Regional variations in skin barrier function and cutaneous irritation due to iontophoresis in human subjects.

The effect of saline iontophoresis on skin barrier function and irritation was investigated on three body sites (abdomen, chest and upper arm) in order to select an appropriate site for iontophoretic delivery of drugs. Thirty healthy human volunteers were recruited according to specific entry criteria. Ten subjects, five males and five females, were assigned to each body site group. Skin barrier function and irritation was examined after 4 h of saline iontophoresis at a current density of 0.2 mA/cm(2) on a 6.5 cm(2) area in terms of the measured responses: transepidermal water loss (TEWL), skin capacitance, skin temperature and visual scores. Alterations in TEWL due to iontophoresis were not observed in the upper arm and chest; however, changes in TEWL at the abdomen were observed and returned to baseline 2 h after patch removal. Similarly, changes in capacitance due to iontophoresis returned to baseline (P>0.05) at the three body sites 2 h after patch removal except under the anode at the abdomen (P<0.05). There was a significant increase in skin temperature due to iontophoresis at the anode and the cathode (P<0.05) at the upper arm. Edema was not observed. At patch removal, the erythema score was significantly (P<0.001) elevated in comparison to baseline at the three body sites. Erythema resolved within 24 h except at the chest under the anode, where the erythema score was still higher (P<0.01) than the baseline. Papules appeared in five subjects at the active anode site on the chest. In three of the subjects, these papules did not resolve until 24 h post patch removal. Thus, there was regional variation in the function of the skin and irritation due to iontophoresis. Irritation was greater at the chest than at the abdomen or upper arm.     

The Effect of Saline Iontophoresis on Skin Integrity in Human Volunteers: I. Methodology and Reproducibility

This study, conducted in 36 human volunteers, was an evaluationof the effects of saline iontophoresis on skin temperature,irritation, and barrier function. The major objectives wereto assess the effects of low-level ionic currents, to validatethe proposed methodology of assessment, and to establish reproducibilityin repeated saline iontophoresis applications. This was thefirst of a multistage study designed to assess the safety of24-hr saline iontophoresis episodes at selected currents andcurrent densities. Since an iontophoresis patch challenges theskin harrier both by occluding the skin surface and by passingionic current through the skin, the experimental protocol wasdesigned to permit measurement of the contribution of each ofthese processes to the overall response. In this first stagewe investigated the effect of 10 min of current delivery, at0.1 mA/cm² on a 1-cm² area patch and 0.2 mA/cm² on a 6.5-cm²area patch compared to unpowered control patches. Twelve subjectswere tested under each condition on two separate occasions toexamine reproducibility of the response variable measurements.A further 12 subjects were tested once under the 0.2 mA/cm 6.5-cm2condition. Skin irritation was evaluated via repeated measurementsof transepidermal water loss, capacitance, skin temperature,skin color, and a visual scoring system, before the iontophoresisepisode and after patch removal. No damage to skin harrier functionin terms of skin-water loss or skin-water content was detected.Slight, subclinical, short-lasting erythema was observed forboth conditions. Assessment of correlation coefficients showedhighly statistically significant indications of reproducibilityfor all five response variables measured. The experimental design,in combination with a repeated measures analysis, provided clearseparation of the occlusion and ionic current components ofthe iontophoretic patch challenge. Further, the repeated measuresanalysis gave a highly sensitive assessment of skin irritationand resolution after patch removal. We conclude that the experimentalmethodology is appropriate for assessing possible changes inskin integrity resulting from saline iontophoresis under similaroperating conditions for longer durations and for other skinchallenges from which a subclinical response is expected.     

