Effect of saline iontophoresis on skin barrier function and cutaneous irritation in four ethnic groups.

The effect of saline iontophoresis on skin barrier function and irritation was investigated in four ethnic groups (Caucasians, Hispanics, Blacks and Asians). Forty healthy human volunteers were recruited according to specific entry criteria. Ten subjects, five males and five females, were assigned to each ethnic group. Skin barrier function was examined after 4 hours 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. There were significant differences in TEWL among the ethnic groups prior to patch application. TEWL at baseline in ethnic groups was in the rank order: Caucasian>Asian>Hispanic>Black. Iontophoresis was generally well tolerated, and skin barrier function was not irreversibly affected by iontophoresis in any group. There was no significant skin temperature change, compared to baseline, in any ethnic groups at any observation point. Edema was not observed. At patch removal, the erythema score was elevated in comparison to baseline in all ethnic groups; erythema resolved within 24 hours. Thus, saline iontophoresis produced reversible changes in skin barrier function and irritation in healthy human subjects.     

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.     

Transdermal Iontophoretic Delivery of Vapreotide Acetate AcrossPorcine Skin <Emphasis Type="BoldItalic">in Vitro</Emphasis>

Purpose The purpose of this study was to evaluate the feasibility of delivering vapreotide, a somatostatin analogue, by transdermal iontophoresis.Methods In vitro experiments were conducted using dermatomed porcine ear skin and heat-separated epidermis. In addition to quantifying vapreotide transport into and across the skin, the effect of peptide delivery on skin permselectivity was also measured. The influence of (1) current density, (2) pre- and post-treatment of the skin, (3) competitive ions, and (4) inclusion of albumin in the receptor on vapreotide delivery were investigated.Results Epidermis proved to be a better model than dermatomed skin for vapreotide transport studies. Despite the susceptibility of vapreotide to enzymatic degradation, a flux of 1.7 μg/cm² per hour was achieved after 7 h of constant current iontophoresis (0.15 mA/cm²). Post-iontophoretic extraction revealed that, depending on the experimental conditions, 80–300 μg of peptide were bound to the skin. Vapreotide was found to interact with the skin and displayed a current-dependent inhibition of electroosmosis. However, neither the pre-treatment strategies to saturate the putative binding sites nor the post-treatment protocols to displace the bound peptide were effective.Conclusion Based on the observed transport rate of vapreotide across porcine epidermis and its clinical pharmacokinetics, therapeutic concentrations should be achievable using a 15-cm² patch.     

In vitro and in vivo evaluation of a hydrogel-based prototype transdermal patch system of alfuzosin hydrochloride

The first-line therapy for moderate to severe benign prostatic hyperplasia is the oral therapy by alfuzosin hydrochloride. Unfortunately, the oral therapy of alfuzosin is associated with several route-specific systemic side-effects. The current study was aimed to develop a prototype transdermal patch system for alfuzosin using a hydrogel polymer and optimize the drug delivery through the skin for systemic therapy. The prospective of different chemical enhancers (polyethylene glycol (PEG 400), isopropyl myristate, propylene glycol, menthol and L-methionine; 5% w/v) and iontophoresis (0.3?mA/cm²) in the alfuzosin delivery across the full thickness rat skin was assessed in vitro. In vivo iontophoretic studies were carried out using selected patch system (PEG 400) for a period of 6?h in Sprague-Dawley rats. Passive permeation studies indicated that the incorporation of chemical agents have moderate effect (~?4- to 7-fold) on the alfuzosin skin permeability and reduced the lag time. Combined approach of iontophoresis with chemical enhancers significantly augmented the drug transport (~ 43- to 72-fold). In vivo pharmacokinetic parameters revealed that the iontophoresis (transdermal patch with PEG 400) significantly enhanced the C_max (~ 3-fold) and AUC_0-α (~ 4-fold), when compared to control. The current study concludes that the application of iontophoresis (0.3?mA/cm²) using the newly developed agaorse-based prototype patch with PEG 400 could be utilized for the successful delivery of alfuzosin by transdermal route.     

