Development of a sensitive test method to evaluate mechanical irritation potential on mucosal skin

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

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 2 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-hours continuous exposure in the BTK the 5-stripe lotion configuration products transferred (adjusted mean ± SE) 94 ± 11-104 ± 11 μg/cm² lotion. After 24 hours of wear, transfer had increased to 127 ± 22 and 149 ± 24 μg/cm² , respectively. The single-block configuration products transferred 289 ± 10-316 ± 10 μg/cm² (P = .04). Transfer after 24 hours of wear was 328 ± 23 and 472 ± 21 μg/cm² , respectively (P < .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% sodium lauryl sulfate (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 < .05) lower erythema and TEWL compared to the positive irritant control (ie, no lotion pre-treatment and SLS only). In the second experiment, lotion pre-treatment concentrations of 80 μg/cm² (P = .018) exhibited significantly (P = .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 = .007) and 70 μg/cm² (P ≤ .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 (ie, ≥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 (ie, ≥165 μg/cm² ), and the additional benefits of skin protection against: (3) dryness, and (4) changes in pH.

The influence of different shavers on the skin quantified by non-invasive reflectance confocal microscopy

BACKGROUND

The impact of personal care devices on skin is mainly assessed using subjective tools. However, new objective, accurate non-invasive in vivo imaging techniques have been developed. The aim of this study was to evaluate the ability of reflectance confocal microscopy (RCM) in quantifying morphological impact of shavers on skin. Furthermore, tape stripping (TS) as method to study morphological impact of shavers was evaluated.

METHODS

In 12 healthy male subjects, for two consecutive days, a split-face test was performed in the neck; on one side a shaver was applied, while the other side was exposed to TS. The stratum corneum (SC) thickness was quantified using RCM and sensory observations were evaluated using questionnaires.

RESULTS

Shavers with a different impact on skin, can be discriminated by RCM; shaver B removed more SC after application than the skin friendlier shaver A. Furthermore, the changes in SC thickness induced by TS corresponded well to that of the shavers.

CONCLUSION

RCM is able to quantify the impact of different shavers on skin. Besides, TS appeared to be a suitable model mimicking the mechanical impact of shavers on skin. RCM in combination with the TS model appeared to be a suitable minimally invasive model to obtain morphological and cell biological data on skin-material interactions caused by different personal care devices.

Assessing the dermal compatibility of a new female incontinence product line

CONTEXT

We have developed a line of products designed to better meet the overall needs of women suffering from urinary incontinence. The products are more discrete and contain a unique odor neutralizing technology (ONT).

OBJECTIVE

This paper describes the overall skin compatibility program for this product line in which the new products were compared to negative controls and/or commercially marketed reference products with an established history of safe use.

MATERIALS AND METHODS

Test products consisted of several product forms (light pads/pantiliners, moderate pads, briefs and taped diapers) with ONT and having various degrees of protection. Studies were conducted using standard protocols for 4-day and 21-day cumulative irritation, the Human Repeat Insult Patch Test (HRIPT), and the Behind-the-Knee (BTK) test for mechanical and chemical irritation. In one 4-day irritation study and one HRIPT, test subjects consisted of individuals with self-assessed sensitive skin. In addition, one 4-day study was conducted using normal skin sites, and sites compromised by tape stripping. Nonirritant controls were physiologic saline and/or current, commercially marketed incontinence products. All responses were evaluated by visual scoring of erythema. In addition, in the BTK, transepidermal water loss (TEWL) and adverse sensory effects collected from panelists' daily diaries were also evaluated.

RESULTS AND DISCUSSION

Two 4-day cumulative irritation studies and one 21-day study demonstrated that a wide range of product forms (liners, light and moderate pads, briefs and adult diapers) produced skin reactions similar to the nonirritant controls. The 4-day study conducted using sensitive skin subjects showed good skin compatibility, and the test products were comparable to the nonirritant controls. In the 4-day study with both normal and compromised skin sites, test products produced mean erythema scores similar to the nonirritant controls. Three HRIPT separate studies confirm that the products do not induce contact sensitization, including one study conducted on individuals with self-assessed sensitive skin. In the BTK, test and control products produced similar irritation, as assessed by erythema, TEWL and sensory effects.

CONCLUSION

The results from the patch tests and mechanical irritation test demonstrate good skin compatibility of the new line of products with the unique ONT. In addition, the forms of the product (i.e. liner, pad or brief), were equally compatible with skin.

