Determination of SPF and Moisturizing Effects of Liposomal and Conventional Formulations of Octyl Methoxycinnamte as a Sunscreen

Objective To determine and compare the SPF (Sun Protection Factor) and moisturizing effects of the liposomal and conventional lotion formulations containing octyl methoxycinnamte (OMC) as a sunscreen by in vivo methods. Materials and Methods The multilamellar liposomes (MLVs) containing OMC were prepared by fusion method and o/w emulsion was prepared as FDA standard sunscreen method. The SPFs of the formulations were determined by in vivo method according to Australian standard. The exposure area was the back of ten volunteers. Subsites of the backs were exposed to solar simulator as ultraviolet (UV) source. The minimum erythemal dose (MED) for unprotected skin was observed in the next day. The sunscreen was spread (2 mg/cm2) over the area with a finger stall to achieve a uniform film. Each test subsite in a series was exposed to controlled amounts of simulated sunlight by a constant ratio. In the third day, the MEDs of the formulations were observed. The SPF was determined by the ratio between the time required to produce the minimal erythematous reaction by using sunscreen and the time needed to produce the same reaction without using sunscreen. The moisture content of the skin was determined after 30 min, 2, 3, 6 and 10 hours post-application of the formulations containing OMC and also NaCl 3% in eucerin (as a positive control) using Corneometer by measuring electrical capacitance. Results The SPF obtained from our in vivo results for standard Homosalate reference was almost the same as published SPF for this standard. The SPF of the liposomes containing OMC was a little bit more than lotion at the same concentration of OMC. All the tested formulations significantly increased the moisture content of the skin compared to control (without any treatment), in all the tested point times. After 30 minutes of post-application, the skin moisture content resulted from OMC-lotion was significantly more than liposomal-OMC and NaCl 3% in eucerin; however, 10 hours after post-application there were no significant differences in the skin moisture content of these three treatment groups. Conclusion MLV liposomes prepared by fusion method is a good vehicle for OMC as a sunscreen since it provides proper SPF and increase the moisture content of the skin.