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.     

In Vivo and in Vitro Percutaneous Absorption and Skin Decontamination of Arsenic from Water and Soil

The objective was to determine the percutaneous absorption ofarsenic-73 as H₃A_sO₄ from water and soil. Soil (Yolo County65-California-57-8) was passed through 10-, 20-, and 48-meshsieves. Soil retained by 80 mesh was mixed with radioactivearsenic-73 at a low (trace) level of 0.0004 µg/cm² (microgramsarsenic per square centimeter skin surface area) and a higherdose of 0.6 µg/cm². Water solutions of arsenic-73 at alow (trace) level of 0.000024 µg/cm² and a higher doseof 2.1 µg/cm² were prepared for comparative analysis.In vivo in Rhesus monkey a total of 80.1 ± 6.7% (SD)intravenous arsenic-73 dose was recovered in urine over 7 days;the majority of the dose was excreted in the first day. Withtopical administration for 24 hr, absorption of the low dosefrom water was 6.4 ± 3.9% and 2.0 ± 1.2% fromthe high dose. In vitro percutaneous absorption of the low dosefrom water with human skin resulted in 24-hr receptor fluid(phosphate-buffered saline) accumulation of 0.93 ± 1.1%dose and skin concentration (after washing) of 0.98 ±0.96%. Combining receptor fluid accumulation and skin concentrationgave a combined amount of 1.9%, a value less than that in vivo(6.4%) in the Rhesus monkey. From soil, receptor fluid accumulationwas 0.43 ± 0.54% and skin concentration was 0.33 ±0.25%. Combining receptor fluid plus skin concentrations gavean absorption value of 0.8%, an amount less than that with invivo absorption (4.5%) in the Rhesus. These absorption valuesdid not match current EPA default assumptions. Washing withsoap and water readily removed residual skin surface arsenic,both in vitro and in vivo. The partition coefficient of arsenicin water to powdered human stratum corneum was 1.1 x 10⁴andfrom water to soil it was 2.5 x 10⁴. This relative similarityin arsenic binding to powdered human stratum corneum and soilmay indicate why arsenic absorption was similar from water andsoil. This powdered human stratum corneum partition coefficientmodel may provide a facile method for such predictions.     

Transdermal Delivery of Interferon Alpha-2B using Microporation and Iontophoresis in Hairless Rats

Purpose To demonstrate transdermal delivery of interferon alpha-2b (IFNα2b) in hairless rats through aqueous microchannels (micropores) created in the skin and enhanced by iontophoresis. Materials and Methods The Altea Therapeutics PassPort™ System was configured to form an array of micropores (2.0 cm²; 72 micropores/cm²) on the rat abdomen. The transdermal patch (Iomed TransQ1-GS-hydrogel) was saturated with an IFNα2b solution (600 μg/ml) and applied for 4 h. Delivery was evaluated with and without cathodic iontophoresis (0.1 mA/cm²). Intravenous delivery (0.4 μg/100 g body weight) was performed to support pharmacokinetic calculations. Results IFNα2b was not delivered through intact skin by itself (passive delivery) or during iontophoresis. However, passive delivery through micropores was achieved in vivo in rats. A dose of 397 ± 67 ng was delivered over 6 h, with steady state serum concentrations reaching a plateau at 1 h post-patch application. These levels dropped rapidly after patch removal, and returned to baseline within 2 h of patch removal. Iontophoresis-enhanced delivery through micropores resulted in a two-fold increase in the dose delivered (722 ± 169 ng) in the hairless rat. Conclusions In vivo delivery of IFNα2b was demonstrated through micropores created in the outer layer of the skin. Iontophoresis enhanced delivery through microporated skin in hairless rats.     