An in vivo investigation of the rabbit skin responses to transdermal iontophoresis

To optimize the benefits of transdermal iontophoresis, it is necessary to develop a suitable animal model that would allow for extensive assessments of the biological effects associated with electro-transport. Rabbit skin responses to iontophoresis treatments were evaluated by visual scoring and by non-invasive bioengineering parameters and compared with available human data. In the current density range 0.1–1.0 mA/cm² applied for 1 h using 0.9% w/v NaCl and 0.5 mA/cm² for up to 4 h, no significant irritation was observed. 2 mA/cm² applied through an area of 1 cm² for 1 h resulted in slight erythema at both active electrode sites but without significant changes in transepidermal water loss (TEWL) and laser Doppler velocimetry (LDV). A value of 4 mA/cm² under similar conditions caused moderate erythema at the anode and cathode with TEWL and LDV being significantly elevated at both sites; 1 mA/cm² current applied for 4 h, caused moderate erythema at both anode and cathode; and 1 mA/cm² applied for 1 h caused no irritation when the area of exposure was increased from 1 to 4.5 cm². When significant irritation and barrier impairment occurred, the erythema was resolved within 24 h with barrier recovery complete 3–5 days post-treatment. Rabbit skin thus shows promise as an acceptable model for iontophoresis experiments.     

Percutaneous absorption and skin irritation of JP-8 (jet fuel)

JP-8 is the major jet fuel used by US Army and Air Force. The purpose of the present study was to investigate the percutaneous absorption of JP-8 across pig ear skin and human skin in vitro and to study the effect of JP-8 exposure on the skin barrier function and irritation in Yucatan minipigs. JP-8 spiked with 5.0 microCi of radiolabeled (14C) tridecane, nonane, naphthalene or toluene (selected components of JP-8) was used for the in vitro percutaneous absorption studies with excised pig ear skin and human skin. For in vivo studies, 250 microl of JP-8 or two of its components (toluene or nonane) was placed in a Hill top chamber(R) and affixed over the marked treatment area for 24 h. Transepidermal water loss (TEWL), skin capacitance (moisture content) and skin irritation (erythema and edema) were evaluated before treatment and at 1,2 and 24 h after removal of the patches. The components of JP-8 such as tridecane, nonane, naphthalene and toluene permeated significantly through pig ear skin and human skin and the permeation rates were found to be proportional to their composition in JP-8. The steady state flux values of tridecane across pig ear skin and human skin did not differ significantly (P>0.05). Though the steady state flux values of nonane, naphthalene and toluene were statistically different between porcine and human skin (P<0.01), the values were close considering the large variations usually observed in the percutaneous absorption studies. Application of toluene, nonane or JP-8 increased the TEWL, JP-8 being the highest (3.5 times at 24 h compared to baseline level). The skin moisture content decreased after the application of JP-8, though it was not significantly different (P>0.05) from the baseline level. JP-8 caused a moderate erythema and a moderate to severe edema. Though the edema decreased after 24 h, the degree of erythema remained about the same until 24 h. The skin irritation caused by JP-8 was greater than neat toluene or nonane. The TEWL data of toluene, nonane and JP-8 correlated well with the skin irritation data (erythema and edema). Exposure of JP-8, which contains hundreds of aliphatic and aromatic hydrocarbons, caused significant changes in the barrier function of the skin as indicated by an increase in TEWL and produced a significant erythema and edema in minipigs. Furthermore, the disruption of barrier function of skin, as indicated by increased TEWL after exposure to JP-8 might result in increased permeation of its own components and/or other chemicals exposed to skin. The present study provides further evidence that pig ear skin may be used as a model for predicting the rates of permeation of chemicals through human skin.     

Dermal toxicity and microscopic alterations by JP-8 jet fuel components in vivo in rabbit

In this study, we investigated the skin irritation, macroscopic and microscopic barrier alteration in vivo in rabbits from aliphatic and aromatic components of jet propellant-8 (JP-8) jet fuel. Macroscopic barrier properties were evaluated by measuring transepidermal water loss (TEWL), skin capacitance, and skin temperature; microscopic changes were observed by light microscopy. Draize visual scoring system was used to measure skin irritation. We found significant (P<0.05) increase in temperature at the site of all chemically saturated patches immediately after patch removal in comparison to the control site. Tridecane (TRI) produced a greater increase in temperature and capacitance at all time points than all the other components of JP-8. Both the aliphatic and aromatic components increased the TEWL at all time points. Tridecane produced greater increase in TEWL followed by naphthalene (NAP), 1-methylnaphthalene (1-MN), 2-metylnaphthalene (2-MN), tetradecane (TET), and dodecane (DOD). All of the above components of JP-8 caused moderate to severe erythema and edema, which were not resolved to the baseline even after 24 h of patch removal. Light microscopy revealed an increase in epidermal thickness (ET), and decrease in length and thickness of collagen fibers’ bundle by the above components of JP-8. These results suggest potential dermatotoxicity from the JP-8 components.     

