Mechanical, optical, and physicochemical properties of HPMC-based doxazosin mesylate orodispersible films

Abstract In this study, orodispersible films formed from hydroxypropyl methylcellulose (HPMC) E6 (2, 2.5, and 3%) and plasticizers ((glycerin (Gly), propylene glycol (PP), or polyethylene glycol (PEG)), containing doxazosin mesylate, were prepared by the solvent casting method and characterized. Design of experiments (DoE) was used as a statistical tool to facilitate the interpretation of the experimental data and allow the identification of optimal levels of factors for maximum formulation performance. Differential scanning calorimetry (DSC) curves and X-ray powder diffraction (XRPD) diffractograms showed doxazosin mesylate amorphization, probably due to complexation with the polymer (HPMC E6), and the glass transition temperature of the polymer was reduced by adding a plasticizer. Fourier transformed infrared (FTIR) spectroscopy results showed that the chemical structure of doxazosin mesylate was preserved when introduced into the polymer matrix, and the plasticizers, glycerin and PEG, affected the polymer matrix with high intensity. The addition of plasticizers increased the elongation at break and adhesiveness (Gly > PEG > PP), confirming the greater plasticizer effect of Gly observed in DSC and FTIR studies. Greater transparency was observed for the orodispersible films prepared using PP. The addition of citric acid as a pH modifier was fundamental for the release of doxazosin mesylate, and the desirability formulation had a release profile similar to that of the reference product

Morphological alterations in human skeletal muscle cells exposed to di-(2-Ethylhexyl) Phthalate (dehp) in primary cell culture conditions / Alteraciones morfológicas en células musculares esqueléticas humanas expuestas a Ftalato de di-(2-etilhexilo) (dehp) en condiciones de cultivo celular primario

SUMMARY: Di-(2-ethylhexyl) phthalate (DEHP) is among the most common plasticizer additives that humans are in contact with daily. DEHP can be released from plastic and enter the human body, whereby it is metabolized and transformed into oxidative hydrophilic molecules. Clinical follow-ups in patients exposed to this phthalate and investigations in cultures of several cell types have provided information on its effects. For example, it is associated with inhibition of diploid human cell development and morphological changes in cultured germ cells. Although skeletal muscle represents around 50 % of the human body mass, knowledge about the effects of DEHP on this tissue is poor. Cultured skeletal muscle cells were exposed to DEHP (1 mM) for 13 days with the aim of exploring and evaluating some of the potential morphological effects. Three culture development parameters and nine cell characteristics were monitored during the bioassay. At 13 days, growth area, cell viability, and concentration of total proteins were lower in DEHP exposed than in control cells. Cell width and area, as well as the diameter of the nucleus and nucleolus, were greater in exposed cells than in control cells. These are interpreted as signs of cytotoxicity and suggest potential adverse effects on the development of skeletal muscle cells from DEHP exposure, as reported for other cell types.

RESUMEN: Diariamente los seres humanos tenemos contacto con aditivos plastificantes, el di-(2-etilhexil) ftalato (DEHP) se encuentra entre los más comunes. El DEHP puede liberarse del plástico e ingresar al cuerpo humano, donde es metabolizado y transformando en moléculas hidrofílicas oxidativas. Seguimientos en pacientes expuestos a este ftalato e investigaciones en cultivos de varios tipos celulares han aportado información sobre sus efectos. El DEHP es asociado con la inhibición del desarrollo de células humanas diploides y cambios morfológicos en células germinales en cultivo. Sin embargo, aún es poco lo que se sabe sobre los efectos en el músculo esquelético, a pesar de que este tejido representa alrededor del 50 % de la masa corporal del humano. Para explorar y evaluar algunos efectos morfológicos en células de músculo esquelético, cultivos primarios fueron expuestos a DEHP (1 mM) durante 13 días. Se dio seguimiento a tres parámetros de desarrollo del cultivo y nueve características celulares. Al término de 13 días de exposición, los valores del área de crecimiento, viabilidad celular y concentración de proteínas totales fueron inferiores con respecto a los cultivos control. Se observaron cambios morfométricos en las células expuestas. Particularmente, el ancho y área celular, así como los diámetros del núcleo y nucleolos, fueron mayores a los registros en las células control. Estos resultados se interpretan como signos de citotoxicidad y sugieren efectos potencialmente adversos en el desarrollo de las células del músculo esquelético ante una exposición al DEHP, como se ha registrado para otros tipos celulares.