Evaluation of the Primary Skin Irritation and Allergic Contact Sensitization Potential of Transdermal Triprolidine

Evaluation of the Primary Skin Irritation and Allergic ContactSensitization Potential of Trans-dermal Triprolidine. ROBINSON,M. K., PARSELL, K. W., BRENEMAN, D. L., AND CRUZE, C. A. (1991).Fundam. Appl. Toxicol. 17, 103–119. A transdermal patchfor the OTC antihistamine, triprolidine (TP), might providebenefits in terms of increased efficacy and reduced sedativeside effects. However, concerns over potential irritant or allergiccontact sensitization (ACS) skin reactions necessitated thoroughskin toxicity testing before and during initial dinical developmentInitial effort was expended on development of a binary vehicledelivery system comprised of TP in 0.5% oleic acid (OA) in propyleneglycol (PG). Rabbit skin irritation and Buehler guinea pig skinsensitization testing indicated that this TP/OA/PG formula hadboth skin irritation and ACS potential. Both tests underestimated,to some degree, the skin toxicities observed in later clinicaltesting. In clinical tests, skin irritation was due mainly tothe OA–PG vehicle, but was enhanced in the presence ofhigh TP concentrations. Of 26 subjects enrolled in a risingdose clinical phar-macokinetics study, one subject exposed twiceto TP/OA/PG presented with delayed skin reactions suggestiveof ACS. Positive diagnostic patch test results for this subjectand four out of five other twice-exposed study subjects suggestedthat the TP/OA/PG formula had a very high ACS potential. Subsequentpredictive clinical patch testing was conducted with a bufferedaqueous TP formula which provided in vitro skin penetrationof the drug equivalent to the TP/OA/PG formula. These clinicalstudies demonstrated that TP itself had no significant irritationpotential but still induced ACS reactions in a high proportionof test subjects. The incidence of adverse skin reactions toTP was considered to be too high relative to the degree of improvedtherapeutic benefit of this delivery form. On this basis, alltechnology development effort was discontinued, © 1991by the Society of Toxicology     

In vitro and in vivo evaluation of a hydrogel-based prototype transdermal patch system of alfuzosin hydrochloride

The first-line therapy for moderate to severe benign prostatic hyperplasia is the oral therapy by alfuzosin hydrochloride. Unfortunately, the oral therapy of alfuzosin is associated with several route-specific systemic side-effects. The current study was aimed to develop a prototype transdermal patch system for alfuzosin using a hydrogel polymer and optimize the drug delivery through the skin for systemic therapy. The prospective of different chemical enhancers (polyethylene glycol (PEG 400), isopropyl myristate, propylene glycol, menthol and L-methionine; 5% w/v) and iontophoresis (0.3 mA/cm(2)) in the alfuzosin delivery across the full thickness rat skin was assessed in vitro. In vivo iontophoretic studies were carried out using selected patch system (PEG 400) for a period of 6 h in Sprague-Dawley rats. Passive permeation studies indicated that the incorporation of chemical agents have moderate effect (~4- to 7-fold) on the alfuzosin skin permeability and reduced the lag time. Combined approach of iontophoresis with chemical enhancers significantly augmented the drug transport (~ 43- to 72-fold). In vivo pharmacokinetic parameters revealed that the iontophoresis (transdermal patch with PEG 400) significantly enhanced the C(max) (~ 3-fold) and AUC(0-α) (~ 4-fold), when compared to control. The current study concludes that the application of iontophoresis (0.3 mA/cm(2)) using the newly developed agaorse-based prototype patch with PEG 400 could be utilized for the successful delivery of alfuzosin by transdermal route.     