Percutaneous absorption and skin erythema: Quantification of capsaicin and its synthetic derivatives from gels incorporated with benzalkonium chloride by using non-invasive bioengineering methods

Nonivamide (NVA) and sodium nonivamide acetate (SNA) are synthetic derivatives of capsaicin. In this study, the cationic surfactant benzalkonium chloride was incorporated into the Carbopol 940® gel bases of capsaicin and its synthetic derivatives to evaluate the in vitro percutaneous absorption capacity. Afterwards, the optimal gel formulation selected from the in vitro study was used in a series of in vivo non-invasive bioengineering methods. To quantify the skin erythema and irritation caused by capsaicin, NVA, and SNA, laser Doppler flowmetry (LDF), transepidermal water loss (TEWL), and colorimetry were utilized for determining the cutaneous blood flow and skin barrier impairment to assess the level of irritant reaction. In the in vitro transdermal study, the gel base with 0.05% benzalkonium chloride possessed the highest penetration capacity: this was chosen for the in vivo study. After quantification of skin erythema by LDF, capsaicin developed more severe irritation than NVA, and SNA showed no skin irritation or pungent sensation in volunteers. The result of the TEWL experiment suggested that 0.05% benzalkonium chloride did not cause any skin impairment. Moreover, the Carbopol 940® gel base itself offered a moderate penetration capacity for drugs and avoided any skin irritation. The result of colorimetry confirmed that both Δa* and ΔE* parameters correlated well with the data of LDF and that they are good indicators of skin erythema response. After a series of in vivo applications, SNA was shown to be a potent analogue of capsaicin with a marked pharmacological effect and moderate percutaneous capacity and reduced skin erythema and painful sensation. Drug Dev. Res. 40:56–67, 1997. © 1997 Wiley-Liss, Inc.     

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.     

The effect of damaged skin barrier induced by subclinical irritation on the sequential irritant contact dermatitis

Skin damage caused by a single specific stimulus has been extensively studied. However, many additional mild skin irritants are experienced every day before obvious irritant contact dermatitis (ICD) appears. The effect that these previously experienced mild irritations have on the incidence and severity of sequential ICD remains undefined. The purpose of this work was to explore whether the effects of skin barrier damage induced by either the open patch test with 1% sodium lauryl sulfate (SLS), tape stripping test (TAP) (10×), or irradiation with 0.75 median erythemal dose UVB (MED) will affect the severity of sequential irritant dermatitis induced by a 0.5% SLS occlusive patch test (PT). Nine treatments were applied to nine different locations of the ventral forearm of each subject at random. The nine treatment types were as follows: open patch test with 1% SLS; 10× TAP; UVB irradiation with 0.75 MED; open patch test with 1% SLS + PT with 0.5% SLS (SLSPT); 10× TAP + PT with 0.5% SLS (TAPPT); UVB irradiation with 0.75 MED + PT with 0.5% SLS (UVPT); PT with distilled water (DISPT); PT with 0.5% SLS (PT); and the CONTROL (no treatment). After 5 days of subclinical irritation, the PT was applied on day 6. Transepidermal water loss (TEWL), capacitance (CAP), and skin color (a*) were measured at baseline and on days 6, 7, and 8. After the PT, indices of irritancy of PT, UVPT, SLSPT, and TAPPT were 60, 80, 87 and 100%, respectively. The index of irritancy of TAPPT and SLSPT were significantly higher than that of PT (p < 0.05). Clinical scores of SLSPT and TAPPT were also significantly higher than PT (p < 0.05). After 5 days of irritation, TEWL of SLS, TAP, SLSPT, and TAPPT were increased significantly compared to that of baseline. After the PT, D-value of TEWL between day 8 and day 6 ((≥6-8)TEWL) of SLSPT and TAPPT were greater than that of PT, and D-value of TEWL between day 8 and day 7 ((≥7-8)TEWL) of SLSPT and TAPPT were less than that of PT values. After the PT, a* values of SLSPT, TAPPT and PT all increased. The D-value of a* between day 8 and day 6 ((≥6-8)a*) of SLSPT and TAPPT were significantly greater than that of PT. After the PT, D-value of CAP between day 8 and day 6 ((≥6-8)CAP) of SLSPT was significantly different as compared to PT. The open patch test with 1% SLS and 10× TAP destroys the skin barrier and is able to significantly increase the irritancy and severity of sequential ICD by 0.5% SLS PT, and therefore influences the recovery speed of inflammation. The open patch test with 1% SLS, 10× TAP, and UVB irradiation with 0.75 MED affects the skin barrier to different degrees. TEWL is a sensitive biophysical parameter that can reflect mild damage to the skin barrier induced by subclinical irritation.     

