Characterization and release kinetics of nicotinamide microemulsion-based gels.

The aim of this study was to investigate physicochemical characteristics and to determine in vitro release kinetics of prepared nicotinamide microemulsion-based gels (MBGs). Nicotinamide microemulsions (ME) were composed of 3% w/w nicotinamide, 7% w/w water, 25% w/w soybean oil, and 65% w/w of 9:1 oleth-10:isopropyl alcohol mixture. A water-in-oil (w/o) type ME was converted to three MBGs. ME was combined with 5% w/w of colloidal silica to obtain MBG-1, with 5% w/w of 0.5% w/w carbomer solution to obtain MBG-2, or with a mixture of 3% w/w of 0.5% w/w carbomer solution and 2% w/w of PEG-40 hydrogenated castor oil to obtain MBG-3. The results indicated that MBG-1 was a clear gel with plastic flow while MBG-2 and MBG-3 were turbid gels with Newtonian flow. MBG-1 was physically and chemically stable at 4°C as well as at ambient temperature (approximately 30°C) during the 2-month study period. The color darkened when stored at 60°C. The release kinetics of MBG-1 was best fitted to zero order model. The in vitro release of nicotinamide from MBG-1 through cellulose membrane was compared with that from the ME and an oil-in-water (o/w) commercial cream (CC). The rank order of release rate of nicotinamide from different formulations was MBG-1 > ME > CC.

Microemulsions and nanoemulsions: novel vehicles for whitening cosmeceuticals.

For Asian women, white skin is preferable. During the last decade, skin whitening products appear to be the largest and continually growing segment in skin-care market in Asia and have an impaction of economic worth. Skin whitening or lightening agents are as cosmetics which act as a drug-like benefit since melanin producing process of the skin is disturbed and can be classified as cosmeceuticals. To increase efficiency, novel vehicles are necessary for skin penetration enhancement of these agents. Microemulsions and nanoemulsions are one of useful nanocarriers for skin application in view of achieving efficiency of the active substances. Moreover, they can be formulated with ease for active ingredient incorporation, high stability and good appearance. In this review article, applications of well-known whitening or lightening agents were summarized. In addition, the use of microemulsions and nanoemulsions as novel vehicles for whitening products were discussed.