An overview of preparation and characterization of solid binary system and its application on transdermal film with variation of plasticizers

Chemotherapy induced nausea and vomiting (CINV) and post-operative nausea and vomiting (PONV) is a problem, often occurs in patient. Inspite of high bioavailability, the demerits such as: hepatic first pass metabolism and invasive nature of oral and parenteral dosage forms can be avoided with anti-emetic therapy of transdermal device. The major objective of the present study is to modify the hydrochloride (HCl) form of Ondansetron (OND) to the base form followed by improvement of solubility and permeability of OND by employing solid dispersion (SD) loaded patches. Preformulation study, as observed, begins with an approach to enthuse solubility of OND by SD technique choosing different carriers. The choice of carriers was rationalized by phase solubility study. Several combinations of transdermal films were prepared with pure drug, carriers and SDs with plasticizer Ka values of OND-HPßCD binary system were found lower (54.43 to 187.57 M-1) than that of OND-PVP K-30 binary system (1156.77 to 12203.6 M-1). The drug content of SDs and patches were found satisfactory. Better permeation rate (236.48±3.66 µg/3.935 cm2) with promising flux enhancement (8.30 fold) was found with DBP loaded SD patch (P6*). Hence, enhancement of solubility and permeability of P6* ensures that it can successfully enhance the bioavailability

Films Based on Blends of Polyvinyl Alcohol and Microbial Hyaluronic Acid

Abstract The aims of this work were to produce hyaluronic acid (HA) by Streptococcus zooepidemicus ATCC 39920 in a low cost sugarcane molasses fermentation medium and to employ the produced HA to obtain films blends based on polyvinyl alcohol (PVA). The films were produced using solution casting method and they were characterized according to their microstructure, mechanical and barrier properties. HA was added in different concentrations (0, 5, 10 and 15% (w/w)), and glycerol was used as a plasticizer (25 g/100 g solids). All formulations resulted in easily manipulated films with good appearance. The addition of HA on PVA films increased their thermal stability, solubility, swelling index, water vapor permeability and elongation. Microbial HA sample combined with PVA showed to be a promising material to biomedical application, and an addition between 5 and 10% (w/w) was sufficient to improve PVA films properties.

Experimental Study on Migration Parameters of DEHP in PVC Infusion / 中国医疗器械杂志

The work explored the DEHP migration parameters in PVC infusion in clinic,based on the previous research on the test model of DEHP migrated from PVC infusion,to assess the safety of PVC infusion.The leaching solution samples in different conditions were evaluated by analysis of the DEHP in leaching solution using GC-MS under simulated clinical transfusion way.The release behavior of DEHP was significantly affected by the storage time,storage temperature,surrounding temperature,dripping speed,sterilization process,volume of the leaching solution,and the property of the leaching solution.

Di(2-ethylhexyl) phthalate-induced toxicity and peroxisome proliferator-activated receptor alpha: a review

The plasticizer di(2-ethylhexyl) phthalate (DEHP) has been widely used in the manufacture of polyvinyl chloride-containing products such as medical and consumer goods. Humans can easily be exposed to it because DEHP is ubiquitous in the environment. Recent research on the adverse effects of DEHP has focused on reproductive and developmental toxicity in rodents and/or humans. DEHP is a representative of the peroxisome proliferators. Therefore, peroxisome proliferator-activated receptor alpha (PPARα)-dependent pathways are the expected mode of action of several kinds of DEHP-induced toxicities. In this review, we summarize DEHP kinetics and its mechanisms of carcinogenicity and reproductive and developmental toxicity in relation to PPARα. Additionally, we give an overview of the impacts of science policy on exposure sources.

Application and Safety Evaluation of DEHP in PVC Medical Devices / 中国医疗器械杂志

DEHP is largely used in soft PVC products as the plasticizer, which is also widely applied in medical devices. Due to its potential and widespread toxicity and medical devices' specific use, the safety of DEHP's application in medical devices has received extensive attention. In this paper, a comprehensive review of the application and potential toxicity of DEHP in PVC medical devices is made on the basis of the research results all over the world. Besides, the safety evaluation in medical devices is discussed and some possible coping strategies are explored.

