Lack of efficacy of topical capsaicin in serotonin-induced itch

Capsaicin (CAP) has been demonstrated to be an effective topical inhibitor of cutaneous vasodilatation, pain and pruritus induced by a variety of chemical and physical stimuli. In a previous study, we showed a significantly inhibitory effect of topical CAP treatment on histamine-induced itch and cutaneous vascular reactions in healthy subjects compared to atopic eczema patients. As serotonin is proposed to play a pathophysiological role in some types of pruritus (e.g. uremic and hepatic pruritus) and CAP has been described to be successful in hemodialysis-related pruritus, we investigated the antipruritic effect of topical CAP on serotonin-induced reactions in 10 healthy volunteers in comparison to untreated skin (UPS) and placebo substance (vehicle)-treated skin (VS). On the first day, serotonin iontophoresis was performed in untreated skin. One week later, the treatments started, using either CAP 0.05% liniment or a placebo liniment (vehicle) 3 times daily over a 5-day period. On day 6, serotonin was applied by iontophoresis within the pretreated skin. After another 1-week break, the treatments were performed vice versa on the corresponding infrascapular region. Weal and flare areas were planimetrically evaluated. Itch sensations were documentated by the volunteer on a scale over a 24-min follow-up period. The examination also comprised alloknesis, which stands for induction of perifocal sensations by usually non-itching stimuli. In CAP-treated skin, serotonin-induced wheals were significantly larger post-application compared to non-pretreated skin. Wheals were significantly larger in VS than in UPS. Comparison of serotonin-induced flares in the different study arms did not reveal any significant differences. Itch sensations were not significantly reduced by topical CAP application. The areas of alloknesis were smaller in capsaicin-treated skin compared to VS and UPS, but did not reach significant value. In conclusion, topical CAP application is not effective in serotonin-induced itching in healthy volunteers. Serotonin is most unlikely to play a role in the mechanism of action of CAP.     

Effect of a new topical cyclosporin formulation on human allergic contact dermatitis

We studied the effect of a new topical cyclosporin (CS) formulation on the suppression of allergic contact dermatitis. 4 test sites were outlined on the back of healthy male volunteers. For 7 consecutive days, the test sites were treated as follows: #1: CS formulation (10%), #2: placebo formulation, #3: flumethasone pivalate (FP) formulation (0.02%; #4: no treatment. On day 8, we challenged all test sites in the diphenylcyclopropenone (DCP) sensitized individuals. Photographic and clinical documentation was performed daily. 24 h after the DCP skin challenge, a marked redness accompanied by severe itching and slight pain occurred in the test sites pretreated with CS (#1) and placebo (#2). A considerably milder reaction was noted in the untreated test site (#4) and only a faint redness was noted in the test site pretreated with FP (#3). After 36 h, a further increase in the cutaneous reaction was documented in CS and placebo pretreated test sites (#1, 2). In agreement with other workers, topical CS did not suppress experimentally-induced allergic contact dermatitis in man. On the contrary, in CS and placebo pretreated areas (#1, 2), an increased cutaneous reaction was observed. This observation may be explained by the extensive pretreatment with the topical formulation of CS and placebo, which possibly caused a profound perturbation of the stratum corneum, enabling excessive allergen penetration compared to the untreated area with intact stratum corneum.     

Antipruritic effects of two different 5-HT3 receptor antagonists and an antihistamine in haemodialysis patients

Pruritus is the most distressing symptom in haemodialysis (HD) patients. Its aetiology has not yet been delineated, and thus there are no good therapeutical options. Case reports and series attribute antipruritic potency to the serotonin receptor antagonists of the 5-HT3 type in renal pruritus. It was the aim of this study to investigate the antipruritic effect of two different 5-HT3 receptor antagonists and an antihistamine in 11 patients undergoing HD. Pruritus was induced by iontophoresis with serotonin and histamine and recorded before and after HD. These data were compared to those obtained after oral pretreatment with the 5-HT3 receptor antagonists tropisetron 5 mg and ondansetron 8 mg and the antihistamine cetirizine 10 mg. Ten healthy volunteers served as a control group. Vasocutaneous parameters (wheal and flare), skin temperature and alloknesis were also determined. Itching in HD patients and controls was not significantly diminished by oral pretreatment with the serotonin receptor antagonists. In controls, but not in HD patients, cetirizine significantly reduced itching, skin temperature and vasocutaneous parameters. Our data additionally demonstrate that there are no significant differences in vasocutaneous parameters, itching and alloknesis in HD patients before and after dialysis. We conclude that 5-HT3 receptor blockers such as tropisetron and ondansetron and the antihistamine cetirizine do not sufficiently reduce serotonin- and histamine-induced itching in haemodialyis patients.     

