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Manipulating systemic and mucosal immune responses with skin-deliverable adjuvants.

Most medically important bacterial and viral pathogens gain entry into the body either via the skin or a mucosal surface. Vaccination provides a viable and cost-effective strategy for the prevention of such diseases and it has always been a principal aim with vaccinologists, to be able to promote simultaneously, protective immune responses both systemically and at mucosal surfaces. The paradigm that mucosal immunity is best stimulated by exposure to antigen via a mucosal route simply because inductive sites such as Peyer's patches and bronchial associated lymphoid tissues are located in the mucosal epithelium, has promoted a plethora of immunizing strategies aimed at delivering both antigen and adjuvant to mucosal surfaces. We have developed a novel adjuvant system capable of intradermal delivery of antigens complexed in an ISCOSOME delivery vehicle. This adjuvant, referred to as a skin and mucosal adjuvant or SAMA4, was efficacious in eliciting both systemic and mucosal IgG and IgA antibodies in sheep, pigs and mice. SAMA4 does not induce granulomatous lesions at the site of vaccine delivery and can be used to deliver adjuvanted antigens by other routes including intranasal, oral and intravaginal. Using ovalbumin as a test antigen, intradermally delivered ovalbumin-SAMA4 complexes was found to be very effective in promoting a cytotoxic T cell response. Attempts to dissect the mode of action of SAMA4 by flow cytometric analysis of lymphocyte populations from the spleen, lung, liver and thymus revealed an effect of route of vaccine delivery upon the composition of specific lymphocyte subsets in these various organ compartments. From this, it can be inferred that SAMA4 induced a route-dependent re-mobilization and alteration in lymphocyte trafficking patterns. Other mucosal adjuvants such as cholera toxin B and microspheres, when injected intradermally, tended to promote primarily, an IgG and not an IgA response against hte carrier antigen.

Animals↗

Blockade of the flare response to intradermal 5-hydroxytryptamine in man by MDL 72.222, a selective antagonist at neuronal 5-hydroxytryptamine receptors.

MDL 72.222 is a potent and selective antagonist of excitatory neuronal 5-hydroxytryptamine (5-HT) receptors which has been shown to provide symptomatic benefit in migraine. In the present study, the effects of MDL 72.222 on the flare response to intradermal injection of 5-HT (10(-5), 4 X 10(-5) and 1.6 X 10(-4) mol/l) have been examined in six healthy male volunteers using a double-blind, placebo-controlled, randomized, crossover design. The study consisted of two sessions separated by at least 5 days. Comparison of within and between day responses to 5-HT indicated good reproducibility. Significant attenuation of the flare response to 5-HT, 10(-5) and 4 X 10(-5) mol/l was observed following a slow (4 min) i.v. injection of MDL 72.222, 20 mg. No significant change was observed for the 1.6 X 10(-4) mol/l dose. The investigator was able to guess with a high degree of accuracy the sequence of MDL 72.222 and placebo (100% correct) and the order of 5-HT dose administration (70% correct), providing further evidence of the reproducibility and sensitivity of the method. MDL 72.222 was well tolerated. Thus, a dose of MDL 72.222 previously shown to provide symptomatic relief in migraine attenuates the flare response to intradermal 5-HT in the human forearm. The observation strengthens the view that the beneficial effects of MDL 72.222 in migraine result from blockade of the sensory neuronal stimulant effects of 5-HT and implies a role for 5-HT in the pain production of the acute attack.

Adult↗

Effects of topically applied clobetasol-17-propionate on histamine release in human skin.

The effects of topical glucocorticoid treatment on histamine responses and histamine release induced by the histamine liberating agent compound 48/80 were studied in 17 healthy volunteers. The potent glucocorticoid ointment clobetasol-17-propionate was applied on one upper arm of each individual 14, 4 and 2 hours before testing. The other arm was treated in the same way with the corresponding vehicle. Solutions of histamine and compound 48/80 were injected intradermally in both arms. The size of the flare reaction and the duration of the itch response were recorded. It was found that the flare reactions evoked by histamine were slightly (p less than 0.05) reduced on the steroid-pretreated arm whereas the responses to compound 48/80 were much more suppressed (p less than 0.01). Glucocorticoid treatment did not influence the itch responses to histamine while the itch duration following injection of compound 48/80 was significantly reduced in steroid-treated skin compared to control skin. Our results indicate that topical glucocorticoid treatment can suppress histamine release from dermal mast cells in man.