Research on Experimental Model of Security Assessment of DEHP Migration from PVC-Tubes Medical Devices / 中国医疗器械杂志

As we all know, DEHP is seriously harmful to human health and consequently has been acquired critical attention. DEHP is able to migrate from PVC medical devices for the non-chemically bound to PVC, thus contact with user and patient. The DEHP migration is influenced by various parameters. In order to assess the security of PVC-tubes medical devices scientifically of DEHP migration, we develop an experimental model by analyzing the parameters comprehensively and systematically, taking into account the clinical practices. For example, assessing the security of DEHP migration from infusion sets by utilizing this model.

Environmental Pollution and Diabetes / 임상당뇨병

Endocrine disrupting chemicals (EDCs) are exogenous chemicals contained in industrial substances and plasticizers commonly utilized worldwide. Human exposure to such chemicals, particularly at low-doses, is omnipresent, persistent, and occurs in complex mixtures. EDCs include bisphenol A, phthalates, pesticides, and persistent organic pollutants such as polychlorinated biphenyls. Burgeoning epidemiological, animal, and cellular data link environmental EDCs to metabolic dysfunction. In the last three decades, the number of diabetic patients has drastically increased worldwide, with current statistics suggesting that the number will double in the next two decades. There is epidemiological and experimental evidence linking background exposure to a selection of environmental EDCs with diabetes and impaired glucose metabolism. EDC may be related to increased risk of diabetes.

Complete genome sequence of a phthalic acid esters degrading Mycobacterium sp. YC-RL4

ABSTRACT Mycobacterium sp. YC-RL4 is capable of utilizing a broad range of phthalic acid esters (PAEs) as sole source of carbon and energy for growth. The preliminary studies demonstrated its high degrading efficiency and good performance during the bioprocess with environmental samples. Here, we present the complete genome of Mycobacterium sp. YC-RL4, which consists of one circular chromosome (5,801,417 bp) and one plasmid (252,568 bp). The genomic analysis and gene annotation were performed and many potential genes responsible for the biodegradation of PAEs were identified from the genome. These results may advance the investigation of bioremediation of PAEs-contaminated environments by strain YC-RL4.

Hypospadias induced by maternal exposure to di-n-butyl phthalate and its mechanisms in male rat offspring / 中华男科学杂志

Objective@#To induce hypospadias in male rat offspring by maternal exposure to di-n-butyl phthalate (DBP) during late pregnancy and further investigate its mechanisms.@*METHODS@#We randomly divided 20 pregnant rats into a DBP exposure and a control group, the former treated intragastrically with DBP while the latter with soybean oil at 750 mg per kilogram of the body weight per day from gestation days (GD) 14 to 18. On postnatal day (PND) 1, we recorded the incidence rate of hypospadias and observed the histopathological changes in the genital tubercle of the hypospadiac rats. We also measured the level of serum testosterone (T) by radioimmunoassay and determined the mRNA and protein expressions of the androgen receptor (AR), sonic hedgehog (Shh), bone morphogenetic protein 4 (Bmp4) and fibroblast growth factor 8 (Fgf8) in the genital tubercle by real-time PCR and Western blot.@*RESULTS@#No hypospadiac male rats were found in the control group. The incidence rate of hypospadias in male offspring was 43.6% in the DBP-treatment group. Histological analysis confirmed hypospadiac malformation. The serum testosterone concentration was decreased in the hypospadiac male rats as compared with the controls (［0.49 ± 0.05］ vs ［1.12 ± 0.05］ ng/ml, P <0.05). The mRNA expressions of AR, Shh, Bmp4 and Fgf8 in the genital tubercle were significantly lower in the hypospadiac male rats than in the controls (AR: 0.50 ± 0.05 vs 1.00 ± 0.12, P <0.05; Shh: 0.65 ± 0.07 vs 1.00 ± 0.15, P <0.05; Bmp4: 0.42 ± 0.05 vs 1.00 ± 0.13, P <0.05; Fgf8: 0.46 ± 0.04 vs 1.00 ± 0.12, P <0.05), and so were their protein expressions (AR: 0.34 ± 0.05 vs 1.00 ± 0.09, P <0.05; Shh: 0.51 ± 0.07 vs 1.00 ± 0.12, P <0.05; Bmp4: 0.43 ± 0.05 vs 1.00 ± 0.11, P <0.05; Fgf8: 0.57 ± 0.04 vs 1.00 ± 0.13, P <0.05).@*CONCLUSIONS@#Maternal exposure to DBP during late pregnancy can induce hypospadias in the male rat offspring. DBP affects the development of the genital tubercle by reducing the serum T concentration and expressions of AR, Shh, Bmp4 and Fgf8 in the genital tubercle, which might underlie the mechanism of DBP inducing hypospadias.

