Specific dermatological benefits associated with quantities of lotion transferred to the skin

Summary

Background

A growing number of manufacturers are taking advantage of the ability of absorbent consumer products to deliver lotion to the skin. The lotion is included on these products to help protect the skin from adverse skin effects that can occur, including: 1) irritation, 2) over hydration of the stratum corneum, 3) dryness that can occur from extended exposure to highly absorbent consumer products and 4) changes in pH.

Objective

This manuscript presents results of a quantitative lotion transfer study of adult incontinence products. Resulting lotion transfer is compared to the results of several separate experiments in which specific skin benefits have been correlated to lotion concentrations.

Methods

The Behind-the-Knee (BTK) lotion transfer protocol was used to quantitate lotion transfer from adult incontinence (AI) test products constructed using 2 lotion formulations and two configurations of lotion application. A modified arm patch protocol, in which skin sites of a measured dimension were pre-treated with specific volumes of lotion, was used to evaluate protective effects of lotion against exposure to irritants, and over hydration from wetted absorbent products.

Results

After a 6-hr continuous exposure in the BTK the five-stripe lotion configuration products transferred (adjusted mean ± SE) 94 ± 11 μg/cm₂ to 104 ± 11 μg/cm₂ lotion. After 24 hr of wear, transfer had increased to 127 ± 22 μg/cm₂ and 149 ± 24 μg/cm₂, respectively. The single-block configuration products transferred 289 ± 10 μg/cm₂ to 316 ± 10 μg/cm₂ (P = 0.04). Transfer after 24 hr of wear was 328 ± 23 μg/cm₂ and 472 ± 21 μg/cm₂, respectively (P < 0.0001). Several protocols were used to evaluate the concentration of lotion required to provide four specific skin benefits. In studies evaluating protection against irritants, skin site pre-treated with lotion were patched with 0.5% SLS. Protective effects were assessed by visual assessment of erythema and trans-epidermal water loss (TEWL). In the first experiment, lotion pre-treatment concentrations as low as 165 μg/cm₂ exhibited significantly (P < 0.05) lower erythema and TEWL compared to the positive irritant control (i.e., no lotion pre-treatment and SLS only). In the second experiment, lotion pre-treatment concentrations of 80 μg/cm₂ (P = 0.018) exhibited significantly (P = 0.018) lower TEWL. In two studies on protection from over hydration, lotion pre-treatment sites were subsequently patched with wetted absorbent consumer products. The change in TEWL was used as a measure of over hydration. Lotion concentrations significantly reduced the increase in TEWL at 80 μg/cm2 (P = 0.007) and 70 μg/cm2 (P ≤ 0.05). A BTK study was used to evaluate the ability of lotion to prevent dryness. After 6 hours of wear, test products transferring lotion concentrations of 110 or 133 μg/cm₂ produced significantly lower scores for dryness compared to products transferring 48 or 69 μg/cm₂. Using collagen sheets to mimic the stratum corneum, an in vitro study was conducted to measure the ability of lotion to prevent passage of high pH buffer solution. Results demonstrated that the lowest concentration of lotion that was tested (110 μg/cm₂) interfered with passage of the high pH buffer through the collagen sheet, delaying the rise in pH.

Conclusions

We can conclude that pretreatment with 110 μg/cm₂ lotion acts as a barrier to high pH fluids such as urine. Using the measurement of lotion transfer from the AI products, together with the results of studies conducted to determine the concentration of lotion required to provide specific skin benefits, we conclude that the five-stripe lotion configuration AI test products transferred enough lotion (i.e, ≥ 80 μg/cm₂) to provide skin protection with regard to: 1) irritant effects and 2) excess moisture. The single-block AI test products also transferred enough lotion to provide these skin benefits (i.e., ≥ 165 μg/cm₂), and the additional benefits of skin protection against: 3) dryness, and 4) changes in pH.