Adult↗

IMMUNOLOGICAL TOLERANCE INDUCED IN ANIMALS PREVIOUSLY SENSITIZED TO SIMPLE CHEMICAL COMPOUNDS.

Adult guinea pigs develop a delayed hypersensitivity to intradermally injected neoarsphenamine. If the animals are treated intravenously with high doses of this compound before sensitization, a specific and permanent immunological tolerance develops. Permanent tolerance is also obtained in previously sensitized animals when an intravenous injection of neoarsphenamine isfollowed 6 hours later by an intradermal one. When, however, the interval between the two injections is extended to 7 or 14 days, no tolerance is observed.

Animals↗

The effect of delipidated deglycolipidated (DDMV) and heat-killed Mycobacterium vaccae in asthma.

Experimental and epidemiological evidence supports the hypothesis that exposure to mycobacteria has the potential to suppress the development of asthma and/or atopy and there are reports in the Chinese medical literature of repeated vaccination with inactivated BCG being effective in the management of asthma. Forty-three patients with stable moderately severe asthma who were skin prick test positive to house dust mite were randomized to receive two intradermal injections of either phosphate-buffered saline (placebo), heat-killed Mycobacterium vaccae (0.5 mg), or delipidated deglycolipidated Mycobacterium vaccae (DDMV) (0.05 mg). Markers of asthma severity were measured for 3 mo and blood eosinophil, IgE levels, and the T cell proliferative and cytokine responses were monitored. There were no significant differences between either treatment group and the placebo group for any of the outcome variables. There was also no difference between the treatment groups and placebo for eosinophil, IgE levels, or the T cell proliferative and cytokine response. The results indicate no effect of low dose intradermal DDMV or M. vaccae on asthma severity in patients with established asthma.

Adult↗

A delayed type hypersensitivity (DTH) skin reaction to hepatitis B surface antigen (HBsAg) and intradermal hepatitis B vaccination.

The significance of a delayed type hypersensitivity skin reaction to hepatitis B surface antigen (HBsAg) (HBs-DTH) in type B viral hepatitis (VHB) and in intradermal hepatitis B (HB) vaccination is reviewed. HBs-DTH could be developed by the intradermal injection of HB vaccine in anti-HBs positive people and also in persons immunized with HB vaccine. Thus, HBs-DTH could serve as a useful marker for the acquisition of an active Th1 type immunoreactivity to HBsAg. HBs-DTH was absent in patients with chronic VHB. In contrast, HBs-DTH developed early in the convalescent phase of the acute VHB, whereas the production of anti-HBs was significantly delayed, thus suggesting that HBs-DTH may be involved in the recovery mechanisms of acute VHB. Intradermal HB vaccination is useful not only in lowering the cost, but also in the rapid development of anti-HBs, reversing non-responsiveness, improving postexposure prophylaxis and in immunizing immunosuppressed people. A similar vaccination strategy should prove to be useful in prevention and control of not only other infectious diseases but also malignant neoplasms.

Hepatitis B Surface Antigens↗

Intraoperative lymphatic mapping for vulvar cancer.

OBJECTIVE: To determine the feasibility of intraoperative lymphatic mapping in patients with vulvar cancer. METHODS: Isosulfan blue was injected intradermally at the junction of tumor and normal skin in nine patients. We then attempted to identify the dye in the superficial lymphatic channels and in a superficial groin lymph node. RESULTS: The sentinel node was identified in seven of 12 groins in seven of the nine subjects studied. Six of the successful cases had unilateral lesions. The cases in which a sentinel node was not identified were both patients with midline lesions, including one whose scar was injected following a prior wide local excision of a perineal tumor and one who appeared to have direct drainage to the deep pelvic nodes. There were no technique-related complications. In no case was there a positive non-sentinel node in the presence of a negative sentinel node. CONCLUSION: Intraoperative lymphatic mapping is technically feasible in patients with vulvar cancer, particularly those with unilateral disease. Further experience is needed to evaluate the reliability of the technique in identification of groin node metastases.

Carcinoma, Squamous Cell↗

Botulinum toxin A for axillary hyperhidrosis (excessive sweating).