Bacterial cellulose membranes as drug delivery systems: An in vivo skin compatibility study

Bacterial cellulose (BC) is a highly pure form of cellulose, produced in the form of a swollen membrane by several bacteria that demonstrated to be able to modulate the skin release of model drugs. In the present study, the skin irritation potential of BC was evaluated in human subjects. BC membranes with and without glycerin (acting as plasticizer) were tested. No significant differences were observed for transepidermal water loss (TEWL) measurements in comparison with negative control, 2 and 24 h after patch removal, which is an indicator of an absence of barrier disruption. Similar results were found for erythema. Clinical scores were zero at both times for all volunteers, with the exception of five volunteers that exhibited weak reactions. BC with glycerin provided a skin moisturizing effect statistically higher than the negative control (p = 0.044), which was not observed for BC alone. The good skin tolerance found after a single application under occlusion reinforces the putative interest of BC membranes as supports for drug topical delivery. Besides modifying the mechanical properties, the inclusion of glycerin results in a skin moisturizing effect which could be clinically relevant for the treatment for skin diseases characterized by dryness, such as psoriasis and atopic dermatitis.     

漆树叶皮肤刺激性与致敏性的实验研究

目的:研究漆树叶对动物的皮肤刺激性与致敏性。方法:采集新鲜漆树叶(不含叶轴)冻存后粉碎,室温下将漆树叶屑用蒸馏水制成糊剂,叶和水的比例为1:1。皮肤刺激实验:新西兰纯种家兔6只,脊柱两侧备皮(3cm×3cm)后,将漆树叶糊1.0g涂敷在左侧皮肤上,覆盖4h后清洗,右侧皮肤涂0.5ml蒸馏水作为对照。清洗后1、24、48、72h观察涂敷漆树叶糊部位皮肤反应并评分。皮肤致敏实验:白化豚鼠50只,分为实验组(20只,雌雄各半)、阳性对照组(20只,雌雄各半)和阴性对照组(10只,雌雄各半)。脊柱两侧备皮(2cm×2cm)。实验开始即刻和第7、14天时,实验组背部左侧备皮处涂敷0.8g漆树叶糊,阳性对照组涂敷2.5%2,4-二硝基氯苯0.2g,阴性对照组涂蒸馏水0.4ml,均覆盖6h后清洗;实验第28天时,实验组和阴性对照组豚鼠背部左侧备皮处涂敷0.8g漆树叶糊,阳性对照组涂敷1.0%2,4-二硝基氯苯0.2g,覆盖6h后清洗。其后24、48h分别计算致敏率、判定致敏程度。结果:皮肤刺激实验:有3只家兔在涂敷漆树叶糊后皮肤出现红斑,评分平均值为0.67分(24h),刺激反应程度为轻度。皮肤致敏实验:实验组与阴性对照组所有豚鼠涂敷漆树叶糊后24、48h均未出现红斑、水肿等反应,致敏反应积分平均值为0,致敏率为0,致敏程度为弱。阳性对照组豚鼠出现红斑、水肿,48h皮肤致敏反应总积分平均值为3.65分,致敏率为100%,致敏程度为极强。结论:漆树叶对实验动物皮肤有轻度刺激性,无致敏性。     

Short term study of human skin irritation by single application closed patch test: assessment of four multiple emulsion formulations loaded with botanical extracts

Background: Assessment of skin irritation potential is a major concern in safety assessment of cosmetics, when long-term use of these products are expected. Non-invasive bioengineering probes have been used previously to measure skin irritation potential of cosmetic ingredients.

