|Full text PDF:||http://hdl.handle.net/10504/68742|
Dihydroxyacetone (DHA) is the primary ingredient in most sunless tanners. Lawsone is a primary component of red henna, used in henna tattooing and reversed tattooing. DHA initiates a reaction called the Maillard reaction which results in the browning of the skin. Application of lawsone results in the production of colored keratin-bound fluorescent polymers called melanoidins. DHA alone gives some protection in the UVA spectrum, with minimal UVB. When lawsone is applied after the application of DHA, a different set of melanoidins are produced, giving UVB and even greater UVA protection. In this study, a multiple emulsion (W1/O/W2) containing 0.035% (w/w) lawsone and 1% (w/w) DHA were prepared using the two step process by Matsumoto et al. The first step was the production of the primary (W1/O) emulsion. The primary emulsion, making up 40% of the final volume of the emulsion, was then added to the secondary aqueous phase (W2). A combination emulsion was prepared by combining doubled concentrations of lawsone and DHA multiple emulsions (W1/O/W2) in a 1:1 ratio through trituration. The structure of the multiple emulsions was determined by light and fluorescent microscopy. The stability of the prepared emulsions was characterized after storage at 25??C, 32??C, and 40??C and over a period of 28 days. DHA and DHA in combination showed a significant decrease in % entrapment efficiency to 37.41 ?? 6.03% and 5.41 ?? 3.82% after 28 at 40??C, showing physical/ chemical instability of emulsions at increased temperature. Chemical instability of the emulsions was confirmed by varying decrease in pH at 32??C and 40??C of DHA emulsion and combination emulsion. Structural instability of emulsions at 40??C was confirmed by increase of zeta potential and rheological tests using flow and oscillatory stress/time sweeps. No significant changes in particle size suggest no coalescence occurring. Spreadability remained within the range of ??? 20 cm??/g to 35cm??/g respectively. Characterization testing suggest the stability of lawsone and DHA emulsions were best when kept separate at 25??C. In vitro surface release and Franz diffusion studies verified and confirmed drug release were more effective when lawsone and DHA emulsions were kept separate.