BACKGROUND: Treatment of primary focal hyperhidrosis is often unsatisfactory. Botulinum toxin A can stop excessive sweating by blocking the release of acetylcholine, which mediates sympathetic neurotransmission in the sweat glands. METHODS: We conducted a multicenter trial of botulinum toxin A in 145 patients with axillary hyperhidrosis. The patients had rates of sweat production greater than 50 mg per minute and had had primary axillary hyperhidrosis that was unresponsive to topical therapy with aluminum chloride for more than one year. In each patient, botulinum toxin A (200 U) was injected into one axilla, and placebo was injected into the other in a randomized, double-blind manner. (The units of the botulinum toxin A preparation used in this study are not identical to those of other preparations.) Two weeks later, after the treatments were revealed, the axilla that had received placebo was injected with 100 U of botulinum toxin A. Changes in the rates of sweat production were measured by gravimetry. RESULTS: At base line, the mean (+/-SD) rate of sweat production was 192+/-136 mg per minute. Two weeks after the first injections the mean rate of sweat production in the axilla that received botulinum toxin A was 24+/-27 mg per minute, as compared with 144+/-113 mg per minute in the axilla that received placebo (P< 0.001). Injection of 100 U into the axilla that had been treated with placebo reduced the mean rate of sweat production in that axilla to 32+/-39 mg per minute (P<0.001). Twenty-four weeks after the injection of 100 U, the rates of sweat production (in the 136 patients in whom the rates were measured at that time) were still lower than base-line values, at 67+/-66 mg per minute in the axilla that received 200 U and 65+/-64 mg per minute in the axilla that received placebo and 100 U of the toxin. Treatment was well tolerated; 98 percent of the patients said they would recommend this therapy to others. CONCLUSIONS: Intradermal injection of botulinum toxin A is an effective and safe therapy for severe axillary hyperhidrosis.

Adult↗

Dermal infection with vaccinia virus reveals roles for virus proteins not seen using other inoculation routes.

Previously, we developed a model for testing the virulence and immunogenicity of vaccinia virus (VV) mutants based on the intradermal injection of BALB/c mouse ear pinnae. The model is characterized by a local infection in the inoculated skin without signs of systemic illness, mimicking dermal vaccination with VV. Here a further characterization of this model is presented, including the responses of mice to infectious virus doses as low as 10 p.f.u., a quantification of the infiltrate at the site of infection and use of different virus and mouse strains. The model was then used to compare the pathogenesis of six mutants of VV strain Western Reserve (WR) lacking genes A36R, A40R, A44L, B12R, B13R or B15R with that of appropriate control viruses. All of these genes except B12R and B15R influence the outcome of dermal infection with WR and for A40R and B13R this is the first role that has been reported after infection of mammals. A comparison of new and published results from intradermal and intranasal models is presented, showing that out of 16 gene deletion or insertion mutants of VV, half have phenotypes distinct from controls in only one of these models. Thus, the intranasal and intradermal models are complementary tools for dissecting the genetic basis of VV virulence.

Age Factors↗

Secondary hyperalgesia persists in capsaicin desensitized skin.

Several lines of evidence suggest that secondary hyperalgesia to punctate mechanical stimuli arises from central sensitization to the input from primary afferent nociceptors. Conventional C-fiber nociceptors respond to heat stimuli and yet heat hyperalgesia is absent in the region of secondary hyperalgesia. This evidence suggests that the central sensitization to nociceptor input does not involve heat sensitive nociceptors. To test this hypothesis, we investigated whether desensitization of heat sensitive nociceptors by topical application of capsaicin led to an alteration in the secondary hyperalgesia. Two 2x2 cm areas on the volar forearm, separated by 1 cm, were treated in 10 healthy volunteers. One of the areas was desensitized by treatment with 10% topical capsaicin (6 h/day for 2 days). The other site served as vehicle control. Hyperalgesia was produced 2 days later by an intradermal injection of capsaicin (50 microg, 10 microl) at a point midway between the two treatment areas. Secondary hyperalgesia to noxious mechanical stimuli was investigated by using a blade probe (32 and 64 g) attached to a computer-controlled mechanical stimulator. In the area of topical capsaicin treatment, there was a marked increase in heat pain threshold and decrease in heat pain ratings indicating a pronounced desensitization of heat sensitive nociceptors. However, touch threshold and pain to pinching stimuli were not significantly altered. The intradermal capsaicin injection led to the development of a similar degree of secondary hyperalgesia at both the vehicle and capsaicin treatment areas. These results indicate that capsaicin insensitive nociceptive afferents play a dominant role not only in normal mechanical pain but also in secondary hyperalgesia to noxious mechanical stimuli.

Administration, Topical↗

Tattoo removal by overtattooing with tannic acid.