The Predictive Accuracy of in Vitro Measurements for the Dermal Absorption of a Lipophilic Penetrant (Fluazifop-Butyl) through Rat and Human Skin

The predictive accuracy of in vitro measurements in estimatingdermal absorption has been evaluated in rat and human skin usingfluazifop-butyl (FB), a lipophilic model compound, at dosagerates of 2.5, 25, and 250 µg/cm² In vitro studies usedrat and human epidermal membranes mounted in static diffusioncells with radiolabeled FB and receptor fluids of 50% aqueousethanol (Aq Et), 6% polyethylene glycol 20 oleyl ether in saline(PEG), or tissue culture medium (TCM). In vivo rat studies withradiolabeled FB were carried out to parallel previously publishedhuman volunteer studies. For rat skin, in vitro measurementswith all types of receptor fluid provide an adequate prediction(generally within a factor of 3) of in vivo absorption. Absorptiondata for human epidermal membranes with a receptor fluid ofAq Et were adequately predictive of the in vivo absorption.In contrast, membranes with PEG or TCM significantly underestimatedthe in vivo absorption. The results support the conclusion thatin vitro studies are useful to predict in vivo dermal absorptionin rat and man, when appropriate receptor fluids are used.     

Pharmacokinetic and local tissue disposition of [14C]sodium diclofenac following iontophoresis and systemic administration in rabbits.

The systemic pharmacokinetics and local drug distribution of sodium diclofenac in skin and underlying tissues was studied. Iontophoresis facilitated local and systemic delivery of diclofenac sodium compared with passive diffusion. The maximum plasma concentration of sodium diclofenac was achieved within 1 h of iontophoresis, and the delivery was proportional to applied current density (371 +/- 141 and 132 +/- 62 microg/L at 0.5 and 0.2 mA/cm(2), respectively). The in vivo delivery efficiency for diclofenac in rabbit was 0.15 mg/mA.h. The concentrations of sodium diclofenac in the skin, subcutaneous tissue, and muscle beneath the drug application site (cathode) were significantly greater than plasma concentrations and concentrations of drug in similar tissues at the untreated sites. The results thus suggest that the cutaneous microvasculature is not always a perfect "sink" and that transdermal iontophoresis facilitated the direct penetration of diclofenac sodium to deeper tissues. No skin irritation was observed up to 0.5 mA/cm(2) current density and 7 mg/mL sodium diclofenac concentration.     

Effect of iontophoresis on in vitro transdermal absorption of almotriptan

The aim of the present work was to characterize the in vitro transdermal absorption of almotriptan through pig ear skin. The passive diffusion of almotriptan malate and its iontophoretic transport were investigated using current densities of 0.25 and 0.50 mA/cm². In vitro iontophoresis experiments were conducted on diffusion cells with an agar bridge without background electrolytes in the donor compartment. Although both current densities applied produced a statistically significant increment with respect to passive permeation of almotriptan (p < 0.01), that of 0.50 mA/cm² proved to be the best experimental condition for increasing the transport of almotriptan across the skin. Under these experimental conditions, the transdermal flux of the drug increased 411-fold with respect to passive diffusion, reaching 264 ± 24 μg/cm² h (mean ± SD). Based on these results, and taking into account the pharmacokinetics of almotriptan, therapeutic drug plasma levels for the management of migraine could be achieved via transdermal iontophoresis using a reasonably sized (around 7.2 cm²) patch.     

Repeated local administration of noradrenaline or saline inhibits thermal hyperalgesia in pain-sensitized human skin

