Table VII Results of Contents and Diffusion Rate of PLO Gel in Niacinamide Site Sampling time (h) Detected quantity (μg) Penetration rate (%) Permeation rate (%) Receptor 2 6.65 ± 0.72 0.30 ± 0.03 22.62 ± 3.59 4 17.06 ± 0.51 0.47 ± 0.06 8 278.09 ± 97.26 12.52 ± 4.38 Membrane 8 224.38 ± 70.74 10.10 ± 3.19 PLO gel #2–1 - 2,221.08 - - The table shows the p-values of the coeffi cients and coeffi cients of each term of the skin permeation. The coef- fi cient with a negative value indicates each relationship with 2 and 4 h, that p-value was under 0.05 (p d 0.05). But 4 and 8 h coeffi cient and 2 and 8 h coeffi cient p-value were over 0.05 (*p 0.05). Using equat ion 3, coeffi cient was high in the order of poloxamer 407 C (0.1316), hydro- genated lecithin A (0.0649), and PEG-400 B (0.0047), implying that the main effect was signifi cant in the order of C, A, and B. Figure 13 d epicts the 3D response surface graph using a regression equation. Figure 13A is the graph that shows the effect of the amounts of hydrogenated lecithin and PEG-400 on DSC when a fi xed amount of poloxamer 407 was mixed in the formulated gels. This graph demonstrates that the amounts of hydrogenated lecithin and PEG-400 had no impact on DSC. Figure 13B displays the effect of the content of hydrogenated lecithin and poloxamer 407 on DSC when a fi xed amount of PEG-400 is mixed. This graph dem- onstrates that DSC increased with an increase in the content of hydrogenated lecithin and poloxamer 407. Figure 13C shows the effect of the amounts of poloxamer 407 and PEG- 400 on DSC when a fi xed amount of hydrogenated lecithin was mixed. This graph reveals that DSC showed an increase as the content of poloxamer 407 increased. The aforemen- tioned fi ndings suggest that the content of PEG-400 was found to have the most signifi - cant infl uence on DSC, followed by hydrogenated lecithin. PEG-400 seemed to have almost no impact. IN VITRO SK IN PERMEATION TEST The Franz d iffusion cell method was applied to measure in vitro diffusion study. To obtain the transdermal absorption rate of PLO gel, niacinamide was used as an indica- tor component. A trend line was drawn with HPLC measurement according to nia- cinamide concentrations, and the R2 value of the plotted points was one interpreted as greater reliability. Based on HP LC measurements, the skin permeation effi ciency of niacinamide in PLO gel was assessed using the following equation. In the evaluation of in vitro skin permeation effi ciency of PLO gel, the formulated PLO gel (#2–1) was chosen, and the experiment was repeated four times. Sampling of the receptor was conducted over time (2, 4, and 8 h) using the Franz diffusion cell method. The amount of niacinamide was quantifi ed via HPLC analysis by collecting the donor and the membrane after 8 h. Skin permeation ef- fi ciency (%) was calculated by substituting the quantifi ed values of each niacinamide concentration to equation 4. PREPARATION AND EVALUATION OF PLURONIC LECITHIN ORGANOGELS 343

2 3 1 +C × 100 C A= C (4) Ng C = Amount of niacinamide in original PLO gel , 1 Ng 2 = Amount of niacinamide in receptor , C Ng = Amount of niacinamide in membrane . C3 Th e sk in permeat ion effi ciency of the formulated PLO gel was calculated by substituting C1, C2, and C3 values obtained by HPLC analysis into the aforementioned equation. As a result, skin permeation effi ciency was 22.62±3.59% in the formulation #2–1, and this outcome reconfi rmed the applicability of the formulated PLO gel as a TDDS. CONCLUSION This study was performed to investigate the applicability of (PLO gel) in cosmetics as a topical drug delivery system. To achieve this objective, the formulation and assessment of PLO gel were conducted using RSM by mixing three major compositions, including lecithin, PEG-400, and poloxamer 407 prepared at different ratios. To evaluate the stability of PLO gel formulations, the elapsed time change was observed by storing these formulations at low temperature (4°C), room temperature (25°C), and constant temperature (45°C). The all-formulated organogels were stable at room and constant temperatures, but formulations #2–6 and #2–11 were unstable by exhibiting phase separation. To examine the pro perties of the formulated PLO gel, the relatively smooth and spread- able formulation #2–3 was measured using SEM, and this PLO gel exhibited a bicon- tinuous microemulsion structure. To determine gelation temperature exhibiting phase separation at low temperatures, DSC measurement was performed. To evaluate the char- acteristics of the gel formulations, elasticity and viscosity were also measured. RSM was used in an alyzing the measurements of elasticity, viscosity, and DSC varying depending on the content ratios of hydrogenated lecithin, PEG-400, and poloxamer 407 that have a signifi cant impact on the properties of the formulated PLO gel, and assessing the degree of infl uence of each composition. In the degree of infl uence on elasticity, the content of PEG-400 was most infl uential, followed by hydrogenated lecithin and polox- amer 407. In the degree of impact on viscosity, the amount of PEG-400 was most infl u- ential, followed by hydrogenated lecithin. The content of poloxamer 407 alone in the formulated gels appeared to have almost no effect, but had an infl uence to some extent in association with the other two compositions. In DSC analysis, the concentration of polox- amer 407 was most infl uential, followed by hydrogenated lecithin. The content of PEG- 400 seemed to have almost no effect. As previously intr oduced, PLO gel has shown problems by displaying fl owability at low temperatures issues have been raised concerning the safety of PLO gel in cosmetic formu- lations. This research has verifi ed the possibility of PLO gel as a safe formulation without fl owability at cold temperatures. In addition, skin permeation effi ciency was measured using the transdermal Franz diffusion cell system, and the measured value was 22.62±3.59%. This outcome demonstrated that PLO gel is suitable as a TDDS. JOURNAL OF COSMETIC SCIENCE 344