technicaltechnical Anti-inflammatory effects of sunscreens – wonder or science? by Staton J., Feng H. Dermatest Pty Ltd Sydney Australia Introduction measured using the mouse ear model, addition. rather than erythema of human skin. The suppression of sun-induced In March 2013, Sayer (5) submitted a Background erythema by addition of anti- Citizens Petition to the FDA, providing Actives used in sunscreens include a inflammatory “excipients” has been a evidence of such activity and proposing number cinnamates, benzophenones controversial issue with the attractiveness the removal of 5 sunscreen actives (from and salicylates (9). Chemicals with of this benefit claim countered by the FDA already depleted list of approved similar structures to these chemical questions of ethics. Some formulators chemicals). families of actives are recognized for of sunscreens have intentionally As none of these reports were based their anaesthetic activities. One active, incorporated ingredients with anti- on experimental design equivalent Trolamine salicylate, is also sold as an inflammatory properties into products to an internationally recognized SPF active in local anaesthetic creams (10). in the belief that this incorporation full panel test protocol (6), we set out Salicylic acid is a non-steroidal anti- will enhance the Sun Protection an experimental schedule in order inflammatory (NSAID). Factor (SPF) and/or act to reduce sun to investigate this potential, based Salicylates such as methyl salicylate induced inflammatory skin responses. on a combination of in vivo SPF and (Oil of Wintergreen) are traditionally Ingredients used with this objective erythemal regression methodology used as a counter irritant for soothing include Ammonium glycyrrhizinate and utilizing a high SPF commercial inflamed skin. Anti-inflammatory (1, 2), Chamomile extracts, aloe vera, formulation. activity of cinnamic acid esters has been and essential oils such as Tea tree oil. We firstly conducted an experiment, reported (11). Coutreau et al (3) have identified based on traditional In vivo SPF in order the potential anti-inflammatory to measure the impact of a commercial Experimental activity of α bisabolol, allantoin SPF 100 formulation (7), which In order the potential for the and 18-β-glycyrrhetinic acid based contained a high level of sunscreen commercial formulation (7), to express emulsions. actives (39%). We utilized the same SPF greater that expected SPF activity, an In Recently, Coutreau et al also reported 100 product in our experimentation vivo experimental protocol was devised (4) that anti-inflammatory activity, as was provided in the Sayer evidence which incorporated all of the principles measured as mouse ear oedema, was to FDA. This methodology is similar of the ISO SPF test (6) and, as well apparent in 13 of 21 actives tested at to that reported by Kolbe et al (8). In included more precise measurement up to their maximum (E.U.) permitted order to further qualify validate the of UV light induced erythemal concentration, suggesting that this may experimental design, a subsequent development. The objective of this impact on SPF, resulting in an artificially experiment was completed. For this, a study was to determine the efficacy of a higher In vivo value. However, these therapeutic anti-inflammatory active was test product in its erythemal regression findings are based on In vitro SPF testing added as a positive control and compared potential when topically applied product and with the anti-inflammatory activity with a reference sunscreen without this to the skin of human panelists following the science of beauty 57 stimulation of mild irritation by light. The Minimum Erythemal Dose Panelists were required to remain Ten test subjects were enrolled for (MED) necessary to induce a mild in the laboratory area for a period of 4 each of study. At recruitment, test erythemal response in each test hrs. At 4 hrs, visual, photographic and subjects were assessed for qualification participant was determined prior to spectrophotometric measurements were according to the ISO inclusion criteria commencement of the test. The target made of all exposed spots for each test for the study. Each completed and signed treatment area was identified for each site. an informed consent. The study was test subject. The areas were mapped Test subjects were instructed to return conducted according to Declaration for future reference. On the day of the to the test lab at 1, 5 and 18 days for of Helsinki guidelines. Individual test study, the product was applied to the further measurement (t=2, 3 & 4). At subjects were aged between 18 and 65 skin of the target sites at a rate of 2mg/ all visits, test subjects were instructed to and were of Fitzpatrick Skin Type I to III cm2 according to the schedule set out in remain passively seated in a controlled (ITA values > 20°). Race was Caucasian Section 2. environment with the test area of or