Antipruritic effect of the topical phosphodiesterase 4 inhibitor E6005 ameliorates skin lesions in a mouse atopic dermatitis model

Roflumilast Cream, 0.15%, for Atopic Dermatitis in Adults and Children: INTEGUMENT-1 and INTEGUMENT-2 Randomized Clinical Trials

Importance

Safe, effective, and well-tolerated topical treatment options available for long-term use in patients with atopic dermatitis (AD) are limited and associated with low adherence rates.

Objective

To evaluate efficacy and safety of once-daily roflumilast cream, 0.15%, vs vehicle cream in patients with AD.

Design, Setting, and Participants

Two phase 3, randomized, double-blind, vehicle-controlled trials (Interventional Trial Evaluating Roflumilast Cream for the Treatment of Atopic Dermatitis 1 and 2 [INTEGUMENT-1 and INTEGUMENT-2]), included patients from sites in the US, Canada, and Poland. Participants were 6 years or older with mild to moderate AD based on Validated Global Assessment for Atopic Dermatitis (assessed on a 5-point scale ranging from 0 [clear] to 4 [severe]).

Intervention

Patients were randomized 2:1 to receive roflumilast cream, 0.15%, or vehicle cream once daily for 4 weeks.

Main Outcomes and Measures

The primary efficacy end point was Validated Investigator Global Assessment for Atopic Dermatitis success at week 4, defined as a score of 0 or 1 plus at least a 2-grade improvement from baseline. Secondary end points included Eczema Area and Severity Index and Worst Itch Numeric Rating Scale. Safety and local tolerability were also evaluated.

Results

Among 1337 patients (654 patients in INTEGUMENT-1 and 683 patients in INTEGUMENT-2), the mean (SD) age was 27.7 (19.2) years, and 761 participants (56.9%) were female. The mean body surface area involved was 13.6% (SD = 11.6%; range, 3.0% to 88.0%). Significantly more patients treated with roflumilast than vehicle achieved the primary end point (INTEGUMENT-1: 32.0% vs 15.2%, respectively; P < .001; INTEGUMENT-2: 28.9% vs 12.0%, respectively; P < .001). At week 4, statistically significant differences favoring roflumilast also occurred for the achievement of at least 75% reduction in the Eczema Area and Severity Index (INTEGUMENT-1: 43.2% vs 22.0%, respectively; P < .001; INTEGUMENT-2: 42.0% vs 19.7%, respectively; P < .001). Roflumilast was well tolerated with low rates of treatment-emergent adverse events. At each time point, investigators noted no signs of irritation at the application site in 885 patients who were treated with roflumilast (≥95%), and 885 patients who were treated with roflumilast (90%) reported no or mild sensation at the application site.

Conclusions and Relevance

In 2 phase 3 trials enrolling adults and children, once-daily roflumilast cream, 0.15%, improved AD relative to vehicle cream, based on multiple efficacy end points, with favorable safety and tolerability.

Trial Registration

ClinicalTrials.gov Identifiers: NCT04773587, NCT04773600.

PDE4D: A Multipurpose Pharmacological Target

Phosphodiesterase 4 (PDE4) enzymes catalyze cyclic adenosine monophosphate (cAMP) hydrolysis and are involved in a variety of physiological processes, including brain function, monocyte and macrophage activation, and neutrophil infiltration. Among different PDE4 isoforms, Phosphodiesterases 4D (PDE4Ds) play a fundamental role in cognitive, learning and memory consolidation processes and cancer development. Selective PDE4D inhibitors (PDE4Dis) could represent an innovative and valid therapeutic strategy for the treatment of various neurodegenerative diseases, such as Alzheimer's, Parkinson's, Huntington's, and Lou Gehrig's diseases, but also for stroke, traumatic brain and spinal cord injury, mild cognitive impairment, and all demyelinating diseases such as multiple sclerosis. In addition, small molecules able to block PDE4D isoforms have been recently studied for the treatment of specific cancer types, particularly hepatocellular carcinoma and breast cancer. This review overviews the PDE4DIsso far identified and provides useful information, from a medicinal chemistry point of view, for the development of a novel series of compounds with improved pharmacological properties.