Objectives: Experimentation carried out to weigh up the skin irritation potential of four multiple emulsion formulations via visual and non-invasive measurements. Immediate effects of formulations and comparison of two assessment techniques were also tried to establish.

Methods: Four multiple emulsion formulations one control (without botanical active) and three containing the functional botanical actives plus additives were tested in this study using the following techniques: transepidermal water loss (TEWL), COLIPA visual scoring method (CVSM), Mexameter MPA 5 (Courage + Khazaka, Germany) and capacitance [Corneometer MPA 5 (Courage + Khazaka, Germany)]. Visual examination and non-invasive measurements were performed at baseline and after 24?h. The formulations were applied on the forearm of 12 healthy volunteers of same sexes aged 20–25 years.

Results: We found that none of the formulation produced irritation both on visual and instrumental evaluation. However, formulations MeB and MeC have comparable immediate effects on dryness, erythema, melanin and TEWL. Formulation MeC produced more effective results on different parameters, may be due to synergistic effect of two extracts, while MeA failed to produce any immediate effects on skin parameters. Moreover results of both assessment methods are parallel to each other.

Conclusions: None of the formulation produce irritant effects, barrier impairment effects or immediate effects except for the formulation MeC which produced appreciable results than other formulations but statistically these results were insignificant (p?>?0.05). Based on these results, it could be concluded that formulations may be implied safely as skin rejuvenating candidates.     

滚轮微针处理次数对药物皮肤渗透、分布及皮肤刺激性的影响

目的 考察用于皮肤促透研究的滚轮微针处理次数。方法 以维A酸为模型药物,Franz扩散池、组织匀浆法研究裸鼠皮肤的促透效果,用亚甲蓝染色法、激光共聚焦显微镜法等考察裸鼠皮肤的药物分布,经皮水分流失（TEWL）测量法、激光多普勒血流量法评价皮肤刺激性。结果 滚轮微针处理次数为1、3、5、8、10次时,处理次数越多,促透效果越好,皮肤中滞留药量也越高,但是皮肤中滞留药量在处理8次和10次时无显著性差异（P>0.05）。亚甲基蓝染色和激光共聚焦实验均显示处理次数增加,针孔分布均匀度提高;亚甲基蓝染色显示,处理5次以上时,出现部分针眼重叠而皮肤破损现象。在体皮肤内药物吸收实验显示处理1次时,裸鼠皮肤中滞留药量均匀性较差,但是处理3次以上时,皮肤中滞留药量均匀性明显改善。TEWL测量法显示处理5次以下,皮肤屏障功能恢复时间为24 h,处理8次以上为36 h。激光多普勒血流量法显示处理5次以下,皮肤屏障功能恢复时间为1 h,处理8次以上为2 h。结论 滚轮微针处理5次可确保裸鼠皮肤促透研究的安全性和有效性。     

Effect of jet fuels on the skin morphology and irritation in hairless rats

Jet A and JP-8 are the major jet fuels used in civilian and military (US Air Force) flights, respectively. JP-8+100 is a new jet fuel recently introduced by US Air Force in some of its locations. The purpose of this study was to investigate the effects of dermal exposure of jet fuels (Jet A, JP-8, and JP-8+100) on the skin morphology, barrier function, moisture content, blood flow, and skin irritation (erythema and edema) in hairless rats. Jet fuels were applied by both occlusive and unocclusive methods. The skin of treated and control (untreated) sites were excised and analyzed by magnetic resonance imaging (MRI) (500 MHz, 11.7 Tesla). Unocclusive application of JP-8, Jet A, and JP-8+100 increased the transepidermal water loss (TEWL) gradually and the values at 120 h were significantly greater than the baseline value (P<0.05). Both occlusive and unocclusive application of jet fuels decreased the skin moisture content significantly (P<0.05). Unocclusive application of JP-8, Jet A, and JP-8+100 increased the skin blood flow, though the values returned to the baseline levels within 24 h. Occlusive application of jet fuels (8 h/day for 2 days) caused a substantial increase in the skin blood flow and the values at 48 h were about 6-fold greater than the baseline value. Occlusive application of jet fuels caused a moderate to severe erythema and a moderate edema. MRI was used to obtain proton images and water self-diffusion maps of hairless rat skin exposed to jet fuel. Exposure to JP-8 showed the largest difference from the control with regards to visual observations of the stratum corneum and hair follicles, while JP-8+100 appeared to affect the hair follicle region. The results of the present study demonstrate that exposure to jet fuels can disrupt the skin barrier function, cause skin irritation, and alter the skin structure (stratum corneum and viable epidermis) and MRI can be used as a tool to investigate the alterations in the skin morphology after exposure to toxic chemicals.     