The effect of formulation additives on the properties of films prepared using Terminalia randii Baker F Gum

Background: Natural polymers are becoming useful excipients in pharmaceutical formulations due to their non-toxic and biodegradable properties. One of their common uses is in the manufacture of polymeric films.Objective: This present work is to evaluate the effect of plasticizer type and polymer type on the properties of Terminalia films.Method: Films were prepared by solvent casting method using Terminalia, xanthan gums and hydroxylpropy lmethylcellulose (HPMC). Terminlia was also combined with xanthan, HPMC at different ratios using propylene glycol and glycerol as plaasticizers. The films were characterized using adherence, folding endurance and mechanical properties were determined using tensile strength and percent elongation. Disintegration was carried out in a disintegration apparatus using distilled water, 0.1M HCl (pH 1.2) and phosphate buffer pH 6.8.Result: Films prepared with Terminalia and those prepared by combining Terminalia and xanthan gums showed adherence. Films plasticized with glycerol had higher folding endurance and tensile strength. When HPMC was combined with Terminalia, the disintegration of the films produced was significantly (p<0.05) reduced at pH 6.8Conclusion: Glycerol plasticizer produced films with optimal properties, while combination of Terminalia gum and HPMC, produced films with optimal properties. Therefore, plasticizer and polymer must be carefully chosen for film formulations

Risk assessment of di(2-ethylhexyl) phthalate in the workplace

OBJECTIVES: A hazard assessment of di(2-ethylhexyl) phthalate (DEHP), a commonly used workplace chemical, was conducted in order to protect the occupational health of workers. A literature review, consisting of both domestic and international references, examined the chemical management system, working environment, level of exposure, and possible associated risks. This information may be utilized in the future to determine appropriate exposure levels in working environments. METHODS: Hazard assessment was performed using chemical hazard information obtained from international agencies, such as Organization for Economic Cooperation and Development-generated Screening Information Data Set and International Program on Chemical Safety. Information was obtained from surveys conducted by the Minister of Employment and Labor (“Survey on the work environment”) and by the Ministry of Environment (“Survey on the circulation amount of chemicals”). Risk was determined according to exposure in workplaces and chemical hazard. RESULTS: In 229 workplaces over the country, 831 tons of DEHP have been used as plasticizers, insecticides, and ink solvent. Calculated 50% lethal dose values ranged from 14.2 to 50 g/kg, as determined via acute toxicity testing in rodents. Chronic carcinogenicity tests revealed cases of lung and liver degeneration, shrinkage of the testes, and liver cancer. The no-observed-adverse-effect level and the lowest-observed-adverse-effect level were determined to be 28.9 g/kg and 146.6 g/kg, respectively. The working environment assessment revealed the maximum exposure level to be 0.990 mg/m³, as compared to the threshold exposure level of 5 mg/m³. The relative risk of chronic toxicity and reproductive toxicity were 0.264 and 0.330, respectively, while the risk of carcinogenicity was 1.3, which is higher than the accepted safety value of one. CONCLUSIONS: DEHP was identified as a carcinogen, and may be dangerous even at concentrations lower than the occupational exposure limit. Therefore, we suggest management of working environments, with exposure levels below 5 mg/m³ and all workers utilizing local exhaust ventilation and respiratory protection when handling DEHP.

Dietary Exposure to Benzyl Butyl Phthalate in China / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>Benzyl butyl phthalate (BBP) is a plasticizer used in food contact materials. Dietary exposure to BBP might lead to reproduction and developmental damages to human. The present paper was aimed to assess the health risk of BBP dietary exposure in Chinese population.</p><p><b>METHODS</b>The BBP contents were detected in 7409 food samples from 25 food categories by gas chromatography-mass spectrometry operated in selected ion monitoring (SIM) mode. The dietary exposures of BBP in different age and sex groups were estimated by combining the content data with food consumption data derived from 2002 China National Nutrient and Health Survey, and evaluated according to the tolerable daily intake (TDI) of BBP established by European Food safety Agency.</p><p><b>RESULTS</b>It was found that BBP was undetectable in most samples and the highest level was 1.69 mg/kg detected in a vegetable oil sample. The average dietary exposure of BBP in people aged ⋝2 years was 1.03 μg/kg bw per day and the highest average exposure was found in 2-6 years old children (1.98 μg/kg bw per day). The BBP exposure in 7-12 months old children excessed 10% of tolerable daily intake (TDI) in worst scenario. .</p><p><b>CONCLUSION</b>The health risk of BBP dietary exposure in Chinese population is low and, considering BBP alone, there is no safety concern.</p>

