A Study Of Compound Methy Salicylate Submicroemulsion-based Gel

Recently, much attention has been focused on increasing permeation rate of lipophilic drug for enhancing therapeutic effect. In order to obtain a high drug-loading, powerful penetration capacity, good stable submicroemulsion system, camphor, menthol and methy salicylate as drug models were loaded into the submicroemulsion system, followed by incorporating into gel. The main results are as follows:1. The suitable types and amounts of surfactants, cosurfactants and oils were optimized according to droplet size and stability of the submicroemulsions. The system consisting of poloxamer 407, soybean lecithin, Tween 80 and 1, 2-propanediol had good stability and its average diameter was 59.6 nm. The amount and the order of the addition of carbomer 940 into submicroemulsion were investigated according to droplet size, viscosity and appearance. The accumulative amount of camphor, menthol, methy salicylate from the optimum submicroemulsion containing 1% poloxamer 407, 1% soybean lecithin, 4% Tween 80 was 1078±37μg·cm-2,343.68±23.2μg·cm-2,430.4±25.6μg·cm-2, respectively.2. The high-pressure homogenization and ultrasonic technology were used to prepare submicroemulsions.The average diameter of submicroemulsion obtained at the pressure of 800 bar with 8 circles was 50.2 nm and that prepared by ultrasonic technology with 90 cycles was 124.1 nm. The high-pressure homogenization is much better than altrasonic technology for industrial production.3. A gas chromatography method for determining the content of camphor, menthol and methy salicylate in submicroemulsion-based gel was established. A SE-54 column(30 m×0.32 mm, 0.2μm)was used and cyclohexanone acted as inter standard. FID was used and the detector temperature was 250℃. The injector temperature was set at 230℃. Column temperature raised by programming. The linear scope of camphor, menthol, methy salicylate was 0.178~1.602 mg·mL-1(r = 0.9999), 0.172~1.548 mg·mL-1(r = 0.9998), 0.399~3.591 mg·mL-1(r = 0.9999). The average recovery is 100.13%, 99.73%, 99.80%, and all RSD less than 2%(n = 9).The method is simple, accurate and reproducible. It can be reliable for the quality control of submicroemulsion-based gel.4. The stability of submicroemulsion-based gel was evaluated. The average diameter of this system changed from 63.5 nm to 89.1 nm at 40℃during a period of 10 days. However, no significant change of average diameter of submicroemulsion was observed at -15℃. The results indicated that this system should be stored at a relatively low temperature.