A Feminine Care Clinical Research Program Transforms Women's Lives

Feminine hygiene products and menstruation education have transformed the lives of women throughout the world. The P&G Feminine Care Clinical Innovation Research Program has played a key role by expanding scientific knowledge as well as developing technical insights and tools for the development of feminine hygiene products. The aim has been to meet the needs of women throughout their life stages, advancing their urogenital health beyond just menstruation, as well as helping to understand the role of sex hormones in various important health issues that women face. This review article highlights key contributions and research findings in female hygiene products, urogenital health research, and method development. The clinical research team focused on utilizing the results of clinical safety studies to advance the acceptance of feminine hygiene products world-wide. Key findings include that perception of skin sensitivity is not limited to the facial area, but is also relevant to the body and the genital area. Also, they shed light on the role of estrogen in autoimmune diseases as well as premenstrual syndrome. Efforts in the method development area focused on innovative tools that are reliable, predictive of clinical trial results and capable of measuring wear comfort, genital skin health, and the impact of product use on the consumer’s quality of life. A novel method, behind-the-knee (BTK) test, developed to model irritation under normal wear conditions, was the first to account for both chemical and mechanical sources of irritation. The method has been accepted by the FDA as a substitute in clinical trials in some cases, and by American Society for Testing and Materials as a global standard test method. Additional proprietary methods were developed to enhance visual grading of irritation using cross-polarized light, to measure the amount of lotion transferred from sanitary pads, and to evaluate the skin mildness. Finally, the Farage Quality of Life tool was created to measure consumer’s well-being. Based on the results of this extensive clinical research and the newly developed testing methods, the changing needs of women throughout their life stages are better met.

Dermatological testing of an improved apertured film surface for feminine hygiene pads

CONTEXT

Apertured polyethylene films (AF) have been used as a surface for sanitary pads for decades because they are compatible with the skin and keep the pad surface drier. A modified film (AF-plus) with improved fluid handling and a smoother, suppler texture has been developed. We hypothesized that these changes would improve both performance and skin compatibility. However, distinguishing the skin effects of materials that are inherently mild is a challenge.

OBJECTIVES

(i) To compare the skin irritation potential of pads with AF-plus modified film relative to the standard AF film and (ii) to assess the potential for the AF-plus film to induce delayed contact hypersensitivity.

MATERIALS AND METHODS

Pads bearing the AF-plus film were compared to pads with the standard AF film in a behind-the-knee (BTK) test, which assesses the combination of chemical irritation and frictional effects of materials applied to the popliteal fossa under a semi-occlusive bandage. Erythema on the skin surface was scored with the naked eye and subsurface tissue erythema was visualized and scored using cross-polarized illumination. Skin dryness was scored with the naked eye only. One-sided statistical evaluations were performed to test the hypothesis of AF-plus film superiority. The potential of the AF-plus film to induce delayed contact hypersensitivity was assessed by a human repeat insult patch test (HRIPT).

RESULTS

Pads with the AF-plus surface were significantly milder to skin in the BTK test, producing lower levels of both surface and subsurface tissue erythema. Moreover, subjects with preexisting erythema on the skin surface at study start developed comparatively less erythema over the course of the study overall with the AF-plus pad compared to the AF pad. No significant difference in skin dryness was observed between product groups. The AF-plus pad showed no evidence of inducing delayed contact hypersensitivity.

CONCLUSIONS

The AF-plus pad was superior to the AF pad in terms of skin mildness as discerned by objectively scored surface and subsurface tissue erythema. In subjects with preexisting erythema, the AF-plus pad appeared to contribute less to the further development of inflammation under the test conditions. Given the compositional similarities in the two films, the results could point to more limited contribution of the AF-plus film to skin friction, one of the factors simulated by the BTK test protocol.

Assessing the skin irritation potential of facial tissues

Our primary objective was to develop a short-term test system for evaluating differences in the irritant effects of facial tissues that could be used as a screening tool for product improvements with regard to skin mildness. The strongest evidence for product superiority is based on a combination of data: 1) subjective (i.e., panelist or consumer preference with regard to the attributes important to skin effects) and 2) expert clinical evaluation (i.e., a quantitative measure of product superiority by a third party, such as erythema and dryness scores). In this assay, both measures were evaluated.

METHODS

In three separate studies, facial tissue products were compared with a currently marketed product with a lotion coating (product A). Test materials included products B and C (each without a lotion coating) and product G (a facial tissue product coated with a developmental lotion). Panelists (15-16 per study) were assigned one tissue product to use on one side of the nose and the other product on the alternate side. They were asked to wipe the tissue from the nasal bridge to the upper lip for 10 wipes every 20 minutes for a total of 170 wipes (17 series) daily on Monday through Thursday. Prior to the first test product application, the integrity of the skin on the nasolabial folds was compromised by tape stripping using successive applications of occlusive tape. Erythema and dryness were scored by a trained grader every morning and afternoon. Panelists were asked specific questions about product preference at the end of each day.