Removal of tattoos was studied in the guinea pig. Professional tattoos were made, and two different solutions of tannic acid were injected intradermally into the tattoos four times. The macroscopic end result was formation of a slight fibrosis with little visible pigment. Histologic examination after treatment showed a moderate fibrosis with little visible pigment situated deeper in the dermis than in the untreated tattoo.

Animals↗

Assessment of respiratory hypersensitivity in guinea-pigs sensitized to diphenylmethane-4,4'-diisocyanate (MDI) and challenged with MDI, acetylcholine or MDI-albumin conjugate.

Guinea-pigs were sensitized to monomeric diphenylmethane-4,4'-diisocyanate (MDI) by two intradermal injections (1-10% MDI, injection volumes of 50-100 microliters/day, on days 0, 2 and 4) or by a single brief high-concentration inhalation exposure (135 or 360 mg/m3, 15 min). Starting with day 21 following sensitization the animals were subjected to inhalation-challenge exposures (30 min) with non-irritating and irritating concentrations of the hapten (MDI). MDI-challenge concentrations ranged from 3.4 +/- 0.9 to 60 +/- 14.3 mg/m3 air. In some groups guinea-pigs were also challenged with acetylcholine (ACh) aerosol or the MDI-guinea pig serum albumin (GPSA) conjugate. Experimental findings indicated that from intradermally sensitized animals an immediate onset respiratory hypersensitivity response could only be elicited with concentrations exceeding the irritant threshold concentration for MDI, i.e. with concentrations greater than approximately 20 mg/m3 air. Guinea-pigs challenged with the MDI-GPSA conjugate (35.3 +/- 2.8 mg/m3 air) also experienced a weak immediate-type respiratory hypersensitivity response. An increased non-specific airway hyper-responsiveness following ACh-challenge was only observed from animals challenged with approximately 60 mg MDI/m3 air. The histopathological evaluation of lungs and lung-associated lymph nodes revealed an association of the increase in eosinophilic granulocytes and concentration of MDI used for challenge exposures. It appeared, in most instances, that this influx was more pronounced in animals sensitized with MDI as compared with concurrent controls challenged with the same MDI concentration. Guinea-pigs sensitized by a single 15-min inhalation exposure to either 135 or 360 mg MDI/m3 air were challenged sequentially with 12 +/- 2.1 mg MDI/m3 air, ACh and MDI-GPSA conjugate. Following the inhalation-induction, an airway hyper-responsiveness was elicited both after challenge with MDI and with the MDI-GPSA conjugate. The influx of eosinophilic granulocytes was more pronounced from animals sensitized by inhalation when compared with guinea-pigs sensitized intradermally and challenged with the same concentration of MDI. Thus, experimental findings suggest that elicitation of respiratory hypersensitivity is concentration-dependent and that challenge concentrations should slightly exceed the threshold concentration for irritation (approximately 20 mg/m3). Sensitization by inhalation increased the susceptibility to irritant stimuli and thus confounds the selection of the most appropriate concentration for challenge. However, the combined assessment of specific pathologic features such as airway eosinophilia and the evaluation of several breathing parameters during hapten- and ACh-challenge make it easier to distinguish effects caused by irritation and respiratory hypersensitivity.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗

Localized intradermal microinjection of tranexamic acid for treatment of melasma in Asian patients: a preliminary clinical trial.

BACKGROUND: Melasma is a common cosmetic problem among Asians. While various treatments are currently being used, there is no entirely satisfactory treatment. It was recently reported that the topical plasmin inhibitor is an effective treatment for ultraviolet-induced hyperpigmentation. OBJECTIVE: Because there are no studies assessing the efficacy and safety of localized microinjection of tranexamic acid (TA) for the treatment of melasma, we conducted a pilot study to evaluate the efficacy and side effects of this potentially new method for the treatment of melasma in Korean women. METHODS: A total of 100 women with melasma, after written consent, were enrolled for a prospective open pilot study of 12 weeks. After applying topical anesthesia, 0.05 mL TA (4 mg/mL) was injected intradermally into the melasma lesion at 1 cm intervals by using a 0.5 mL insulin syringe with a 30-gauge needle. This was repeated weekly for 12 weeks. A clinical investigator evaluated the results by using the Melasma Area and Severity Index (MASI) at baseline and at 4, 8, and 12 weeks. The patient satisfaction questionnaire was documented at 12 weeks. Safety evaluations were performed at each follow-up visit. RESULTS: Eighty-five patients completed the trial. A significant decrease in the MASI from baseline to 8 and 12 weeks was observed (13.22+/-3.02 vs 9.02+/-2.62 at week 8 and vs. 7.57+/-2.54 at week 12; p<.05 for both). The patients' self-assessment of melasma improvement was as follows: 8 of 85 patients (9.4%) rated as good (51-75% lightening), 65 patients (76.5%) as fair (26-50% lightening), and 12 patients (14.1%) as poor (0-25% lightening). Side effects were minimal and all the patients tolerated the treatment well. CONCLUSION: Based on these results, we suggest that the intralesional localized microinjection of TA acid can be used as a potentially new, effective, and safe therapeutic modality for the treatment of melasma.

