Effects of Stabilized Retinaldehyde on Aging Skin: A Split-Face Study

Overview

The goal of this clinical trial is to learn if retinaldehyde cream improves the appearance of aging skin in women aged 30 to 60 years. Retinaldehyde is a form of vitamin A that the skin can convert into retinoic acid, which is known to help with skin aging. The study tested two strengths of retinaldehyde cream: a stronger version with 0.1% retinaldehyde and a weaker version with 0.05% retinaldehyde. The main questions the study aimed to answer were: whether retinaldehyde cream improves skin hydration and reduces oiliness, whether it improves skin firmness and elasticity, whether it reduces wrinkles and improves skin texture, whether it reduces uneven skin tone and pigmentation, and whether the stronger 0.1% cream works better than the weaker 0.05% cream. Researchers compared the two cream strengths by applying them to opposite sides of the same face. The stronger 0.1% cream was applied to the left side and the weaker 0.05% cream was applied to the right side. This approach allowed researchers to compare the two strengths directly in the same person under the same conditions. 56 women with visible signs of aging skin took part in the study at the Medical University of Silesia in Poland. One participant left the study early due to skin irritation. The remaining 55 women completed all 24 weeks of the study. Participants apply the creams in the evening, starting with twice a week for the first 2 weeks, then increasing to 3 times a week in week 3 and 4 times a week in week 4, based on skin tolerance, for 24 weeks total. They also used a provided skincare routine every day, which included a lipid face cream, a cleansing lotion, and a sunscreen with SPF 50 to protect their skin during the study. Participants were assessed 3 times: before starting the creams, after 12 weeks of use, and after 24 weeks of use. At each visit, researchers measured skin hydration, oiliness, elasticity, firmness, wrinkle depth, skin density, skin color, and other skin properties using a range of specialized skin measurement tools. Neither the participants nor the researchers assessing outcomes knew which cream strength was applied to which side of the face.

This study investigated the effects of topically applied stabilized retinaldehyde (RAL) at two concentrations (0.1% and 0.05%) on aging skin in 56 women (55 completing the study) aged 30-60 years (mean age 44.25 ± 8.1 years) with visible signs of photoaging including fine lines, wrinkles, pigmentation disorders, seborrhea, and loss of skin firmness. A 24-week, double-blind, split-face design was employed. The 0.1% RAL formulation was applied to the left side of the face and the 0.05% formulation to the right side. Application frequency started with twice weekly for the first 2 weeks, increasing to three times per week in week 3 and four times per week in week 4, based on skin tolerance. Both formulations contained stabilized retinaldehyde encapsulated in a cyclodextrin-glycosaminoglycan complex to enhance stability and provide controlled transdermal delivery. The tested products were commercially available formulations provided by the study collaborator. All participants followed a standardized background skincare regimen consisting of a lipid cream, cleansing lotion, and SPF 50 sunscreen throughout the study period. Skin assessments were performed at baseline (T0), after 12 weeks (T1), and after 24 weeks (T2) using a multimodal diagnostic approach at the Department of Basic Biomedical Sciences, Faculty of Pharmaceutical Sciences, Medical University of Silesia. Biophysical measurements included stratum corneum hydration (Corneometer CM 825), sebum excretion rate (Sebumeter SM 815), and melanin and erythema indices (Mexameter MX 18). Structural assessments were performed using high-frequency ultrasound (DUB SkinScanner, 50 MHz) to evaluate skin density and epidermal thickness, and the Cutometer MPA 580 to assess skin viscoelasticity and elasticity parameters (R2, R5, R7, Q1, Q2). Wrinkle depth and surface parameters were evaluated using Antera 3D imaging. Optical and imaging assessments included colorimetric analysis of L\*, a\*, and b\* values (Antera 3D), hyperspectral imaging across 400-1000 nm spectral range (SPECIM IQ), and Gray Level Co-Occurrence Matrix (GLCM) texture analysis including contrast and homogeneity of standardized clinical photographs (Fotomedicus system). The study aimed to determine whether stabilized RAL induces measurable structural, vascular, spectral, and optical changes in aging skin, and to compare the dose-dependent efficacy of 0.1% versus 0.05% concentrations across all measured parameters. One participant withdrew from the study due to facial erythema and discomfort. No other serious adverse events were reported.