RESULTS

Based on the statistical analysis, the reported sensory effects were the most reliable measure of product differences, with panelists showing a clear preference for the lotioned product (A) over the nonlotioned products (B and C), and slight preference for product A over the other lotioned product (G). The clinical evaluation measures of irritation (erythema and dryness) were less consistent in detecting product differences. Those differences that were detected were generally consistent with the sensory effects data.

CONCLUSIONS

This assay detects significant panelists' preferences and, therefore, forms a useful part of the arsenal for evaluating skin effects and claims support. However, without further modification, the assay is not sufficiently robust to reliably detect differences in the clinical measures of irritant effects (erythema and dryness).

CORRELATING SENSORY EFFECTS WITH IRRITATION

The goal of this preliminary study was to examine data collected in the course of the development and conduct of the behind-the-knee (BTK) test for correlations between the objective scores of erythema and the sensory effects reported by the panelists. In addition, the intensity of physical characteristics of femcare products and prototypes was evaluated using the descriptive analysis panel (DAP) and results were compared to the BTK results to determine if certain physical characteristics of the products correlated to different sensations experienced by the BTK panelists. Test materials were commercially available or developmental catemenial products. In the BTK test, samples were applied daily to the area behind the knee and held in place for 6 hours per day for 5 consecutive days by an elastic knee band of the appropriate size. Irritation was graded 30-60 minutes after removal of each application. The DAP uses individuals trained to recognize and grade certain physical characteristics of products, including degree of plastic feel, scratchiness, glide, and cottony feel. In the BTK studies, the ability to differentiate between the test samples via reported sensory effects correlated with the ability to differentiate via objective scores for irritation in seven of 15 comparisons. A correlation between the magnitude of the irritation score, independent of the specific test sample, and reports of adverse sensory effects was observed in 13 of 15 comparisons. Two comparisons conducted in the BTK were also evaluated using the DAP. For one comparison, there was a clear difference in the product physical characteristics in the DAP that was consistent with mean erythema scores and reported sensory effects in the BTK. For the other comparison, there was no clear difference between the two products by either the DAP or the BTK.

Cutaneous and Sensory Effects of Feminine Hygiene Pads Among Women with Recent Genital Infection

We compared the skin compatibility of two menstrual pad technologies in a single-center, parallel, randomized, examiner-blinded study involving adult women. This report presents the results of a subset of 10 participants who had a genital infection within 12 months prior to the start of the study. In a blinded fashion, participants were randomized to receive one of the two pads for use over two menstrual periods. Participants' skin erythema was graded 24-48 hours following cessation of menstrual flow and on day 14 of each menstrual cycle. Participants subjectively reported any sensory effects. Vulvar erythema scores for the mons pubis, labia majora, labia minora, perineum, buttocks, left medial thigh, and right medial thigh assessed after both menstrual cycles were not statistically different between groups or between the two different products. A low incidence of itching and burning occurred in both groups without statistical significance; none of the participants experienced a recurrent or new genital infection. These preliminary results show that participants with recent genital infections included in clinical studies do not exhibit greater vulvar erythema or sensory effects than participants without recent genital infection. The study showed that the safety profile of the products tested remained acceptable in women with recent genital infection.

Evaluating lotion transfer to skin from feminine protection products

BACKGROUND/PURPOSE

Adding lotions or emollients to the surface of a variety of paper products improves overall consumer comfort. Techniques to measure lotion transfer to skin are needed.

METHODS

Two approaches were compared to assess lotion transfer from impregnated feminine pads: (1) pad application to the popliteal fosssa, an adaptation of the previously described 'behind-the-knee (BTK)' test model, and (2) a clinical in-use study in which pads were worn in the usual manner. In both approaches, dressings attached to the skin were used to absorb lotion transferred from the pad. Lotion transfer was first evaluated after 3 h in both protocols, and then after either 6 h (BTK method) or after and 24 h (clinical use test).

RESULTS

In the BTK model, lotion transfer was a function of both the total amount of lotion contained on the topsheet and the type of absorbent material in the core of the pad. Pads containing absorbent gelling material transferred lotion more effectively than pads containing cellulose absorbent cores. In the in-use clinical study, the results were directionally similar, but statistical significance was not reached.

CONCLUSIONS

An adaptation of the BTK test method provides an effective means of evaluating the transfer of lotion formulations from feminine protection pads.