Effect of Roflumilast Cream (ARQ-151) on Itch and Itch-Related Sleep Loss in Adults with Chronic Plaque Psoriasis: Patient-Reported Itch Outcomes of a Phase 2b Trial

BACKGROUND

Itch is the most bothersome symptom reported by patients with psoriasis. Safe and effective treatments for psoriasis that also address itch are needed.

OBJECTIVES

To report effects of roflumilast cream on itch-related outcomes from a Phase 2b trial.

METHODS

Adults with chronic plaque psoriasis were randomized to roflumilast 0.3%, roflumilast 0.15%, or vehicle once-daily for 12 weeks. Psoriasis severity was assessed via the Investigator Global Assessment (IGA; a 5-point scale assessing plaque thickening, scaling, and erythema ranging from 0 [clear] to 4 [severe]) and ≥ 2 on a modified Psoriasis Area and Severity Index (PASI-HD, which combines severity of lesions and area affected, ranging from 0 [no disease] to 72 [maximal disease], with the actual percentage of the anatomical area involved in those patients with < 10% of anatomical area involved [e.g., 0.1 for 1% to 0.9 for 9%]). Itch was evaluated via Worst Itch Numeric Rating Scale (WI-NRS), Psoriasis Symptom Diary (PSD) Items 1 (severity of itch) and 2 (bother of itch), and itch-related sleep loss NRS scores. Post hoc correlation analyses between WI-NRS and PASI, WI-NRS and itch-related sleep loss, and WI-NRS and DLQI were also performed.

RESULTS

Roflumilast-treated patients had significantly greater improvements than vehicle-treated patients in WI-NRS and PSD Items 1 and 2 beginning at Week 2 and in itch-related sleep loss Weeks 6 through 12. Among patients with baseline WI-NRS ≥ 6, significantly more patients achieved ≥ 4-point improvement with roflumilast than with vehicle as early as Week 2. Itch severity had low correlation with PASI while WI-NRS and IGA were not always aligned.

LIMITATIONS

The first assessment was at 2 weeks, limiting the ability to assess early onset of itch response.

CONCLUSION

Roflumilast cream improved itch and itch-related sleep loss associated with chronic plaque psoriasis.

CLINICALTRIALS

GOV IDENTIFIER

NCT03638258.

Safety profile and tolerability of topical phosphodiesterase 4 inhibitors for the treatment of atopic dermatitis: A systematic review and meta-analysis

Objective

Methods

Results

Conclusions

Phosphodiesterase‑4 inhibitors: a review of current developments (2013-2021)

INTRODUCTION

Cyclic nucleotide phosphodiesterase 4 (PDE4) is responsible for the hydrolysis of cAMP, which has become an attractive therapeutic target for lung, skin, and severe neurological diseases. Here, we review the current status of development of PDE4 inhibitors since 2013 and discuss the applicability of novel medicinal-chemistry strategies for identifying more efficient and safer inhibitors.

AREAS COVERED

This review summarizes the clinical development of PDE4 inhibitors from 2013 to 2021, focused on their pharmacophores, the strategies to reduce the side effects of PDE4 inhibitors and the development of subfamily selective PDE4 inhibitors.

EXPERT OPINION

To date, great efforts have been made in the development of PDE4 inhibitors, and researchers have established a comprehensive preclinical database and collected some promising data from clinical trials. Although four small-molecule PDE4 inhibitors have been approved by FDA for the treatment of human diseases up to now, further development of other reported PDE4 inhibitors with strong potency has been hampered due to the occurrence of severe side effects. There are currently three main strategies for overcoming the dose limitation and systemic side effects, which provide new opportunities for the clinical development of new PDE4 inhibitors.

