Formulation and usage regime approaches to improve retinol tolerance
563
Presented by: Mark O'Mahony
Whilst retinol is well-known to have beneficial effects on the appearance of photoaged skin, high concentrations are often associated with consumer tolerance issues due to retinol-associated irritancy. Despite this, there is a still a demand for high concentration retinol products due to their efficacy, and concentrations as high as 1% can be found on the market. There is a need therefore to understand more about the tolerance profiles of high strength retinol products and identify approaches to mitigate the potential for irritation as much as possible. We therefore aimed to compare the tolerance profiles of two high strength concentrations of retinol, a 0.3% (w/w) formulation and a 1% (w/w) formulation. In a second study, we then further assessed whether formulation design, regime guidance and the addition of a specialised supporting product could improve the tolerance profile.
We first recruited 218 female participants with age-related skin concerns to study one; a 6 week at-home tolerance study where one cohort (n=115) tested a 0.3% (w/w) retinol formulation and a second cohort (n=103) tested an identical 1% (w/w) retinol formulation. Both products contained retinol in an encapsulated form. Formulations were applied at night-time only, ramping up usage over the study period to eventual nightly use after 4 weeks. Participants were instructed to follow retinol application with their own night-time moisturiser, using this moisturiser even on evenings when retinol was not applied. All participants applied an SPF day cream each morning.
We followed this up with a second study; an 8-week consumer tolerance study on 208 female participants with age-related skin concerns. This time applying a re-formulated 1% (w/w) retinol formulation; containing the same encapsulated retinol but with additional soothing and barrier supporting ingredients, followed by the application of a specially designed post-retinol soother product containing further barrier supporting and soothing ingredients. In this study participants ramped up usage of retinol more slowly over the study period, reaching nightly use on average after 6 weeks. The post retinol soother product was applied nightly throughout the study, even on evenings when retinol was not applied. All participants applied an SPF day cream each morning.
Participants self-reported whether they had any reactions to the retinol formulation and the severity of any reactions they had, using a classification guide developed by a Dermatologist. No reaction and mild reactions were deemed expected and tolerable based on participant feedback and expert Dermatologist and Toxicologist opinion. Therefore, the primary outcome measure was the percentage of participants in the reaction classification of ‘tolerant and mild’ as opposed to moderate or severe.
In study one, in the 0.3% retinol cohort (n=115) 69.6% of participants reported having no reaction and 19.1% reported having mild reactions, meaning 88.7% of participants were classed as ‘tolerant and mild’. In contrast, In the 1% retinol cohort (n=103) 39.8% of participants reported having no reaction and 22.3% reported having a mild reaction, meaning 62.1% were classed as ‘tolerant and mild’. In the 0.3% retinol cohort only 9.5% of participants reported moderate or severe reactions, compared with 37.9% in the 1% cohort.
In study two, in the cohort testing a re-formulated 1% retinol product with a post retinol soother product (n=208), 37% of participants reported having no reaction and 36.5% reported mild reactions, meaning 73.5% were classed as ‘tolerant and mild’. In this study 26.5% of participants reported moderate or severe reactions.
In conclusion, more participants in the 0.3% retinol cohort reported no reactions or only had mild reactions compared with participants in either of the 1% retinol cohorts. This suggests 0.3% is better tolerated than 1% retinol. However, a formulation re-design with soothers and barrier supporting ingredients, combined with the use of a post retinol soothing product and a slower ramp up as part of the regime, was able to improve the tolerance profile of 1% retinol. This study suggests that retinol concentration has arguably the biggest impact on consumer tolerance to retinol, but that a combination of formulation design, the speed of ramp up and supporting products can impact how well tolerated a high strength retinol product will be.
We first recruited 218 female participants with age-related skin concerns to study one; a 6 week at-home tolerance study where one cohort (n=115) tested a 0.3% (w/w) retinol formulation and a second cohort (n=103) tested an identical 1% (w/w) retinol formulation. Both products contained retinol in an encapsulated form. Formulations were applied at night-time only, ramping up usage over the study period to eventual nightly use after 4 weeks. Participants were instructed to follow retinol application with their own night-time moisturiser, using this moisturiser even on evenings when retinol was not applied. All participants applied an SPF day cream each morning.
We followed this up with a second study; an 8-week consumer tolerance study on 208 female participants with age-related skin concerns. This time applying a re-formulated 1% (w/w) retinol formulation; containing the same encapsulated retinol but with additional soothing and barrier supporting ingredients, followed by the application of a specially designed post-retinol soother product containing further barrier supporting and soothing ingredients. In this study participants ramped up usage of retinol more slowly over the study period, reaching nightly use on average after 6 weeks. The post retinol soother product was applied nightly throughout the study, even on evenings when retinol was not applied. All participants applied an SPF day cream each morning.
Participants self-reported whether they had any reactions to the retinol formulation and the severity of any reactions they had, using a classification guide developed by a Dermatologist. No reaction and mild reactions were deemed expected and tolerable based on participant feedback and expert Dermatologist and Toxicologist opinion. Therefore, the primary outcome measure was the percentage of participants in the reaction classification of ‘tolerant and mild’ as opposed to moderate or severe.
In study one, in the 0.3% retinol cohort (n=115) 69.6% of participants reported having no reaction and 19.1% reported having mild reactions, meaning 88.7% of participants were classed as ‘tolerant and mild’. In contrast, In the 1% retinol cohort (n=103) 39.8% of participants reported having no reaction and 22.3% reported having a mild reaction, meaning 62.1% were classed as ‘tolerant and mild’. In the 0.3% retinol cohort only 9.5% of participants reported moderate or severe reactions, compared with 37.9% in the 1% cohort.
In study two, in the cohort testing a re-formulated 1% retinol product with a post retinol soother product (n=208), 37% of participants reported having no reaction and 36.5% reported mild reactions, meaning 73.5% were classed as ‘tolerant and mild’. In this study 26.5% of participants reported moderate or severe reactions.
In conclusion, more participants in the 0.3% retinol cohort reported no reactions or only had mild reactions compared with participants in either of the 1% retinol cohorts. This suggests 0.3% is better tolerated than 1% retinol. However, a formulation re-design with soothers and barrier supporting ingredients, combined with the use of a post retinol soothing product and a slower ramp up as part of the regime, was able to improve the tolerance profile of 1% retinol. This study suggests that retinol concentration has arguably the biggest impact on consumer tolerance to retinol, but that a combination of formulation design, the speed of ramp up and supporting products can impact how well tolerated a high strength retinol product will be.