Evaluation of the efficacy and safety of a CS20® protective barrier gel containing OGT compared with topical aciclovir and placebo on functional and objective symptoms of labial herpes recurrences: a randomized clinical trial

Background Topical or systemic antiviral drugs reduce the duration of herpes simplex virus 1 (HSV‐1) recurrences but may not alleviate functional symptoms. Objectives To assess the efficacy and safety of CS20 (Acura 24^®) protective barrier gel versus topical aciclovir and placebo in resolving functional symptoms in HSV‐1 labial recurrences. Methods A prospective, randomized, single‐centre, assessor‐blinded study of CS20 versus topical aciclovir or placebo. The primary endpoint was the total score of four herpes‐related functional symptoms (pain, burning, itching, and tingling sensations), evaluated by visual analogue scale (VAS). Secondary endpoints encompassed objective skin changes (oedema, crusting and erythema), evaluated by specific clinical scores. Results In a study of 106 patients, compared with placebo, a significant improvement in total functional symptom score was observed after 1 day of treatment in the CS20 group, but only after 7 days of treatment in the topical aciclovir group. Burning sensations were significantly reduced by CS20 compared with aciclovir (Days 1–2) or placebo (Days 1–7). Compared to placebo, CS20 significantly reduced pain intensity on Days 1–6. CS20 induced significant and early improvements in the clinical scores for oedema and crusting compared with placebo. Time to cure was similar for CS20 and aciclovir. The treatments were well tolerated and adverse events were comparable in the three treatment groups. Limitations The single‐centre and single‐blind design of the study and the preselection of patients. Conclusion CS20 showed superior effectiveness against functional symptoms (pain and burning) associated with HSV‐1 labial recurrences and was similar to aciclovir for time to cure.     

Antipruritic and thermal sensation effects of hydrocortisone creams in human skin

Few studies evaluate the effect of topical corticosteroids on thermal sensation and in alleviation of itch produced by intradermal injection of histamine. We evaluated the antipruritic effect of hydrocortisone (1% and 2.5%) on histamine-induced itch and sensory effects by measuring itch magnitude, itch duration and thermal thresholds using a computerized thermal sensory analyzer (TSA). This was a double-blind, random, comparative, controlled, single-dose and single-center study. Itch was experimentally induced in both forearms by intracutaneous injection of histamine in 18 subjects. Hydrocortisone 1%, 2.5% and placebo were applied to test sites on both forearms. The thermal threshold for warmth sensation, cold sensation, cold and heat pain was measured with the TSA. Itch magnitude was measured each minute after histamine injection for 10 min with a visual analogue scale (VAS). Itch duration was also recorded. In comparison to placebo, 2.5% hydrocortisone significantly (p = 0.03) reduced itch duration from 12.6 +/- 11.0 min (mean +/- SD) to 8.6 +/- 8.2 min (the reducing rate was 32%) as well as itch magnitude (at minutes 3, 6, 7 and overall). Placebo, 1% and 2.5% hydrocortisone significantly altered (p <0.05) the cold sensation threshold. No treatment altered cold or heat pain thresholds. These data suggest that topical application of 2.5% hydrocortisone may be significantly beneficial for the treatment of histamine-induced itch. The correlation between thermal measurements and antipruritic effects warrants further study.     

5%咪喹莫特乳膏治疗尖锐湿疣的临床研究

目的探讨5%咪喹莫特乳膏治疗尖锐湿疣的有效性和安全性。方法采用多中心、随机、双盲、安慰剂平行对照法对236例尖锐湿疣患者进行了8周的临床研究。结果有116例治疗组患者和120例对照组患者完成临床观察并纳入统计分析。两组治疗后2周、6周及治疗后8周在疗效评价方面有显著差异(P<0.05),不良反应主要是轻至中度的红斑、水肿、糜烂、刺痛及瘙痒。结论5%咪喹莫特乳膏是一种治疗外生殖器疣有效而安全的新药。     