Enhanced transdermal delivery of low molecular weight heparin by barrier perturbation

The purpose of this work was to investigate the in vitro transdermal delivery of low molecular weight heparin (LMWH). Hairless rat skin was mounted on Franz diffusion cells and treated with various enhancement strategies. Passive flux was essentially zero and remained low even after iontophoresis (0.065 U cm(-2) h(-1)) or application of ultrasound (0.058 U cm(-2) h(-1)). A significant increase in flux across tape stripped skin (4.0 U cm(-2) h(-1)) suggests the interaction of stratum corneum (SC) with LMWH which was confirmed using Differential Scanning Calorimetry and Fourier Transform-Infrared spectrophotometry. Maltose microneedles were then employed as a means to locally disrupt and bypass the SC. Transepidermal water loss (TEWL) and transcutaneous electrical resistance (TER) were measured to confirm the barrier disruption. Microneedles breached the SC resulting in increased TEWL, decreased TER and enhanced LMWH permeability (0.175 U cm(-2) h(-1)). Microneedles when used in conjunction with iontophoresis had a synergistic effect on LMWH delivery resulting in enhancement of flux by 14.7-fold as compared to iontophoresis used alone. Confocal laser scanning microscopy substantiated the evidence about LMWH interaction with SC. In conclusion, LMWH was shown to interact with SC and therefore tape stripping or microneedles dramatically increased its delivery due to disruption of the SC skin barrier.     

Assessment of skin irritation and molecular responses in rat skin exposed to nonane, dodecane and tetradecane

Aliphatic hydrocarbons constitute a major portion of jet fuels, kerosene and other solvents. This study investigated the effects of dermal exposures of selected aliphatic hydrocarbons (nonane, dodecane and tetradecane) on the skin irritation (erythema), transepidermal waterloss (TEWL) and expression of interleukin-1alpha (IL-1alpha), tumor necrosis factor (TNF-alpha) and monocyte chemoattractant protein-1 (MCP-1) in the skin and blood of hairless rats. Dermal exposures were carried out by occlusive application of chemicals (230 microl for 1 h, using Hill Top Chambers) for 1 h. The expression of IL-1alpha, TNF-alpha and MCP-1 was measured by enzyme immunoassay (EIA), and the regulatory proteins NFkappaB and IkappaBalpha were measured by Western blot analysis. The skin irritation and TEWL data indicate that the irritation was in the following decreasing order: nonane > dodecane > tetradecane. Likewise, nonane significantly increased the expression of IL-1alpha, TNF-alpha and MCP-1 in skin and blood as compared to control at different time points. Dodecane and tetradecane did not show any increase in the expression of IL-1alpha and MCP-1 as compared to control (P > 0.05), but the expression of TNF-alpha by dodecane and tetradecane was significantly higher than control at all time points. The release of cytokines by nonane exposure was further supported by activation of NFkappaB p65 and corresponding degradation of IkappaBalpha in the skin. In conclusion, this study demonstrates that the biophysical parameters (TEWL and erythema scores) were correlated to the biomarker expressions after dermal exposures with nonane but not with dodecane and tetradecane. Dodecane produced only mild irritation in response to experimental conditions of the present study and further did not show significant differences in IL-1alpha and MCP-1 levels in skin and blood. However, TNF-alpha was well expressed in response to all the chemicals. Tetradecane did not show any visible signs of skin irritation and also did not produce any significant difference in IL-1alpha and MCP-1 release profiles as compared with control. The expression of TNF-alpha in skin due to tetradecane support the fact that visually indistinguishable skin irritation reactions can induce significant changes in the biological marker profile.     

