| To prepare the medicinal and cosmetic nonionic surfactant microemulsion with Polyoxyethylene castor oil ether, Cremophor RH-40 and Alkylphenol ethoxylates. The effects of surfactants, cosurfactants and its mixing ratio, oil on microemulsion regions were examined by using the pseudo- ternary phase diagram. The physical stability of the microemulsion was assessed by centrifugation at 4000rpm for 30min, storage at 40±2℃and relative humidity 75±5% for six months, acid, alkali and salt. Drop shape and particle size were investigated by transmission electron microscope. Ocular irritation test was performed in rabbits to evaluate the safety of the microemulsion. The result showed that the formation of microemulsion was dependent on the HLB values of surfactants, the nature of oils and co-surfactants and also the weight ratio of surfactant to co-surfactant. No phase separation was observed in the stability testing. The particle size of the microemulsion was 1~100nm and uniform. The Ocular irritation test showed that the polyoxyethylene castor oil ether and Cremophor RH-40 microemulsions were safe, yet the Alkylphenol ethoxylates microemulsion was not. So, the polyoxyethylene castor oil ether and Cremophor RH-40 microemulsions will be a kind of potent carrier for medicinal and cosmetic drug delivery system.The pseudo- ternary phase diagram was used to select the better nonionic surfactant from Polyoxyethylene castor oil ether and Cremophor RH-40 to prepare arbutin microemulsion with isopropyl myristate. Its average diameter, physical stability and content of arbutin were evaluated by electron microscope, stability tests and UV spectrophotometry respectively. The result showed that the particle size of arbutin microemulsion was 1~100nm and uniform. No phase separation was observed by centrifugation at 4000rpm for 30 minutes and storage at 40±2℃and relative humidity 75±5% for six months. The absorbency and content of arbutin was linearly dependent in 0～80μg/mL, r=0.9993. The average recovery was 99.3%, and the RSD of precision with-day and that between-day were all smaller than three. So, the arbutin emulsion prepared was stable and the means of UV spectrophotometry established was equal to analyse the content of arbutin.The acute toxicity test, skin irritation test and ocular irritation test were performed to evaluate the safty of arbutin microemulsion. The result showed that the acute toxicity LD50 of arbutin microemulsion was 794.05 mg/kg. The score of the skin irritation was smaller than 0.4, which of the ocular irritation was smaller than 3. So, the arbutin microemulsion has law oral toxicity and nonirritating. The arbutin microemulsion was safe.To study the transdermal speed of arbutin microemulsion by pervasion pool, with arbutin aqueous solution and arbutin combination cream as positive controls. The result showed that the average transdermal speed of arbutin aqueous solution, arbutin microemulsion and arbutin combination cream were 60.65±4.99μg﹒cm-2﹒h-1, 376.77±39.88μg﹒cm-2﹒h-1 and 24.7353±4.016841μg﹒cm-2﹒h-1. So, compared to other preparations, arbutin microemulsion has the faster average transdermal speed. It was proper to be used as a transdermal preparation.To investigate the effect of arbutin microemulsion on proliferation, the formation of melanin and the activity of tyrosine enzyme in B-16 cells, with arbutin aqueous solution, arbutin combination cream and vitamin C and vitamin E combination microemulsion as positive controls. The melanin content and activity of tyrosine were determined by oxidation method and the cell proliferation by MTT. The proliferation, the formation of melanin and the activity of tyrosine enzyme all showed inverse proportion with drug concentration in dose-dependent manner. The arbutin microemulsion could effectually inhibit the formation of melanin in low concentration, so it is a new effective whiting agent.Above all, the arbutin microemulsion was stable, safe and effective, according with the standards of a new drug, so it is a proper transdermal preparation as a kind of drug or cosmetic.
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