Differential Diagnosis and Treatment of Itching in Children and Adolescents

Itching is prevalent in children with skin disorders and associated with effects on their mood, quality of life, and social functioning. Surprisingly, there are no data on childhood prevalence of pruritus in the general population. The aim of this article is to explore the epidemiology, clinical manifestation, and treatment for itch (pruritus) in the pediatric population (from infancy to adolescence), and to be helpful to primary care physicians who assess and diagnose pediatric patients with itching. In this study, we searched for specific keywords using PubMed and MEDLINE (Ovid) and, then, refined the retrieved searches for each cause and treatment. As a result of reviewing the literature, atopic dermatitis was shown to be the most common cause of itching, especially during infancy and through preschool. Not only skin disorders but also systemic diseases, drugs, and postburn states can predispose an individual to itching in childhood. There are traditional and newly developed treatment modalities for itching in pediatric patients. However, because the pharmacokinetics and pharmacodynamics of childhood are different from those of adults, the medications for itching have to be applied carefully for these age groups. There are many areas to be elucidated regarding the prevalence and objective assessment of pruritus in pediatric patients. Moreover, the safety profiles of medications in the pediatric population need to be better understood. Further studies to investigate itching in childhood are warranted.

Anti-inflammatory effects of a novel phosphodiesterase-4 inhibitor, AA6216, in mouse dermatitis models

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is commonly treated with corticosteroids. However, these drugs have long-term adverse effects, representing an unmet need for new treatments. AD is associated with dysregulation of phosphodiesterase 4 (PDE4) activity in inflammatory cells and the topical PDE4 inhibitor, crisaborole, is approved by the US FDA for mild-to-moderate AD. In this study, we compared the effects of a novel PDE4 inhibitor, AA6216, with those of crisaborole on skin inflammation. We found that AA6216 is a more potent inhibitor of PDE4 and of cytokine production (TNF-α, IL-12/23p40, IL-4, IL-13, and IFN-γ) by human peripheral blood mononuclear cells (PBMCs) stimulated by phytohemagglutinin (PHA) or anti-CD3 antibodies, with IC₅₀ values ranging from 5.9 to 47 nM. AA6216 also significantly suppressed skin inflammation in three mouse models of dermatitis. In acute and chronic oxazolone-induced dermatitis models, topical AA6216 exhibited stronger inhibitory effects on ear inflammation and cytokine production (TNFα, IL-1β, and IL-4) in skin lesions compared with crisaborole. In a Dermatophagoides farinae-induced dermatitis model, AA6216 significantly reduced the dermatitis score, based on the development of erythema/hemorrhage, scarring/dryness, edema, and excoriation/erosion, compared with a clinically used topical AD drug, tacrolimus. These results suggest the possibility that AA6216 is a novel and effective topical therapeutic agent for the treatment of dermatitis including AD.

Advances in the Development of Phosphodiesterase-4 Inhibitors

Cyclic nucleotide phosphodiesterase 4 (PDE4) specifically hydrolyzes cyclic adenosine monophosphate (cAMP) and plays vital roles in biological processes such as cancer development. To date, PDE4 inhibitors have been widely studied as therapeutics for the treatment of various diseases such as chronic obstructive pulmonary disease, and many of them have progressed to clinical trials or have been approved as drugs. Herein, we review the advances in the development of PDE4 inhibitors in the past decade and will focus on their pharmacophores, PDE4 subfamily selectivity, and therapeutic potential. Hopefully, this analysis will lead to a strategy for development of novel therapeutics targeting PDE4.

Small molecule drugs for the treatment of pruritus in patients with atopic dermatitis

Chronic pruritus is a cardinal symptom of the inflammatory skin disease atopic dermatitis (AD). Pathogenic mechanisms in the periphery, spinal cord and the brain have been implicated in AD-related pruritus. Therefore, both systemic and topical administration of drugs could potentially provide relief. Despite efforts to elucidate the mechanisms behind AD-related pruritus and the relative contribution of peripheral nervous system and central nervous system (CNS), specific and successful treatment options have not yet been developed. Several small molecule drugs are currently being investigated to treat AD and AD-related pruritus. These small molecule drugs can be applied systemically but also topically, as they are able to penetrate into the skin due to their small size. Small molecule drugs specifically targeting peripheral itch transmission, e.g. peripherally selective κ-opioid receptors agonists and neurokinin 1 receptors antagonists, have so far been unable to improve AD-related pruritus when applied systemically, possibly because of the lack of CNS activity. Current evidence from clinical and preclinical trials with centrally acting or peripherally selective oral κ-opioid receptors agonists implies that CNS activity is required for an antipruritic effect. CNS activity is, however, directly associated with CNS-mediated side-effects. On the other hand, topical application of small molecules with anti-inflammatory activity such as Janus kinase inhibitors and phosphodiesterase 4 inhibitors, and also of κ-opioid receptor agonists, has shown promising results regarding their ability to reduce AD-related pruritus. In conclusion, topical application of anti-inflammatory compounds appears to be a highly promising strategy for the treatment of AD-related pruritus.