Adult↗

Intradermal sufentanil does not improve lidocaine-induced local anesthesia.

PURPOSE: Peripheral opioid receptors may result in antinociceptive effects when occupied by opioids. This study examined intradermally injected sufentanil (S), a highly lipid soluble opioid, administered with and without lidocaine (L), in a thermal pain model. METHODS: Nine volunteers were instructed on the method of magnitude estimation of pain before undergoing baseline testing with seven seconds thermal stimuli between 44 and 52 degrees C, delivered by a contact thermal stimulator at five cutaneous forearm sites. Then, four sites randomly received injections of equal volumes (0.1 mL) of either normal saline (NS), lidocaine 0.5% (L), sufentanil 0.75 microg (S), lidocaine 0.5% plus sufentanil 0.75 microg (L+S), and one site was not injected and served as reference (REF). Testing was repeated at six, 30, 60, 90, 120, and 150 min following injection. The pain elicited by each stimulus was normalized to the subject's response to the 50 degrees C stimulus at the REF site. RESULTS: Baseline testing showed small (P = ns) differences in pain scores. At six minutes, the lidocaine sites (L, L+S) had pain scores that were mean 83% (range 78-88%) lower than the other sites (P < 0.05), but there was no difference between the L and L+S sites or between the S and NS or REF sites. At 30 and 60 min these pain scores were mean 38% (29-44%) and 20% (8-30%) less than at the REF, NS, and S sites (P = ns). At 90 min and later times, the pain scores had returned to baseline. CONCLUSIONS: These results suggest that intradermal sufentanil alone has no analgesic effect. Further, in combination with lidocaine, sufentanil does neither potentiate nor prolong the analgesic effect of lidocaine.

Adult↗

The interaction between Treponema pallidum and human polymorphonuclear leukocytes.

The interaction between polymorphonuclear leukocytes (PMNLs) and Treponema pallidum was studied. Intradermal injection of greater than or equal to 10(6) T. pallidum into rabbits caused a rapid accumulation of PMNLs. Human serum released chemotaxigenic factor (C5a) during incubation in vitro with T. pallidum. Incubation of T. pallidum with human PMNLs in vitro (ratio, 100:1) stimulated chemiluminescence. These responses were dependent upon the presence of both antibody and complement and were greatest when serum from a patient with late secondary syphilis was used as a chemotaxigenic source or for opsonization. Electron microscopic studies documented the rapid uptake of T. pallidum into membrane-bound vacuoles in the human PMNLs in vitro after incubation for as little as 5 min, with leukocyte degranulation and loss of treponemal integrity observed after 4 hr. T. pallidum were found within PMNLs 3 hr after intradermal inoculation of rabbits. These data show that PMNLs are attracted to, and appear to ingest, T. pallidum, but they fail to explain why inoculation of these organisms is not followed by eradication.

Animals↗

Nitric oxide-dependent release of vasodilator quantities of calcitonin gene-related peptide from capsaicin-sensitive nerves in rabbit skin.

1. Calcitonin gene-related peptide (CGRP) is a potent and long lasting vasodilator in the cutaneous microvasculature of many species including the rabbit. In this study we have investigated the role of nitric oxide in the release of endogenous CGRP, in response to capsaicin, in rabbit skin. 2. Cutaneous blood flow was measured in response to intradermally-injected agents by a multiple site 133Xenon clearance technique. 3. The increased blood flow induced by capsaicin (100 nmol/site) and CGRP (3 pmol/site) was totally inhibited by the CGRP antagonist CGRP(8-37) (1 nmol/site), whilst the increased blood flow induced by sodium nitroprusside (0.3, 1 and 3 nmol/site) was unaffected by CGRP(8-37). 4. The nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 30 nmol/site) had no effect on the vasodilator response induced by CGRP, but significantly inhibited capsaicin-induced blood flow. The inhibitory effect of L-NAME on capsaicin-induced blood flow was reversed by intradermal L-arginine (300 nmol/site), whilst the inactive enantiomer D-NAME (30 nmol/site) and the alpha-adrenoceptor agonist phenylephrine (10 pmol/site), at a dose which had a similar effect to L-NAME on basal blood flow, had no effect on capsaicin-induced blood flow. 5. These results suggest that CGRP is the important vasodilator which is released from capsaicin-sensitive sensory nerves in rabbit skin and that the release of CGRP, but not its mechanism of vasodilator action, is nitric oxide-dependent in the rabbit cutaneous microvasculature.