Approaches to develop PLGA based in situ gelling system with low initial burst

In situ gelling systems have gained much interest owing to their successful application in the preparation of controlled drug delivery and tissue engineering. The commonly used polymer for these systems is the biocompatible and biodegradable polymer of Poly [lactic-co-glycolic acid] [PLGA] that is available in the market as implants, microparticles and in situ implant. A polymeric solution is prepared by mixing the polymer with a biocompatible solvent which may be water miscible such as N-methyl pyrrolidone [NMP], 2-pyrrolidone and Dimethyl sulfoxide [DMSO] or partially water miscible solvents such as triacetin, benzyl benzoate, ethyl acetate, triethyl citrate and benzyl alcohol. Upon injection of this polymeric solution into buffer or physiological fluid, the system solidifies and the administered drug releases in a controlled manner. The major drawback of these systems is their high initial burst that characterized by release of a noticeable amount of the administered drug during the first release stage that usually results in drug toxicity and tissue irritation. This review focuses on presenting the different strategies utilized to decrease the initial burst from PLGA in situ gelling system

Determination of Plasticizer DEHP Released from Medical Injection Equipment / 中国医疗器械杂志

To established an effective GC-MS /MS method for the contents determination of the residual DEHP in injection equipment, and investigate the effect of the pretreatment on the measurement. To simulate the clinical conditions of use, under the condition of 37 degrees C balance extraction, extract liquor by chloroform extraction, then the extract followed by analysis of GC-MS /MS. The method was simple, rapid, sensitive and accurate. The limits of quantitation (LOQ, S/N = 5) of cyclohexanone was 0.075 μg/mL, The spiked average recoveries ranged from 92% to 98%. The relative standard deviations (RSDs) of the method ranged from 1.01% to 1.61%, The method was simple, fast, sensitive and accurate, and may serve as a mass control method for residual DEHP in injection equipment.

Phthalate exposure and childhood obesity

Phthalates are commonly used as plasticizers and vehicles for cosmetic ingredients. Phthalate metabolites have documented biochemical activity including activating peroxisome proliferator-activated receptor and antiandrogenic effects, which may contribute to the development of obesity. In vitro and in vivo studies suggest that phthalates have significant effects on the development of obesity, especially after prenatal exposure at low doses. Although few studies have examined the effects of phthalate on obesity development in humans, some work has shown that phthalates affect humans and animals similarly. In this paper, we review the possible mechanisms of phthalate-induced obesity, and discuss evidence supporting the role of phthalates in the development of obesity in humans.