Oleic acid as the active agent and lipid matrix in cilomilast-loaded nanocarriers to assist PDE4 inhibition of activated neutrophils for mitigating psoriasis-like lesions

Both phosphodiesterase (PDE4) inhibitors and omega-9 fatty acids show anti-inflammatory activity for treating inflamed skin diseases, but their efficacy remains low. Combinatorial agents are anticipated to offer an advanced strategy for efficient therapy. We prepared cilomilast-loaded oleic acid (OA) nanocarriers to test the inhibitory capability against human neutrophil stimulation and a murine psoriasis model. OA played dual roles in the nanocarriers as both the active ingredient and lipid matrix in the nanoparticulate core. OA nanoparticles but not free OA could restrain calcium mobilization in activated neutrophils. The inhibition level of superoxide anion and elastase by cilomilast-loaded OA nanocarriers approximated that of free forms. In the mouse model, the intradermal nanosystems reduced imiquimod-induced epidermal thickening from 230.4 to 63.1 μm. Transepidermal water loss was decreased from 30.2 to 11.3 g/m²/h by integrated nanocarriers. The nanosystems mitigated neutrophil infiltration and hyperproliferation in the psoriasiform lesion via decreased expression of cytokines and chemokines. STATEMENT OF SIGNIFICANCE: The long-term therapy for psoriasis is unsatisfactory due to the possible adverse effects and inefficiency after prolonged use. Both phosphodiesterase (PDE4) inhibitors and omega-9 fatty acids such as oleic acid (OA) show anti-inflammatory activity for treating inflamed skin diseases. Combinatorial agents are anticipated to offer an advanced strategy for efficient therapy. OA is also ideal for incorporation into nanoparticles to enhance particulate emulsification, drug entrapment, and biocompatibility. We prepared cilomilast-loaded oleic acid (OA) nanocarriers to test the inhibitory capability against human neutrophil stimulation and a murine psoriasis lesion. OA nanocarriers are indigenous to prevent neutrophil activation and the deterioration of psoriatic lesion. Cilomilast incorporation in OA nanocarriers could further mitigate the clinical score and suppressing proinflammatory mediators.

Advances in atopic dermatitis in 2017

This review encompasses relevant scientific and clinical advances in atopic dermatitis (AD) published in 2017. These include articles from the Journal of Allergy and Clinical Immunology, as well as other prominent publications that have contributed to the emerging field, on the microenvironment of the skin and molecular patterns guiding biologic treatment strategies. The most commonly questioned and explored themes of the year included the effect of the microbiome on AD development, as well as cell signaling and symptom severity. Topics also included the description of patient-specific molecular endotypes within the larger population with AD. All of these factors will create potential opportunities to guide personalized therapy with the broadening array of topical and systemic interventions currently available, as well as providing new insights to guide the development of novel molecularly targeted therapeutics. With recent US Food and Drug Administration approval of the first wave of new targeted therapies for AD, additional information exploring the safety profiles and long-term effects of these medications was also at the forefront in 2017.

Phosphodiesterase-4 Inhibitors for the Treatment of Inflammatory Diseases

Phosphodiesterase-4 (PDE4), mainly present in immune cells, epithelial cells, and brain cells, manifests as an intracellular non-receptor enzyme that modulates inflammation and epithelial integrity. Inhibition of PDE4 is predicted to have diverse effects via the elevation of the level of cyclic adenosine monophosphate (cAMP) and the subsequent regulation of a wide array of genes and proteins. It has been identified that PDE4 is a promising therapeutic target for the treatment of diverse pulmonary, dermatological, and severe neurological diseases. Over the past decades, numerous PDE4 inhibitors have been designed and synthesized, among which roflumilast, apremilast, and crisaborole were approved for the treatment of inflammatory airway diseases, psoriatic arthritis, and atopic dermatitis, respectively. It is regrettable that the dramatic efficacies of a drug are often accompanied by adverse effects, such as nausea, emesis, and gastrointestinal reactions. However, substantial advances have been made to mitigate the adverse effects and obtain better benefit-to-risk ratio. This review highlights the dialectical role of PDE4 in drug discovery and the disquisitive details of certain PDE4 inhibitors to provide an overview of the topics that still need to be addressed in the future.