AIMS: Noradrenaline increases thermal hyperalgesia in skin sensitized to heat by the topical application of capsaicin. The aim of this study was to determine whether desensitization to the hyperalgesic effects of noradrenaline would develop after repeated local administrations of noradrenaline in the skin of the forearm. METHODS: Noradrenaline and saline were administered to the forearm by iontophoresis (200 microA, 2 min, over a surface area of 3.1 cm(2)) two times per day for 4-10 days in 19 healthy subjects. The adequacy of the desensitization procedure was evaluated by measuring noradrenaline-induced vasoconstriction with laser Doppler fluxmetry. Thresholds and pain ratings to heat were then investigated at treated and control sites before and after the topical application of capsaicin, and after the iontophoresis of noradrenaline. RESULTS: At previously untreated sites blood flow was 49 +/- 14% (+/- 95% confidence intervals) lower than flow at reference sites after the iontophoresis of noradrenaline. Vascular signs of adrenergic desensitization developed after 4-5 days of repeated local administration of noradrenaline in the majority of subjects. In those whose vessels constricted after the acute administration of noradrenaline, the adrenergic response averaged 23 +/- 15% at the desensitized site compared with 61 +/- 9% at previously untreated sites (P < 0.001). However, similar signs developed after repeated iontophoreses of saline (adrenergic response 7 +/- 16% compared with 58 +/- 15% at previously untreated sites, P < 0.001). Both the noradrenaline and saline treatments inhibited thermal hyperalgesia after the topical application of capsaicin. Heat-pain thresholds averaged 43.2 +/- 2.5 degrees C and 43.0 +/- 2.3 degrees C at the noradrenaline and saline pretreated sites compared with 41.4 +/- 2.7 degrees C at the control site (P < 0.05 and P < 0.06, respectively). On a 0-10 scale, heat-pain ratings to a 7 s, 45 degrees C stimulus averaged 3.8 +/- 1.6 and 3.5 +/- 1.7 at the noradrenaline and saline pretreated sites compared with 5.3 +/- 1.6 at the control site (P < 0.05). After the iontophoresis of noradrenaline heat-pain ratings increased 1.6 +/- 1.4 at the site pretreated with saline (P < 0.05) compared with only 0.4 +/- 1.0 at the site pretreated with noradrenaline (not significant), consistent with local adrenergic desensitization. CONCLUSIONS: We conclude that repeated iontophoreses of noradrenaline or saline inhibit vasoconstriction to noradrenaline, and also inhibit increases in thermal hyperalgesia evoked by capsaicin. The release of endogenous stores of noradrenaline by iontophoretic currents might contribute to these effects.     

Glyphosate Skin Binding, Absorption, Residual Tissue Distribution, and Skin Decontamination

Glyphosate Skin Binding, Absorption, Residual Tissue Distribution,and Skin Decontamination. Wester, R. C., Melendres, J., Sarason,R., McMaster, J., and Maibach, H. I. (1991). Fundam. Appl. Toxicol.16, 725–732. Glyphosate is a broad-spectrum postemergencetranslocated herbicide. Its interactions with skin and potentialsystemic availability through percutaneous absorption was studiedby skin binding, skin absorption, residual tissue distribution,and skin decontamination. Glyphosate in a final formulation(Roundup) undiluted and diluted with water 1:20 and 1:32, wouldnot partition into powdered human stratum corneum (<1%).In vitro percutaneous absorption through human skin into humanplasma as receptor fluid was no more than 2% over a concentrationrange of 0.5–154 µg/cm² and a topical volume rangeof 0.014–0.14 ml/cm². Disposition of glyphosate followingiv administration of 93 and 9 µg doses to rhesus monkeyswas mainly through urine excretion, 95 ± 8 and 99 ±4% in 7 days, respectively. Percutaneous absorption in vivoin rhesus monkey was 0.8 ± 0.6% for the low dose (25µg/cm²) and 2.2 ± 0.8% for the high dose (270 µg/cm²).No residual ¹⁴C was found in organs of the monkeys euthanized7 days after the topical application. Washing the skin applicationsite with soap and water removed 90 ± 4% of applied dose,and washing with water only removed 84 ± 3% of applieddose. Both soap and water and water only were equal in abilityto remove glyphosate from skin over a 24 hr skin applicationperiod. About 50% of the initially applied dose could be recoveredafter 24 hr. Glyphosate is very soluble in water and insolublein most organics (octanol/water log P = –1.70) and thereforenot compatible with the lipid-laden stratum corneum. This isconsistent with the low skin binding and skin absorption andalso consistent with the efficient removal from skin with soapand water or water-only wash.     

