Test models to measure visible effects of lotion on skin: protection, healing, and dryness
Many absorbent consumer products incorporate lotions on the surface to improve overall consumer comfort. Manufacturers need to develop ways of measuring the potential effects of lotioned products in order to select formulations that will deliver the desired benefit. This investigation evaluates three established test models for their utility in evaluating the potential benefits of lotioned feminine protection pads.
The upper arm patch test model was used to examine the potential effects of lotions to prevent irritation. Lotions were evaluated by pretreating test sites with: a) different concentrations, or b) formulation variations, then patching with an irritant (0.5 percent sodium lauryl sulfate, or SLS). The modified Forearm Controlled Application Test (FCAT) was used to evaluate the healing effects of lotion on skin that had been compromised via a 24-h occluded patch with 0.1 percent SLS. Compromised test sites were swiped with feminine protection pads with lotion on the surface. The Behind-the-Knee (BTK) test model was used to determine the effects of increasing concentrations of lotion on dryness from feminine protection products. Effects were evaluated by visually assessing erythema and dryness, and measuring transepidermal water loss (TEWL).
In the upper arm patch test model, pretreatment with lotion partially prevented irritation from a subsequent treatment with SLS in a dose dependent manner, as demonstrated by lower overall means for erythema and TEWL. Formulation variations were equally effective in preventing irritation. In the modified FCAT, one treatment with lotioned pads demonstrated a healing effect by reducing dryness produced by the SLS patch. The second treatment reduced both dryness and erythema. TEWL was unaffected. In the BTK, the resulting degree of dryness at the test sites was inversely proportional to the amount of lotion on the feminine protection pad.
Each model, upper arm patch, modified FCAT, and BTK, has potential for detecting visual skin benefits from the use of lotion on absorbent products.
A growing trend for absorbent consumer products such as facial tissues, feminine protection products, baby diapers and incontinence protection, is to incorporate lotions on the surface to improve overall consumer comfort during product use. To consumers, the presence of a lotion means softer feeling skin, and the absence of unpleasant sensations, such as tightness. Such benefits are subjective, and developing ways to evaluate these benefits in a more objective manner presents a challenge to product manufacturers.
Lotions consist primarily of emollients to soften and humectants to hydrate skin. Most of these ingredients are well known with a long history of safe use. Nevertheless, consumer product manufacturers conduct skin compatibility programs to ensure the products are mild to skin under the conditions of use and potential misuse scenarios. An example of such an overall program has been reviewed (1, 2). This program evaluated a feminine protection pad with a novel foam core and emollient coating. The program included standard patch testing, 21-day cumulative irritation patch testing to assess the potential for developing skin irri ...