Adult atopic dermatitis: new and emerging therapies

INTRODUCTION

Adult atopic dermatitis (AD) is very difficult to manage. Indeed, AD in adults is frequently refractory to topical treatment, especially with regards to the persistent form. Therefore, long-term treatment with oral immunosuppressive therapy is often required to control the burden of the disease, prevent flare-ups and achieve better patient quality of life outcomes. Areas covered: In the last decade the better understanding of AD pathogenesis has been used to improve treatment strategies with many emerging therapeutics options. Epidermal barrier impairment often plays the initial role in the initiation of the disease. Moreover, T helper 2 cytokines interleukin (IL)-4 and IL-13 and their downstream effects are prominent in AD, with pleiotropic effects on the innate and adaptive immune system. Targeting these cells, their products or receptors appears to be a reasonable therapeutic strategy. Expert commentary: In the next years, many therapeutic options for adult AD will be available. Clinical trials showed that JAK inhibitors, PDE-4 inhibitors and monoclonal antibodies against some IL (IL-4, IL 13, IL-17, IL-22, IL-31) seem to be the most promising drugs, but dermatologists will have to evaluate their effectiveness and safety in clinical practice.

Topical E6005/RVT-501, a novel phosphodiesterase 4 inhibitor, for the treatment of atopic dermatitis

INTRODUCTION

Local adverse effects of steroid use and the burning sensation of calcineurin inhibitors impair patients' adherence to treatment and decrease the treatment response in atopic dermatitis (AD). Steroid phobia appears to be a psychological problem in patients with AD. Topical non-steroidal remedies are in demand. Areas covered: This manuscript reviews the current literature on preclinical and clinical studies regarding topical E6005/RVT-501, a novel phosphodiesterase 4 inhibitor. We also discuss the mechanistic background of E6005/RVT-501 in the treatment of AD. Expert opinion: Topical E6005/RVT-501 improves skin eruption and pruritus of pediatric and adult AD patients without any serious side effects. It is useful for mild to moderate lesions of AD in pediatric and adult patients. Topical E6005/RVT-501 is non-steroidal agent but its potency is equal to that of mild rank topical steroid, therefore, it may fit the demand of patients with steroid phobia. Its steroid-sparing effects may also be investigated in future clinical trials and may minimize the dose and frequency of topical steroids.

Long-term safety of crisaborole ointment 2% in children and adults with mild to moderate atopic dermatitis

BACKGROUND

Long-term topical treatment is often required for atopic dermatitis (AD), a chronic inflammatory skin disease.

OBJECTIVE

To assess the long-term safety results from a multicenter, open-label, 48-week safety study (AD-303) of patients (N = 517) ≥2 years of age with mild to moderate AD who continued crisaborole treatment, a topical phosphodiesterase-4 inhibitor, after completing a 28-day phase 3 pivotal study (AD-301, AD-302).

METHODS

Global disease severity was assessed in patients every 4 weeks, and if assessed as mild or greater, a 28-day treatment period with crisaborole applied twice daily was initiated. Adverse events (AEs), including treatment-emergent AEs (TEAEs), and serious AEs were analyzed.

RESULTS

During the pivotal studies and AD-303, 65% of patients reported ≥1 TEAE, most of which were mild (51.2%) or moderate (44.6%) and considered unrelated to treatment (93.1%). The frequency and severity of TEAEs were consistent. The most frequently reported treatment-related AEs (overall, 10.2%) were dermatitis atopic (3.1%), application-site pain (2.3%), and application-site infection (1.2%). Nine patients (1.7%) discontinued the long-term study because of TEAEs.