Percutaneous Absorption and Excretion of Alacholr in Rhesus Monkeys

Percutaneous Absorption and Excretion of Alachlor in RhesusMonkeys. KRONENBERG, J. M., FUHREMANN, T. W., AND JOHNSON, D.E., (1988) Fundam Appl Toxicol 10, 664–671. The percutaneousabsorption and excretion profile of alachlor were evaluatedin rhesus monkeys. A preliminary study demonstrated that anaverage of 86.7 and 9.7% of the administered dose was recoveredin the urine and feces, respectively, following intravenousadministration of radiolabeled alachlor to rhesus monkeys. Insubsequent studies, diluted and undiluted emulsifiable concentrate(EC) and microencapsulated (ME) formulations of radiolabeledalachlor were applied to a 40-cm² shaved abdominal area andallowed to remain on the skin for 12 hr. The radioactivity excretionprofiles in all animals were comparable. In all cases, approximately88% of the absorbed dose was eliminated via the urine, primarilywithin the first 48 hr. Comparison of the amount of radiolabelrecovered in the topical studies with that recovered followingintravenous administration indicated that an average of 8.5and 3.7% of the alachlor in the topically applied EC and MEformulations, respectively, was absorbed.     

静脉注射瑞芬太尼对兔定量药物脑电图β_2和θ频段功率百分比的影响

目的探讨瑞芬太尼对兔定量药物脑电图(QPEEG)β2和θ频段功率百分比的影响,及该影响与阿片受体的关系。方法健康成年兔按照体质量随机分组,每组6只,分别iv给予生理盐水1 ml·kg-1,瑞芬太尼5,10和15μg·kg-1,纳洛酮200μg·kg-1以及纳洛酮200μg·kg-1+瑞芬太尼15μg·kg-1(间隔5 min)。应用数字脑电地形图仪分别记录给药前30 s及给药后30 s,1,2,3,5,10,15,20和25 min兔左、右脑额、顶、枕和颞8个脑区QPEEG,并定量β2和θ频段功率百分比。结果与给药前相比,生理盐水1 ml·kg-1组、瑞芬太尼5μg·kg-1组和纳洛酮200μg·kg-1组各脑区β2频段功率百分比均无明显变化;瑞芬太尼10和15μg·kg-1组各脑区在给药后30 s～5 min期间β2频段功率百分比增加(P<0.05);生理盐水1 ml·kg-1,瑞芬太尼5和10μg·kg-1及纳洛酮200μg·kg-1对各脑区θ频段功率百分比均无明显影响,瑞芬太尼15μg·kg-1组各脑区在给药后30 s～5 min期间θ频段功率百分比减小(P<0.05);β2频段功率百分比的变化与瑞芬太尼剂量呈正相关(P<0.01);θ频段功率百分比的变化与瑞芬太尼剂量呈负相关(P<0.01)。与瑞芬太尼15μg·kg-1组相比,纳洛酮200μg·kg-1+瑞芬太尼15μg·kg-1组各脑区β2频段功率百分比降低(P<0.05),θ频段功率百分比增高(P<0.05),与给瑞芬太尼前无明显差异。结论瑞芬太尼以剂量依赖方式增加兔QPEEGβ2频段功率百分比,同时也以剂量依赖方式减少θ频段功率百分比,纳洛酮可拮抗瑞芬太尼的这种脑电图效应,表明这一作用由阿片受体介导,提示β2和θ频段功率百分比可能成为瑞芬太尼镇痛程度的监测指标。     

Comparative dermatotoxicology: I. Direct comparison of rabbit and human primary skin irritation responses to isopropylmyristate

The primary skin irritation properties of isopropylmyristate (IPM) have been determined for rabbit and human skin. In rabbit studies, an occluded patch procedure was used in which irritation due to a vehicle was eliminated. Known amounts of IPM were applied to patches with ethanol as a vehicle. A radiotracer study showed the ethanol could be evaporated to a nonirritating level prior to use of the patch. This procedure was used with an experimental design that improved the efficiency of the irritation test by allowing removal of animal-to-animal variability and permitting four different treatments on each animal at one time. Four consecutive 23-hr occluded exposures of rabbit skin to 6.3 mg IPM/cm² of patch produced moderate erythema according to the Draize scale while four exposures to 23 or 85 mg IPM/cm² of patch produced moderate to severe erythema with very slight edema. A single exposure at doses ranging from 1.7 to 85 mg IPM/cm² of patch produced responses ranging from no erythema to well-defined erythema. The responses to a single exposure were less with 1 or 4 hr of occlusion than with 23 hr. A statistical analysis showed substantial variation in irritation scores from skin site-to-skin site but no tendency for one site on the rabbits' backs to have systematically higher scores than another. Human studies were conducted with experimental conditions the same as for the rabbit. Four consecutive 23-hr occluded exposures of human back skin to 85 mg IPM/cm² of patch produced only very slight erythema with no edema. The results of these studies support the use of IPM as a model species-variable skin irritant to study the biological basis for the variability of skin irritation among species.     

