Aim – Evaluation of the irritant potential – OLEAMULS WS
Primary objective
The primary objective of this study is to assess the irritant potential of a cosmetic product.
Primary endpoints:
• Erythema (qualitative endpoint)
• Oedema (qualitative endpoint)
STUDY CHARACTERISTICS
Study design
The patch test was performed.
The product’s safety was evaluated by analysing the results obtained following the application of the product to the skin with a suitable device.
Sample size
Taking into account the type of the product being analysed and the objective of the trial, maximizing the certainty of the result the number of subjects to be recruited for the study was set* at 27, assuming:
– a clinically relevant difference of pre-post patch erythema/oedema of at least 0,5 with a standard
deviation of 0,6 such as to indicate that the substance is irritating;
– a type I error α of 0,01;
– a power of 95%.
*The sample size was calculated using the software G* power version 3.1.9.2
Eligibility criteria
The subjects who participated in the study were assessed under medical supervision and recruited in accordance with the following inclusion criteria:
• normal skin;
• women and men;
• age between 18 and 60;
• primary endpoint variables erythema and oedema with grade “absent: 0”;
• absence of known chronic and/or acute conditions/absence of mental and/or cognitive disorders;
• absence of skin and allergy conditions (related to cosmetics or other specific excipients) or other conditions (like irritation reactions of an unknown origin);
• absence of ongoing treatment with medicinal products that could affect the test’s outcome;
• non participation in other clinical studies in the previous 30 days;
• informed consent.
and the following exclusion criteria:
• pregnancy/breastfeeding.
Trial scheme
STEP 1 RECRUITMENT of subjects, carried out in accordance with the eligibility criteria.
STEP 2 BASELINE EVALUATIONS of the primary endpoints, at T0 before the application of the product.
STEP 3 CLEANING of the skin area intended for the test (skin of the back), with a 70% alcohol solution.
STEP 4 DILUTION, depending on the type, the product was applied diluted 1/10.
STEP 5 APPLICATION of the product, 20 μl/mg using a finn chamber for a time period of 48h.
STEP 6 NEGATIVE CONTROL, by 20 μl of physiological water.
STEP 7 REMOVAL of the finn chamber and evaluation of the primary endpoints after 15 minutes (T015), one hour (T1) and after 24 hours (T24).
Endpoints
• Qualitative endpoints: Erythema/Oedema (clinical evaluation by direct visual analysis)
The variables were evaluated by the professionals responsible for the trial in accordance with the following assessment scale:
Data and statistical analysis
The sample data of the qualitative endpoints have been described using the usual measures of location and dispersion: median and interquartile range. In addition, the absolute frequencies of the ratings expressed at each observation time were summarised.
For every endpoint variable, therefore, the assessments recorded at the follow-up times were examined and conclusions were drawn with regard to the trial’s outcome, according to the following criteria:
1. In the event of absence of erythema and/or oedema at any of the follow-up times, the product must be considered NOT IRRITATING.
2. In the event of appearance of very slight:1 or slight:2 erythema and/or oedema at intermediate times and absence of erythema and/or oedema at the time of the final observation (T24, 24 hours after the patch was removed), the product must be considered NOT IRRITATING.
3. In the event of appearance of very slight:1 or slight:2 erythema in J 6* subjects at the time of the final observation (T24, 24 hours after the patch was removed), the product must be considered NOT IRRITATING.
4. In the event of appearance of moderate:3 or marked:4 erythema and/or oedema in one or more subjects, at any of the follow-up times, the product must be considered IRRITATING; consequently, the clinical trial is concluded with a NEGATIVE OUTCOME.
5. In the event of appearance of very slight:1 or slight:2 erythema in > 6* subjects at the time of the final observation (T24, 24 hours after the patch was removed), the product must be considered IRRITATING, consequently, the clinical trial is concluded with a NEGATIVE OUTCOME.
6. In the event of appearance of oedema in one or more subjects at the time of the final observation (T24, 24 hours after the patch was removed), the product must be considered IRRITATING, consequently, the clinical trial is concluded with a NEGATIVE OUTCOME.
*The conclusions were drawn following the application of suitable non-parametric paired data tests (Wilcoxon signed-rank test/Sign test) to fictitious datasets. The analyses were performed using RStudio Version 1.4.1106 © 2009-2021 RStudio, PBC.