Animals↗

Studies of human C5a as a mediator of inflammation in normal human skin.

C5a is an 11,000-D fragment of the fifth component of complement (C5) with potent anaphylatoxic and leukocyte chemotactic activities. C5a is believed to play an important role in the pathophysiology of certain skin disorders and systemic diseases with cutaneous manifestations. However, there is very little known about the in vivo reactivity of C5a in man. In this study we examined the effects of intradermal injections of human C5a in 17 normal volunteers. C5a was prepared by interacting highly purified human C5 with zymosan bound alternative pathway C5 convertase under conditions resulting in consumption of approximately 90% of the C5 substrate. C5a produced in this manner was chemotactic for human neutrophils and monocytes (0.5 X 10(-7) to 10(-9) M) and caused neutrophil aggregation and myeloperoxidase release (concentrations greater than or equal to 10(-10) M) in vitro. In vivo, C5a produced immediate wheal and flare reactions in all volunteers, and was active in doses as low as 1 ng (10(-13) mol). Intradermal testing with 20 ng of C5a in eight volunteers produced a maximal mean wheal of 11.75 mm (+/- 0.80 mm SEM) 20 min after anaphylatoxin injection, and a maximal mean erythema of 62.50 mm (+/- 3.27 mm SEM) 10 min after C5a administration. Reactions at C5a test sites were dose-related, associated with marked pruritus in some subjects, resolved without lesion formation, and were not associated with late phase reactions. In vivo testing revealed that human C5a was a more potent mediator of wheal and flare reactions than histamine, 48/80, human C3a, or morphine sulfate. Skin biopsies from eight volunteers 20 min after intradermal injection of 20 ng of C5a revealed a neutrophil-predominant perivascular infiltrate, endothelial cell edema, and sites of leukocytoclasis. Mast cell degranulation was observed on both light and electron microscopy of biopsies from C5a test sites. Although erythema at C5a injection sites was reduced by pretreating volunteers with hydroxyzine, whealing reactions and cellular infiltrates in biopsies were unaffected by this H1-antihistamine. Moderate doses of systemic corticosteroids did not alter clinical or histologic reactions at C5a injection sites in two volunteers. This study, using doses within the potential physiologic range of the anaphylatoxin, provides a comprehensive assessment of the effect of human C5a on normal human skin.

Adult↗

Characterization of cutaneous phototoxicity induced by topical alpha-terthienyl and ultraviolet A radiation.

Alpha-terthienyl (alpha-T), a phototoxic thiophene compound isolated from marigolds (Tagetes species), affects cell membranes and does not appear to induce cytogenetic damage. This study was undertaken to investigate topical delivery of alpha-T and characterize its cutaneous phototoxicity in combination with long-wave UV radiation (UVA) in comparison with locally (intradermal) administered alpha-T. Percutaneous penetration (PC) of 0.1% and 1% alpha-T in a 3% Azone gel vehicle was studied in guinea pig skin in vitro and quantitated by UV fluorescence microscopy. Dose-dependent PC of epidermis, adnexae, and superficial dermis was demonstrated in vitro. Alpha-terthienyl (0.1% and 1%) in this vehicle was applied topically in vivo and irradiated with 30 J/cm2 UVA at intervals of 10 min-24 h. Maximum sensitization was achieved with irradiation 1 h following drug application. The clinical response was dose-dependent consisting of erythema, edema, crusting, erosion, and inhibition of hair growth and was observed 72 h to 7 days postirradiation. A comparable dose-dependent phototoxic response was observed when 5-500 micrograms alpha-T were injected intradermally and irradiated with UVA. These results indicated that low-dose topical alpha-T in a nonirritating vehicle can rapidly produce cutaneous photosensitization. Topical alpha-T/UVA may provide a selective and safer alternative approach for the photochemotherapy of psoriasis and other cutaneous diseases.

Administration, Oral↗