可溶性鸡Ⅱ型胶原对大鼠胶原性关节炎的免疫治疗作用

目的　考察可溶性鸡Ⅱ型胶原 (SCCⅡ )对大鼠胶原性关节炎 (CIA)的免疫治疗作用及机制。方法　检测CIA大鼠血清抗Ⅱ型胶原 (CⅡ )抗体、腹腔巨噬细胞 (PMΦ)与滑膜细胞产生白介素 1(IL 1)和肿瘤坏死因子α(TNFα)和SCCⅡ /刀豆球蛋白A(ConA)诱导 5个部位淋巴细胞的增殖反应 ,同时测量继发炎症反应和免疫器官系数。结果　ig 0 .0 3,0 .3和 3.0mg·kg- 1·d- 1SCCⅡ (d 14～ 2 2 ) ,明显减轻患鼠继发炎症 ,抑制针对SCCⅡ的皮肤迟发型超敏反应和PMΦ,滑膜细胞超常分泌IL 1和TNFα ,促进体重和免疫器官系数恢复 ,提升低下的淋巴细胞ConA反应 ,但不能降低血清抗CⅡ抗体水平 ,5个部位的淋巴细胞对SCCⅡ体外刺激也几无反应性。结论　SCCⅡ通过T细胞免疫耐受途径对大鼠CIA产生治疗作用。     

小鼠精母细胞钙通道特性及硝苯地平的作用

目的　为了建立一个合理、客观评价药物或毒物对生殖系统影响的细胞模型 ,研究了机械分离、未经酶消化的小鼠精母细胞Ca2 + 通道特性及硝苯地平对其的作用。方法　采用全细胞膜片钳技术。结果阻断K+ 电流后 ,当钳制电位 -90mV、指令电压 -80～ +1 0mV、步阶电压 1 0mV时 ,记录到Ca2 +电流 ,二价无机阳离子对Ca2 + 电流的抑制作用Ni2 +>Cd2 + ,而L型Ca2 + 通道激动剂BayK8644对电流无任何影响。分析小鼠精母细胞上记录的Ca2 + 电流为T型Ca2 + 通道开放产生。L型Ca2 + 通道阻断剂硝苯地平对精母细胞Ca2 + 电流有明显的抑制作用 ,半数最大抑制浓度为 0 .3 9μmol·L-1,而且细胞外液冲洗恢复缓慢 ,这支持了二氢吡啶类药物可用于男性避孕。结论　机械分离、未经酶消化的小鼠精母细胞模型适合进行药理学和毒理学研究     

New Surface Covering for Feminine Hygiene Pads: Dermatological Testing

ABSTRACT

The skin compatibility of a new surface covering for feminine hygiene pads was assessed by 1) skin irritation patch tests, 2) the Human Repeat Insult Patch Test, and 3) a test protocol for assessing mechanical irritation that uses repeated application to the popliteal fossa (“behind-the-knee” test). The pad covering is a fabric-like apertured film with a soft and supple tactile impression. Testing was designed to assess the effects of topical contact as well as friction. All studies showed the new material to be as mild as other commercially available materials used on the surface of feminine hygiene pads. Induction of delayed contact hypersensitivity was not found. The test methods used can be applied to the safety assessment of other products that involve topical skin contact and frictional effects.