LIMITATIONS

Long-term efficacy was not analyzed.

CONCLUSION

Crisaborole ointment had a low frequency of treatment-related AEs over 48 weeks of treatment of patients with AD.

The isozyme selective phosphodiesterase-4 inhibitor, ABI-4, attenuates the effects of lipopolysaccharide in human cells and rodent models of peripheral and CNS inflammation

Inhibitors of phosphodiesterase-4 (PDE4) have been approved for the treatment of inflammatory disorders, but are associated with dose-limiting nausea and vomiting. These side effects are hypothesized to be mediated by inhibition of the PDE4D isozyme. Here we demonstrate the anti-inflammatory effects of the novel brain penetrant PDE4D-sparing PDE4 inhibitor, ABI-4. ABI-4 was a potent (EC₅₀∼14nM) inhibitor of lipopolysaccharide (LPS) induced TNF-α release from mouse microglia and human PBMCs. ABI-4 (0.32mg/kg) blocked LPS-induced release of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) in blood and brain of mice. In a rat model of endotoxin induced uveitis, ABI-4 (0.03-0.3mg/kg) demonstrated steroid-like efficacy in preventing leucocyte infiltration of the aqueous humor when administered 4h after LPS. LPS (0.32mg/kg×5days) caused a 30% upregulation of translocator protein (TSPO) binding which was prevented by co-administration of ABI-4 (0.32mg/kg). In a paradigm to assess motivation, LPS (0.32mg/kg) reduced the number of rewards received, whereas the effect was significantly blunted in mice dosed with ABI-4 (P<0.05) or in PDE4B-/- mice. PDE4B was also shown to modulate brain and plasma levels of TNF-α and IL-1β in aged mice. Aged mice dosed chronically with ABI-4 (0.32mg/kg) as well as aged PDE4B-/- mice, had significantly lower levels of TNF-α and IL-1β in brain and plasma relative to vehicle treated or PDE4+/+ mice. Together these data demonstrate that the PDE4D sparing, PDE4 inhibitor, ABI-4 retains potency and efficacy in exerting anti-inflammatory effects. This mechanism warrants further investigation in human disorders involving neuroinflammation.

A putative antipruritic mechanism of the phosphodiesterase-4 inhibitor E6005 by attenuating capsaicin-induced depolarization of C-fibre nerves

E6005, a potent, selective phosphodiesterase (PDE) 4 inhibitor, has been developed as a novel topical agent of atopic dermatitis (AD). It has been shown to inhibit itching in patients with AD as well in mouse models. To study the mechanism underlying the anti-pruritic effect of E6005, we examined its effect on the activation of dorsal root ganglion (DRG) neurons associated with the itch sensation. Depolarization of DRG neurons by a transient receptor potential vanilloid 1 (TRPV 1) activator, capsaicin was attenuated by E6005 as well as by a 3',5'-cyclic adenosine monophosphate (cAMP) elevator, forskolin. E6005 elevated intracellular levels of cAMP in DRG cells. Taken together, these results suggest that E6005 suppresses TRPV1-mediated C-fibre depolarization through elevation of cAMP levels, thereby exerting an anti-pruritic effect. Thus, E6005 shows the potential to be a new agent for managing pruritus in various skin disorders, including AD.

Safety, tolerability and pharmacokinetics of a novel phosphodiesterase inhibitor, E6005 ointment, in healthy volunteers and in patients with atopic dermatitis

OBJECTIVES

The purpose of the present studies was to assess the safety, tolerability and pharmacokinetics of topical application of a novel phosphodiesterase inhibitor, E6005, in healthy volunteers and in patients with atopic dermatitis (AD).

METHODS

In two randomized, investigator-blind, vehicle-controlled studies, we evaluated the topical application of E6005 ointment at concentrations ranging from 0.01% to 0.2% in healthy volunteers (Study 001) and in patients with AD (Study 101).

RESULTS

Thirty-six subjects were enrolled in Study 001 and 40 in Study 101. Neither skin irritation nor photosensitization was observed with application of E6005 in Study 001. Four subjects receiving E6005 in Study 001 experienced a treatment-emergent adverse event (application site edema, increased alanine aminotransferase or erythema); three of these subjects discontinued the study. Two subjects receiving E6005 in Study 101 experienced an adverse event (gout or enterocolitis); one discontinued the study. Plasma concentrations of E6005 were below the limit of quantification (1 ng/ml) in both studies.