Asian (first or second generation in Test sites were delineated for each the back exposed until their skin was Australia). challenge patch series of UV light considered to have stabilized. Visual A Solar Simulator was used to induce exposures. Reference SPF 15 sunscreen assessments were made and the erythema a mild erythema (Minimal Erythemal was applied to sites 3 and 4 at a rate of scored on by an expert, according to the Dose “MED”) on designated areas of the 2mg/cm2. A delay of 15 minutes was Standard Scalar Ratings. back of test subjects. The experimental then completed. A Solar Simulator [0] = 0 = no erythema present principles were consistent with those Model 16S was used to apply a series of [--/+] = 1 = minimal faint (light pink), normally applied for the measurement irradiation doses over all selected sites. uniform or spotty erythema of sun protection factor (SPF) and as Site 1: For the unprotected sites, this described in ISO 24444. The response was a series between 0.5 and 2 MED’s. [-/+] = 2 = mild erythema, pink post treatment with the product was Site 2: Immediately after irradiation uniform erythema covering most of observed and compared with positive and the clinician applied the SPF 100 test contact site negative controls as described below. Left product to the previously exposed skin at [-/++] = 3 = moderate erythema, pink/ to right randomization was applied. a rate of 2mg/cm2. The product was left red erythema visibly uniform in entire in place up to the 4 hr timepoint. contact area. Determination of Anti- Site 3. The exposures were SPF 8 (i.e. [+] = 4 = marked bright red erythema inflammatory effect of 0.5 X SPF 16), SPF 16, SPF 19 and SPF Commercial SPF 100 product 23. Following the irradiation, the SPF 15 [++] = 5 = severe deep red erythema. Site 1: Unprotected exposure – to product was removed by gentle wiping. The visual assessment of the erythema serve as negative control. Site 4: For the SPF 15 protected sites intensity was scored for each set of Site 2: Unprotected Exposure followed ,the exposures were SPF 8, SPF 16, SPF exposures. The score for the SPF 100 by SPF 100 – to assess anti-inflammatory 19 and SPF 23. Following the irradiation, treated spot was subtracted from the potential by sunscreen active. the SPF 15 product was removed by untreated in each case. gentle wiping and then the SPF 100 Site 3: ISO P2 Reference Sunscreen Results then exposure as a control for Site 4. product applied. The SPF 100 product Site 4: ISO P2 Reference Sunscreen was left in place up to the 4 hr time Results for visual assessments are then exposure, then remove P2 and point. shown in Fig. 1 and Fig. 2 below. apply SPF 100 imitated sunscreen use and erythemal development just beyond protection level, followed by additional sunscreen imitating re- application. The progression/ regression of erythema was evaluated at 1, 5 and 18 days, with the 4 hr post irradiation colour development being used as the baseline. One and the same assessor was used for each individual instrumental measurement throughout the study in order to rule out variations occurring from different gradings by different assessors Fig 1. MED Difference SPF 100 Treated vis Untreated – Visually Assessed 58 the science of beauty This represents not more that a minimal change in the reduction in erythemal response. Confirmation of Potential Activity Can we expect a mainstream therapeutic active to perform effectively if intentionally added to a sunscreen? In order to determine this, we conducted a further experiment in which the active hydrocortisone 17 butyrate was added to the same P2 sunscreen base as was used in the previous experiment. A further 10 Fig 2. Value Difference SPF 100 Treated applied over P2 SPF 16 Sunscreen vis P2 untreated – Visual Assessment. subjects were enrolled and the protocol for applications was as follows. Colour measurements were taken. overexposure over P2 sunscreen and Site 1: Unprotected exposure series The L*a*b* colour space values were then SPF 100 applied post radiation, the from 0.5 to 2 MED’s with Solar recorded. A Minolta Chromometer hand erythema was observed to be slightly less Simulator irradiation – to serve as base held spectrophotometer was utilized to for the SPF 100 treated spots. line control – exactly as per the ISO determine colour values and changes The Mean difference did not exceed 244444 SPF Protocol. versus the corresponding negative an a* value of 1 at any exposure time for Site 2: Unprotected Exposure as control (untreated) area. either the MED or P2 exposure series. above, followed by application of P2 Changes in skin condition were reported with the objective of quantifiably measuring Skin Colour: Tristimulus light values – shift in each component of L*a*b. values. – pigmentation colour reduction against the background indicates skin lightening. The L value gives the measurement of lightening of the spot, and the b* value is the yellow –blue component.