Porcine Vagina Ex Vivo as a Model for Studying Permeability and Pathogenesis in Mucosa

The vaginal mucosa is commonly exposed to a variety of topical agents, including chemical contraceptives, drugs for the treatment of specific pathological conditions, and pathogenic microorganisms. In vitro models can provide important information regarding the penetration and efficacy of topical compounds as well as the pathogenesis of various diseases such a menstrual toxic shock syndrome. Realistic and reproducible test systems are important if new agents are to fulfill their therapeutic potential in human populations. The selection of appropriate animal species and tissue and the use of valid in vitro systems can avoid many of the shortcomings of current animal and cell culture test systems. This review provides information about the factors that should be considered when selecting the best model to study the permeability of the human vagina. The characteristics of an ex vivo porcine model are explored and the validity of this model is demonstrated in terms of its histology, ultrastructure and composition and organization of the permeability barrier; data indicate excellent correlation of permeability and tissue response between human and porcine vaginal tissue.

A Behind-the-Scenes Look at the Safety Assessment of Feminine Hygiene Pads

Forms of menstrual protection have evolved with time. Today's disposable feminine hygiene products, notably sanitary pads, include a wide range of designs and features to meet women's needs for reliable, discreet, and comfortable protection. Manufacturers support substantive research and testing programs to ensure the safety of these products. The premarket safety assessment of feminine hygiene pads is a systematic, stepwise process that includes toxicological evaluation of the raw materials, the conduct of prospective, controlled clinical trials to assess product safety-in-use, and, in some cases, independent scientific review. A broad clinical database, developed over the past 20 years, substantiates that modern, feminine hygiene pads are not associated with significant gynecological, dermatological, or microbiological effects. Postmarket surveillance provides reassurance that the products are acceptable to consumers worldwide.

The Behind-the-Knee test: an efficient model for evaluating mechanical and chemical irritation

BACKGROUND/PURPOSE

The 'Behind-the-Knee' method (BTK test), using the popliteal fossa as a test site, evaluates both the inherent chemical irritation, and the potential for mechanical irritation of substrates and products. This approach eliminates some of the difficulties of in-use clinical test systems while still providing reliable results. In this publication, examples of the results of BTK tests on several materials are presented with direct comparisons, where possible, with results of in-use clinical testing conducted on the same materials.

METHODS

In in-use clinical tests, volunteer panelists were provided with catamenial products to use in place of their normal product. In the BTK test, samples were applied daily to the popliteal fossa using an elastic athletic band. In both studies, irritation reactions were scored visually.

RESULTS

Levels of irritation in the BTK test are consistently higher than those of standard patch tests, illustrating the contribution of mechanical irritation to the overall irritant potential of materials and products. Repeated tests on identical test materials demonstrated that the BTK test results are reproducible. Side-by-side comparisons of the BTK test and in-use clinical tests demonstrated that the BTK test produces results of similar quality to the in-use clinical. By using several concurrent panels with a common test material, it is possible to compare the irritant properties of several materials at once.

CONCLUSIONS

We have tested over 25 different materials in over 35 BTK studies. The test method has proven reliable and versatile in testing a wide variety of materials, including menstrual pads, topsheets, interlabial pads, pantiliners, tampons and lotion coatings on products. Unlike in-use clinicals, the BTK test allows the direct comparison of two products at one time on the same individual, and is easily adapted to investigative programs. It is subject to fewer confounding factors, is much easier to implement, has a shorter turnaround time, and is less expensive than in-use clinical testing. Importantly, unlike standard patch tests, the BTK test evaluates both the inherent chemical irritation associated with materials and the mechanical irritation owing to friction. Although the BTK test was developed using catamenial products, the test system provides a valuable alternative for evaluating any material where mechanical irritation may play a role, including textiles, facial tissues, baby and adult diapers, and laundry products that may leave residues on fabrics.

The vulvar epithelium differs from the skin: implications for cutaneous testing to address topical vulvar exposures

Vulvar tissue is more permeable than exposed skin due to differences in structure, occlusion, hydration and susceptibility to friction. The safety assessment of products that contact the vulva should account for this potentially heightened permeability. Standard clinical patch tests may not sufficiently mimic vulvar exposures. Because testing on the vulva is not routinely feasible, we are investigating new and modified cutaneous test methods to increase the degree of conservatism of the safety assessment. To this end, we have 1) developed a method to assess chemical and frictional effects by means of repeated application to the popliteal fossa (the behind-the-knee test); 2) modified the quantitative risk assessment for the induction of allergic contact dermatitis; and 3) proposed a modified human repeat insult patch test for assessing materials intended for vulvar contact. Modification of the traditional 4-day, irritation patch test by using wet samples or compromized skin sites failed to enhance test sensitivity. Future studies will evaluate testing in subjects with heightened susceptibility to chemical and sensory irritation, in order to increase test sensitivity to chemical irritants. These approaches can be employed to augment the margin of safety when cutaneous test methods are applied to agents that contact the vulva.