CONCLUSION

E6005 ointment exhibited acceptable safety and tolerability. Topical application of E6005 ointment resulted in very low systemic exposure to E6005 in healthy volunteers and in patients with AD.

An inhaled phosphodiesterase 4 inhibitor E6005 suppresses pulmonary inflammation in mice

Chronic obstructive pulmonary disease (COPD) is a progressive lung disease associated with significant morbidity and mortality. Although several oral phosphodiesterase 4 (PDE4) inhibitors have been developed for the treatment of COPD, their use has been restricted because of side effects including nausea and emesis. We hypothesized that delivery of a dry powdered PDE4 inhibitor by inhalation would minimize systemic absorption and enable local PDE4 inhibition to suppress inflammation within the lung. Neutrophilic pulmonary inflammation was induced in mice by intratracheal administration of lipopolysaccharide. Mice were treated intratracheally with a new dry powder PDE4 inhibitor, E6005 (methyl 4-[({3-[6,7-dimethoxy-2-(methylamino)quinazolin-4-yl]phenyl}amino) carbonyl] benzoate). The pharmacokinetics, cell profiles and levels of cytokines, chemokines, and lipid mediators in bronchoalveolar lavage fluid (BALF), and lung histology were assessed. Intratracheal administration of E6005 to mice resulted in high concentrations of the compound in the lungs. Histological analysis of E6005-treated mice demonstrated reduced inflammation of lung tissue that correlated with a decrease in BALF levels of neutrophils, proinflammatory cytokines, chemokines, and cysteinyl leukotrienes. Thus, intratracheal administration of E6005 effectively suppresses neutrophilic pulmonary inflammation, suggesting that the new inhaled dry powder PDE4 inhibitor represents an alternative to the conventional oral formulation for treating COPD.

Hematocrit-independent recovery is a key for bioanalysis using volumetric absorptive microsampling devices, MitraTM

Background: A novel microsampling device, MitraTM, was evaluated for bioanalysis of E6005 and its O-desmethylated metabolite in human whole blood using an UPLC–MS. Results: A constant volume of blood samples was absorbed onto the tip of Mitra, the analytes were extracted by various solvents and then detected by UPLC–MS. Recovery of the analytes was high in acetonitrile–water (1:1, v/v) but was dependent on hematocrit (Hct) without sonication process, which led to biased accuracy at low and high Hcts. Inclusion of sonication process in extraction improved recovery at high Hct to yield acceptable accuracy across Hcts. Conclusion: Optimization of extraction process to achieve high recovery regardless of Hct is critical in accurate bioanalysis via Mitra.

New innovation of moisturizers containing non-steroidal anti-inflammatory agents for atopic dermatitis

Atopic dermatitis is a chronic, relapsing and extremely pruritic eczematous disease which commonly affects children. The standard management consists of a combination of anti-inflammatory drugs in adjunctive with skin care management particular moisturizer application. A concern for the side effects associated with long term use of corticosteroids has also been considered. There has been an emerging interest in moisturizer containing non-steroidal anti-inflammatory agents such as herbal extracts, vitamins, mineral and lipids. The in vitro and the in vivo studies of each agent were reviewed. The clinical study on the efficacy of moisturizers containing these agents were also demonstrated including the author’s studies and clinical experience. These moisturizers might be considered as an alternative treatment in acute flare of mild to moderate atopic dermatitis.

Antipruritic mechanisms of topical E6005, a phosphodiesterase 4 inhibitor: inhibition of responses to proteinase-activated receptor 2 stimulation mediated by increase in intracellular cyclic AMP

BACKGROUND

Phosphodiesterase 4 (PDE4), which catalyses the conversion of cyclic adenosine 3',5'-monophosphate (cAMP) to 5'-AMP, plays a critical role in the pathogenesis of inflammatory disorders. Pruritus is the main symptom of dermatitides, such as atopic dermatitis, and is very difficult to control. