Alcoholic SP (SP-ALC) was composed of SP, hydroxyethyl cellu- lose, propylene glycol and methyl paraben in a base of deionized water. Briefly, 5 g of SP was dissolved in hydroxyethyl cellulose (5 g) and propylene glycol (10 g) for 10 min under stirring (300 rpm). 78.8g of water was then added to the solution under stirring (300 rpm) for an additional 5 min stirring. This was followed by the addition of the methyl paraben (0.2 g) and carbopol (1 g). This solution was then stirred for a further 10 min. The final solution was then neutralized by triethanolamine (about 10 drops) under stirring condition (500 rpm) to obtain the SP-ALC gel.