Human Dermal Safety Studies with Eflornithine HCl 13.9% Cream (Vaniqa™), a Novel Treatment for Excessive Facial Hair

Summary

Eflornithine HCl 13.9% cream (Vaniqa?) is a novel treatment for the management of unwanted facial hair in women. This paper reports the results of four modified open-label, within-subject vehicle-controlled studies evaluating the dermal safety of this topical treatment. In a repeated insult patch test (230 subjects), erythema with oedema occurred in 38.9% of subjects treated with eflornithine HCl 13.9% cream and 4.8% of subjects treated with vehicle cream. Challenge applications at previously untested sites following the three-week induction period produced noticeable erythema or greater on only four sites treated with eflornithine HCl 13.9% cream and one vehicletreated site. The erythema at these sites subsided substantially within 24 hours. In a three-week cumulative irritation study (30 subjects), the mean irritation score for sites treated with eflornithine HCl 13.9% cream was 1.33, compared with 0.76 at vehicletreated sites and 3.09 at positive-control (sodium lauryl sulphate-treated) sites (p < 0.001 between all three groups). In a phototoxicity study (25 subjects), irradiated sites showed either no reaction (40% of both sites treated with eflornithine HCl 13.9% cream and vehicle-treated sites), or mild erythema subsiding in all cases but one within 24 hours. No reaction was seen at non-irradiated sites. In a photocontact allergy study (30 subjects), challenge with eflornithine HCl 13.9% cream or its vehicle alone produced either no reaction or mild erythema subsiding within 24 hours at both irradiated and nonirradiated sites. No serious adverse events were reported during the studies, and the only adverse events considered related to treatment were pruritus (three subjects) and dry skin at test site (one subject). These results demonstrate that eflornithine HCl 13.9% cream does not have contact sensitising, photocontact allergic or phototoxic properties. It can cause irritation under exaggerated conditions of use. Eflornithine HCl 13.9% cream, therefore, has a favourable dermal safety profile appropriate for a topical treatment to be applied routinely.     

Percutaneous permeation and skin irritation of JP-8+100 jet fuel in a porcine model

JP-8 is the major jet fuel used by US Air Force. JP-8+100 is a new jet fuel recently introduced by the US Air Force, which contains JP-8 plus three performance additives [butylated hydroxytoluene (BHT), metal deactivator (MDA) and 8Q405]. The purpose of the present study was to investigate the percutaneous permeation of JP-8+100 across pig ear skin in vitro and to study the effect of JP-8+100 exposure on the skin barrier function, moisture content and irritation in Yucatan minipigs. The influence of performance additives on the permeation of JP-8 was studied by adding each additive individually to JP-8. The percutaneous permeation and skin irritation data obtained with JP-8+100 were compared with that of JP-8. JP-8+100 spiked with 5.0 microCi of radiolabeled [14C]tridecane, nonane, naphthalene or toluene (selected components of JP-8+100) was used for the in vitro percutaneous permeation studies. For skin irritation studies, 250 microl of JP-8+100 was placed in a Hill top chamber and affixed over the marked treatment area for 24 h. The components of JP-8+100 such as tridecane, nonane, naphthalene and toluene permeated readily through pig ear skin without any apparent lag time. Compared to JP-8, the permeation of tridecane, toluene and nonane from JP-8+100 was significantly lower (P<0.05). However, the permeation of naphthalene from JP-8+100 was significantly higher than from JP-8. When BHT was added to JP-8, the permeation of all four chemicals were significantly decreased (P<0.05). Though the addition of 8Q405 to JP-8 decreased the permeation of all four chemicals, the values were not significantly different (P>0.05) from that of JP-8. Addition of MDA did not show any significant change in the permeation of the selected chemicals from JP-8. Application of JP-8+100 increased the transepidermal water loss (TEWL) about three times compared to the baseline level. The skin moisture content decreased consistently after the application of JP-8+100, though it was not significantly different (P>0.05) from the baseline level. JP-8+100 caused a moderate erythema (score: 1.60) and a moderate to severe edema (score: 2.60). These results suggest that JP-8+100 produces significant changes in the barrier function of the skin and a local irritant effect upon occlusive dermal exposure. However there was no significant difference in the skin irritation data observed from JP-8 and JP-8+100.     

Porcine Ear Skin as a Model for the Assessment of Transdermal Drug Delivery to Premature Neonates

PURPOSE: The purpose of this study was (i) to validate differentially tape-stripped, porcine skin as an in vitro model for the evaluation of transdermal drug delivery (TDD) to premature neonates, (ii) to determine whether the model could estimate neonatal skin permeability as a function of postconceptional age (PCA), and (iii) to demonstrate that iontophoretic delivery permits precise control of drug input independent of skin barrier function. METHODS: Passive permeation of caffeine, phenobarbital, and lidocaine across tape-stripped porcine skin barriers was measured. Iontophoretic delivery of lidocaine across skins with different barrier competencies was also evaluated. RESULTS: For all drugs, passive permeation correlated with skin barrier function; that is, with transepidermal water loss (TEWL): Jss = A x exp[B x TEWL]. Combining this result with a previously derived dependence of TEWL upon the PCA of premature neonates in vivo allowed a relative value of Jss to be predicted for a given PCA. Comparison of these predictions showed excellent agreement with experimental data reported for diamorphine. Iontophoretic lidocaine delivery was precisely controllable independent of barrier competency. CONCLUSIONS: Porcine skin, in vitro, differentially tape-stripped to specific barrier competencies, is a useful model to explore TDD in premature neonates. The potential for iontophoresis to provide improved dose control and adjustment, irrespective of skin barrier maturity, is established.     

In vivo assessment of safety of microneedle arrays in human skin

Microneedle arrays are promising devices for the delivery of drugs and vaccines into or the skin. However, little is known about the safety of the microneedles. In this study we obtained insight in the ability of microneedles to disrupt the skin barrier, which was evaluated by transepidermal water loss (TEWL). We also determined the safety in terms of skin irritation (skin redness and blood flow) and pain sensation. We applied microneedle arrays varying in length and shape on the ventral forearms of 18 human volunteers. An effect of needle length was observed, as TEWL and redness values after treatment with solid microneedle arrays of 400mum were significantly increased compared to 200mum. The blood flow showed a similar trend. Needle design also had an effect. Assembled microneedle arrays induced higher TEWL values than the solid microneedle arrays, while resulting in less skin irritation. However, for all microneedles the irritation was minimal and lasted less than 2h. In conclusion, the microneedle arrays used in this study are able to overcome the barrier function of the skin in human volunteers, are painless and cause only minimal irritation. This opens the opportunity for dermal and transdermal delivery of drugs and vaccines.     

Human dermal safety studies with eflornithine HCl 13.9% cream (Vaniqa), a novel treatment for excessive facial hair

Eflornithine HCl 13.9% cream (Vaniqa) is a novel treatment for the management of unwanted facial hair in women. This paper reports the results of four modified open-label, within-subject vehicle-controlled studies evaluating the dermal safety of this topical treatment. In a repeated insult patch test (230 subjects), erythema with oedema occurred in 38.9% of subjects treated with eflornithine HCl 13.9% cream and 4.8% of subjects treated with vehicle cream. Challenge applications at previously untested sites following the three-week induction period produced noticeable erythema or greater on only four sites treated with eflornithine HCl 13.9% cream and one vehicle-treated site. The erythema at these sites subsided substantially within 24 hours. In a three-week cumulative irritation study (30 subjects), the mean irritation score for sites treated with eflornithine HCl 13.9% cream was 1.33, compared with 0.76 at vehicle-treated sites and 3.09 at positive-control (sodium lauryl sulphate-treated) sites (p < 0.001 between all three groups). In a phototoxicity study (25 subjects), irradiated sites showed either no reaction (40% of both sites treated with eflornithine HCl 13.9% cream and vehicle-treated sites), or mild erythema subsiding in all cases but one within 24 hours. No reaction was seen at non-irradiated sites. In a photocontact allergy study (30 subjects), challenge with eflornithine HCl 13.9% cream or its vehicle alone produced either no reaction or mild erythema subsiding within 24 hours at both irradiated and non-irradiated sites. No serious adverse events were reported during the studies, and the only adverse events considered related to treatment were pruritus (three subjects) and dry skin at test site (one subject). These results demonstrate that eflornithine HCl 13.9% cream does not have contact sensitising, photocontact allergic or phototoxic properties. It can cause irritation under exaggerated conditions of use. Eflornithine HCl 13.9% cream, therefore, has a favourable dermal safety profile appropriate for a topical treatment to be applied routinely.