Effects of cetirizine and epinastine on the skin response to histamine iontophoresis

Epinastine and cetirizine are second-generation, nonsedating and long-lasting antihistamines that are now frequently used for the allergic disorders. We have examined the inhibitory effects of these two drugs on the histamine-induced flare and wheal responses using iontophoresis at 1, 2, 4, 8 and 24 h after the oral administration by a double-blind, cross-over and placebo-controlled study. Both cetirizine and epinastine significantly inhibited the histamine-induced flare and wheal responses at 2 h after the oral administration when compared with placebo. The inhibitory effects of cetirizine and epinastine on the flare response lasted long until at 24 h, however, epinastine was less potent than cetirizine. The inhibitory effects on the wheal response was also clearly and significantly evident at 2-8 h by cetirizine and epinastine. At 24 h cetirizine only showed the significant inhibition on the histamine-induced wheal response. In contrast, epinastine seemed to exhibit the inhibitory capacity earlier than did cetirizine. The inhibitory action of the drugs on the histamine-induced wheal response peaked at 4 h after the oral administration. The histamine-induced itch sensation was also markedly or completely suppressed at 2-8 h by the drugs. Thus, both drugs exhibited the potent and long-lasting antihistamine activity on the skin responses induced by histamine iontophoresis.     

Effect of acupuncture on experimentally induced itch

We evaluated the effect of acupuncture on histamine-induced itch and flare in healthy volunteers (n = 25) and compared it with the effect of a pseudo-acupuncture procedure and of no-intervention in a single-blind randomized cross-over study. A cumulative itch index is defined and was found to be smaller with acupuncture than with either pseudo-acupuncture (p less than 0.02) or with no-intervention (p less than 0.005). The duration of itching was shorter with acupuncture than with either pseudo-acupuncture (p = 0.006) or with no-intervention (p less than 0.001). In addition, maximal flare area was decreased with acupuncture compared with pseudo-acupuncture (p less than 0.04) and with no intervention (p = 0.003). Acupuncture had little or no effect on the itch onset time or on the maximal itch intensity after intradermal injection of histamine. Measurements of itching correlated poorly with measurements of flare size in all three experimental groups. Acupuncture appears to be an effective inhibitor of histamine-induced itch and flare. Moreover, acupuncture points displayed specificity in that needling near-by, non-acupuncture sites resulted in greater itching and larger flares.     

Behandlung der Kopfhaut-Psoriasis

BACKGROUND: The scalp is a problematic area in psoriasis where treatment is often difficult. The lesions often extend beyond the hairline to involve the forehead, neck and sensitive facial skin. Topical corticosteroids and potentially irritant topical preparations have only limited utility in these sensitive areas. Most of the patients additionally suffer from psychosocial problems due to the visibility of lesions. OBJECTIVE: The aim of this multicenter, prospective, randomized, double-blind study, was to assess efficacy, safety and tolerability of once daily tacalcitol emulsion (4 micro g/g) compared to placebo in the treatment of scalp psoriasis. METHODS: To determine efficacy, safety and tolerability, 273 patients with mild to moderate scalp psoriasis were treated over a 8-week period. Response to treatment was evaluated using the sum score of erythema, infiltration and scaling. Global improvement of psoriasis was rated by the investigators and the patients using a 5-point scale. In addition the single scores of erythema, infiltration and scaling were assessed by the investigators, and the patients were asked to evaluate the intensity of itching and scaling over the treatment period. RESULTS: Tacalcitol was significantly superior to placebo in reducing the severity of scalp psoriasis. At the end of the study, the median sum score decreased by 53% in the tacalcitol group and was significantly better than placebo with 30% (p<0.0001). Global assessment of improvement was significantly greater in the tacalcitol group in both investigator and patient evaluation. 80% of patients on tacalcitol showed improvement to clearance and was statistically significant better than placebo (p <0.0001) in the investigator rating after 8 weeks. Tacalcitol was significantly superior to placebo in reducing erythema, scaling and infiltration, and in the patient assessment in reducing scalp scaling and itching. Treatment was very well tolerated. Local reactions were transient and uncommon. Their incidence was similar in both treatment groups. No serious side effects were reported, including those relating to calcium homeostasis or vitamin D(3) metabolism. No changes in mean levels of serum calcium, parathyroid hormone (PTH), calcitriol and in 24h-urinary excretion were observed. CONCLUSION: The results of this study indicate that topical application of tacalcitol (4 micro g/g) emulsion once daily is an effective, safe and very well- tolerated treatment for scalp psoriasis.     

Does topical minoxidil increase skin blood flow? A laser Doppler flowmetry study

Cutaneous blood flow was measured by Laser Doppler Flowmetry after topical application of minoxidil lotion, in 9 healthy males with androgenetic alopecia, and other volunteers. No reaction in the cutaneous blood flow was seen after application of 2%, 5%, or placebo minoxidil lotion.     

Clobetasol propionate 0.05% in a novel foam formulation is safe and effective in the short-term treatment of patients with delayed pressure urticaria: a randomized, double-blind, placebo-controlled trial

BACKGROUND: Delayed pressure urticaria (DPU) is characterized by the appearance of typical painful skin lesions (weals) after pressure stimulus. Oral corticosteroids are effective treatments but long-term therapy is problematic. A new topical formulation of clobetasol propionate 0.05% in thermophobic foam (CF) (Olux) has recently become available. The foam is easy to apply, with low skin residues. OBJECTIVES: To evaluate in a double-blind placebo-controlled trial the efficacy, tolerability and safety of CF in the topical treatment of DPU. METHODS: Twenty-six subjects with a positive history of DPU (13 men, mean age 44 years) were enrolled in a 4-week trial. CF or the corresponding placebo were applied twice daily. Drug application was performed in the most affected areas and in a target area where a standardized pressure challenge test was performed at baseline and at week 4. Efficacy was evaluated by scoring skin lesions regarding erythema, oedema and itching (0, no sign; 4, severe signs) and by calculating the area of the pressure challenge-induced lesion. Safety was evaluated by measuring plasma levels of adrenocorticotropic hormone (ACTH) and cortisol. RESULTS: CF significantly (P = 0.0001) reduced lesion area by 84% in comparison with baseline values and by 97% in comparison with the placebo group values. Lesion area in the CF group was reduced from 144 cm(2) to 21 cm(2) at the end of the study. No significant differences in lesion area and clinical lesion scores were observed in the placebo group (lesion area 201 cm(2) at baseline; 216 cm(2) after 4 weeks). A significant clinical improvement was observed in all treated skin areas in the CF group. Mean +/- SD erythema score was reduced by CF from 1.8 +/- 0.6 at baseline to 0.6 +/- 0.5 at the end of the treatment (P = 0.001). Similar modifications were observed also for oedema (from 1.6 +/- 0.6 to 0.2 +/- 0.5) and itching score. Nonsignificant modifications of plasma levels of ACTH, cortisol and glucose were observed in both study groups, in comparison with baseline values. No adverse events were recorded during the trial in either treatment group. CONCLUSIONS: CF is effective, safe, convenient and well tolerated in the short-term treatment of DPU.     

Extracto de Polypodium leucotomos en dermatitis atópica: Ensayo multicéntrico,aleatorizado, doble ciego y controlado con placebo

IntroductionTopical corticosteroids are used to treat inflammation and relieve itching in atopic dermatitis, but their use is limited by adverse reactions.ObjectivesThe main aim of this study was to investigate whether daily treatment with Polypodium leucotomos extract would reduce the use of topical corticosteroids in children and adolescents with atopic dermatitis. We also analyzed oral antihistamine use and changes in disease severity.Patients and methodsWe performed a phase IV randomized, double-blind, placebo-controlled, multicenter trial involving 105 patients aged between 2 and 17 years who were receiving topical corticosteroids to treat moderate atopic dermatitis. The patients were randomized to receive, in addition to their standard treatment, Polypodium leucotomos extract or placebo (both in capsule form) for 6 months. The percentage of days on which topical corticosteroids and other atopic dermatitis treatments were used was calculated.ResultsUse of Polypodium leucotomos extract did not significantly reduce the mean (SD) percentage of days on which topical corticosteroids were used (11% [12%] vs 12% [11%] for placebo). A significant reduction was, however, observed for oral histamine use (median percentage of days, 4.5% in the Polypodium leucotomos group and 13.6% in the placebo group [P =  .038]). The percentage of patients who used oral antihistamines was also lower in the Polypodium leucotomos group.ConclusionLong-term treatment with Polypodium leucotomos extract has benefits for children and adolescents with atopic dermatitis who require pharmacologic treatment to reduce inflammation and relieve itching.     

