60% water, drug loaded in microemulsion can attain 4%, which was accorded with the characterization of microemulsion. Adding 2.5% carbomer 980 into optimization microemulsion, even and transparence microemulsion-gel was obtained, which has the combination of o/w microstructure of microemulsion and the three-dimensional gel network of hydrogel. The viscosity of microemulsion-gel was increased from 104.5 mPa · s to 18.9 Pa · s, the steady-state permeation rates through excised cavia skin increased from(531.912±1.3) to(640.327±0.7) μg · cm-2 · h-1. CONCLUSION Naproxen microemulsion-gels prepared by selected carbitol as cosurfactant can obtain high drug content and percutaneous absorbtion, exhibit favourable adhesiveness, which may be a promising new dosage form for transdermal delivery of naproxen.