Exposure risk assessment of plasticizer in dietary food in Xiamen / 中华预防医学杂志

<p><b>OBJECTIVE</b>To understand the dietary consumption of residents in Xiamen and the content of phthalic acid esters (PAEs) in food, and to assess the plasticizer exposure risk of diet in Xiamen.</p><p><b>METHODS</b>The survey was conducted by stratified cluster random sampling method in Xiamen from September to October in 2010. According to the Xiamen administrative division, six neighborhood communities were selected as sampling units, then 25 families were randomly chosen from each sampling units.From the above 150 families, the permanent residents over the age of six were permitted to our study. The survey included 495 residents totally. These participants' information, such as basic personal information, physical activity levels, meal frequency and the average consumption of 33 kinds of food in 13 categories were collected using questionnaires. Thirteen categories included cereal and tubers, beans, vegetables, fungi and algae, fruits, dairy products, meat, seafood, eggs, snacks, beverages, cooking oil and spices. The height and weight of residents were measured and the average daily dietary intake was calculated. Thirty-three kinds of food in 13 categories were collected in supermarkets in Xiamen. According to the annual sales ranking, the top three-five brands of each kinds of food were selected and numbered, then two or three brands were chosen by random number table method from them; three completely individual packed samples in the same batch of each brand were detected; 243 samples were included in our study.100-500 g solid samples or 100-500 ml liquid samples were collected. The content of diethyl phthalate (DEP), dibutyl phthalate (DBP), di (2-ethylhexyl) phthalate (DEHP) in food were detected by liquid chromatography mass spectrometry, which expressed by median (minimum-maximum). The exposure dose, contribution rate and risk index of PAEs were calculated by point estimation method.</p><p><b>RESULTS</b>According to the average daily dietary intake of residents in Xiamen, the top three ones in 13 categories of food were cereal and tubers (337.16 g/d, 18.21%), vegetables (309.12 g/d, 16.69%) and fruits (213.20 g/d, 11.51%). The content of DEP, DBP or DEHP among different categories of food was significantly different (χ² values were 58.05, 50.19 and 102.10, P < 0.01). Among 13 categories of food, seafood contained the most DEP (0.090 (0.000-0.324)mg/kg); cooking oil had the most DBP (0.700(0.000-2.980) mg/kg) and DEHP (5.115(0.000-24.160) mg/kg). DEP, DBP and DEHP exposure(0.19, 4.20, 18.10 µg × kg⁻¹ ×d ⁻¹)in dietary food in Xiamen were less than the reference dose(RfD) (800, 100, 20 µg × kg⁻¹ × d⁻¹) proposed by the United States Environmental Protection Agency (EPA), and the risk indexes were 0.02%, 4.20% and 90.50%, respectively. Among 13 categories of foods, seafood was the main source of DEP dietary exposure. The exposure dose and contribution rate of DEP in seafood were 0.18 µg × kg⁻¹ × d⁻¹ and 94.74%, respectively.Vegetables were the main source of DBP and DEHP dietary exposure. The exposure dose and contribution rate of DBP and DEHP were 1.48 µg × kg⁻¹ × d⁻¹, 35.24% and 6.07 µg × kg⁻¹ × d⁻¹, 33.54%, respectively.</p><p><b>CONCLUSION</b>The food consumed by residents in Xiamen was overall in a safe state, but to some extent, there still exists DEHP exposure risk in foods.</p>

HPLC method to determine DEHP released into blood from a disposable extracorporeal circulation tube / 生物医学工程学杂志

We used blood as leaching medium, simulating clinical operation under maximum condition, to develop Liquid-phase extraction- High Performance Liquid Chromatography (HPLC) method for determination of plasticizer Di-(2-ethylhexyl)phthalate (DEHP) released from Disposable Extracorporeal Circulation Tube in order to lay the foundation of risk analysis of this product. The characteristic wavelength of DEHP in methanol was detected. Acetonitrile was added to the leaching blood in proportion and extracted DEHP from blood. The methodology for HPLC to quantify DEHP was established and the DEHP amount released from this disposable extracorporeal circulation tube was measured. The experiments showed good results as follows. The characteristic wavelength of DEHP was 272nm. The concentration of DEHP (5-250 microg/mL) kept good linear relationship with peak area (r=0.9999). Method sensitivity was 1 microg/mL. Precisions showed RSD<5%. The adding standard extraction Recovery Rates of 25, 100 and 250 microg DEHP standard were 61.91 +/- 3.32)%, (69.38 +/- 0.55)% and (68.47 +/- 1.15)%. The DEHP maximum amounts released from 3 sets of this disposable extracorporeal circulation tube were 204.14, 106.30 and 165.34 mg/set. Our Liquid-phase Extraction-HPLC method showed high accuracy and precision, and relatively stable recovery rate. Its operation was also convenient.

Role of IL-10 in the Trimellitic Anhydride-induced Contact Dermatitis / 체질인류학회지

Trimellitic anhydride (TMA) is widely used industrially to make epoxy and alkyd resins, plasticizers and surfactants. The purpose of this study was to investigate whether contact dermatitis is induced by repeated TMA challenge and the role of interleukin (IL)-10 in the TMA-induced contact dermatitis. The repetition of the challenge enlarged the extent of an early and a late phase of contact dermatitis in IL-10(+/+) and IL-10(-/-) mice. In the late phase of TMA-induced contact dermatitis, the peak of ear swelling responses by single challenge showed at 12 h after challenge, but the peak was observed at 8 h after repeated challenge. In the IL-10(-/-) mice, the repetition of the TMA challenges enlarged the extent of the contact dermatitis, but less than those in IL-10(+/+) mice. These results indicate that mice sensitized by TMA could possibly offer a useful model to study the mechanism of contact dermatitis, and IL-10 may act as potential modulators in the TMA-induced contact dermatitis. IL-10 may provide therapeutic tools for the treatment of TMA-induced contact dermatitis.