Oxatomide in the treatment of pruritus senilis. A double-blind placebo-controlled trial

The antiallergic drug oxatomide was evaluated in a double-blind placebo-controlled study in 35 patients with pruritus senilis. The trial was run in the wintertime, and the patients were orally given either 30 mg oxatomide b.i.d. (n = 19) or a placebo (n = 16) for 2 months. Complete suppression or marked improvement of the complaints was experienced by 79% of the patients given oxatomide and by 31% of the control patients. Oxatomide was superior to the placebo in reducing both the duration and the severity of itching. The need of additional topical medication was higher in the placebo group. Somnolence and cramps were each reported by 1 oxatomide-treated patient.     

A randomized controlled trial of R‐salbutamol for topical treatment of discoid lupus erythematosus

Background In a recent open pilot trial, R‐salbutamol sulphate, a well‐known molecule with anti‐inflammatory effects, was tested successfully on patients with therapy‐resistant discoid lupus erythematosus (DLE). Objectives To compare the efficacy and safety of R‐salbutamol cream 0·5% vs. placebo on DLE lesions in a multicentre, double‐blinded, randomized, placebo‐controlled phase II trial. Methods Thirty‐seven patients with at least one newly developed DLE lesion were randomized – 19 to the R‐salbutamol cream 0·5% and 18 to placebo – and treated twice daily for 8 weeks. Efficacy was evaluated through scores of erythema, scaling/hypertrophy and induration as well as pain and itching; general improvement scored by the investigator and global improvement scored by patients’ assessment were also evaluated. Results The mean area under the curve of improvement for scaling/hypertrophy, pain, itching and global patient assessment was significantly better for the actively treated patients as compared with placebo (scaling/hypertrophy, P = 0·0262; pain, P = 0·0238; itching, P = 0·0135; global patient assessment, P = 0·045). Moreover, the percentage of patients without induration was significantly higher in the active group compared with the placebo group (P = 0·013), and a statistically significantly greater decrease in the size of the lesional area was also seen in the overall analysis of the R‐salbutamol‐treated patients (P = 0·0197). No serious adverse events were reported. Conclusions Application of R‐salbutamol cream 0·5% was safe and well tolerated. Statistically significant effects were seen on scaling/hypertrophy, induration, pain and itching as well as patient global assessment, suggesting that R‐salbutamol could be a promising new topical therapy alternative for DLE.     

Suppression of histamine-induced pruritus by hydroxyzine and various neuroleptics.

This study evaluates the ability of hydroxyzine and various neuroleptics to suppress histamine-induced pruritus in ten volunteer subjects with the use of a double-blind crossover protocol. The itch threshold was determined in each volunteer by intradermal injection of gradually increasing concentrations of histamine. Volunteers were then given the study drugs and placebo at the same interval of time, under near identical conditions, and the itch threshold was determined. Thiothixene, hydroxyzine hydrochloride, chlorpromazine, thioridazine, and a lactose placebo were evaluated. Compared to other drugs, hydroxyzine alone was more effective in the suppression of histamine-induced itch. Consequently, hydrozyzine may be more effective in histamine-induced pruritus. The neuroleptic drugs used in this study do not significantly suppress histamine-induced pruritus, but they may be beneficial in nonhistamine-induced pruritus or psychogenic pruritus.     

Efficacy of combined treatment with oral and topical acyclovir in first episode genital herpes.

Fifty patients presenting with first episode genital herpes were randomly allocated to seven day treatment with either oral acyclovir plus 5% acyclovir cream or oral acyclovir plus matching placebo cream. Combined treatment with oral and topical acyclovir was associated with a shorter duration of itching in women alone (p = 0.04) but gave no clinical relief of other symptoms, the time to healing of lesions, or the subsequent recurrence rate. Concomitant topical treatment with 5% acyclovir cream confers no advantages on patients who receive oral acyclovir.     

