RESUMO
Vetiveria zizanioides (vetiver) contains viscous volatile oil, which has the ability to repel mosquitoes similar to citronella oil, a well-known mosquito repellent in tropical countries, like Thailand. The objectives of the current study were to formulate the stable oil-in-water vetiver oil lotions using Simulgel FL as a liquid emulsifier, to investigate the physicochemical properties of the prepared lotions and to evaluate the in vitro release characteristics of the stable vetiver oil lotions. In this work, the concentrations of Simulgel FL ranged from 1% to 3% weight in weight, whereas the concentrations of vetiver oil were varied: 2.5%, 5%, and 10% weight in weight. The suitable concentration of Simulgel FL was found to be 3% weight in weight. For comparison purposes, oil-in-water citronella oil lotions (10% weightin- weight citronella oil) were also prepared with similar ingredients. A mixture of vetiver oil and citronella oil (1:1 by weight) was also used as an active ingredient. By using Simulgel FL, the lotions could be prepared using a cold process (without heat). The physicochemical properties (appearance, pH, viscosity) of the stable lotions were satisfactory. All prepared lotions possessed weak acidic pH values with pseudoplastic flows. Using modified Franz diffusion cell and synthetic membrane, the release rates of vetiver oil were relatively lower than those of citronella oil.