Noxious heat and scratching decrease histamine-induced itch and skin blood flow

The aim of this study was to assess the effect of thermal stimuli or distal scratching on skin blood flow and histamine-induced itch in healthy volunteers. Twenty-one healthy volunteers participated in the study. Baseline measurements of skin blood flow were obtained on the flexor aspect of the forearm. These measurements were compared with skin blood flow after various stimuli: heating the skin, cooling the skin, noxious cold 2 degrees C, noxious heat 49 degrees C, and scratching via a brush with controlled pressure. Afterwards histamine iontophoresis was performed and skin blood flow and itch intensity were measured immediately after the above-mentioned stimuli. Scratching reduced mean histamine-induced skin blood flow and itch intensity. Noxious heat pain increased basal skin blood flow but reduced histamine-induced maximal skin blood flow and itch intensity. Cold pain and cooling reduced itch intensity, but neither affected histamine-induced skin blood flow. Sub-noxious warming the skin did not affect the skin blood flow or itch intensity. These findings suggest that heat pain and scratching may inhibit itch through a neurogenic mechanism that also affects skin blood flow.     

Effects of bepotastine, cetirizine, fexofenadine, and olopatadine on histamine-induced wheal-and flare-response, sedation, and psychomotor performance

Although many antihistamines are now in clinical use, few studies directly compare their pharmacodynamic and sedative activities in humans in vivo. We designed a double-blind, placebo-controlled, crossover study to compare the inhibitory effects of bepotastine, cetirizine, fexofenadine, and olopatadine on histamine-induced flare-and-wheal response. Systemic sedative effects and impaired psychomotor activities by these drugs were also evaluated. Bepotastine (10 mg twice a day), cetirizine (10 mg once a day), fexofenadine (60 mg twice a day), and olopatadine (5 mg twice a day) or placebo was given in a double-blind manner to seven healthy volunteers before histamine challenge by iontophoresis. At 0, 1, 2, 4, 8, 12, and 24 h following the oral administration of these drugs, histamine iontophoresis-induced wheal-and-flare response was measured. Sedative effects by the drugs were also evaluated by a visual analogue scale for subjective sedation, and by word processor test for psychomotor activity. Each volunteer was tested with all of the drugs (including placebo), administered in a random order with a washout period of at least 1 week. Histamine iontophoresis induced marked wheal-and-flare response in all participants. Bepotastine, cetirizine, fexofenadine, and olopatadine yielded significant reduction of histamine-induced wheal-and-flare response compared to placebo (P < 0.01). Among the drugs, olopatadine and cetirizine suppressed most markedly and persistently histamine-induced wheal-and-flare response, while bepotastine and fexofenadine produced a significant, but less persistent suppression. Olopatadine, fexofenadine, and cetirizine showed a significant systemic sedative effect in this order with bepotastine showing the least sedative effect. Moreover, olopatadine affected psychomotor performance most markedly, which was followed by fexofenadine and cetirizine. These results indicate that bepotastine, cetirizine, fexofenadine, and olopatadine inhibit histamine-induced wheal-and-flare response of humans in vivo and induce a variable systemic sedative effect and impaired psychomotor activity. Although olopatadine and cetirizine showed the strongest and most persistent suppression of histamine-induced wheal-and-flare response, olopatadine showed a considerable sedative effect with impaired psychomotor performance.     

Screening topical antipruritics: a histamine-induced itch human model

Itch is a subjective symptom; its magnitude (intensity) may be only estimated by the reports of patients or volunteers. We utilized a comparative screening method to identify and quantify the efficacy of topical antipruritics with a histamine-induced itch human model. Ten individuals responsive to histamine-induced itch sensation were enrolled. Both forearms served as test sites. Each test site was treated randomly either by histamine injection only or pretreated with a coded candidate formula for 30 min and then a histamine injection. Itch was experimentally induced in each test site by the intracutaneous injection of 100 microg histamine dihydrochloride dissolved in 1 ml normal saline. Itch magnitude was measured each minute after histamine injection for 20 min with a magnitude visual analogue scale. Itch duration was also recorded. Formulation D significantly (p < 0.05) decreased itch magnitude (within a 20-min test period), from 2.6 +/- 2.1 cm (mean +/- SD) to 2.2 +/- 2.1 cm (mean +/- SD) when compared to its vehicle control; it also significantly (p < 0.05) shortened itch duration (15.0 +/- 7.4 min; mean +/- SD) in comparison with its vehicle control (20.3 +/- 7.0 min; mean +/- SD). Of all the formulations tested, formulation D was the most effective antipruritic in decreasing histamine-induced itch. This method may act as a simple and robust screening procedure when evaluating potential antipruritics and allow a comparison among products. Until validated with disease-induced itch, e.g., atopic dermatitis, the model should be considered screening in nature.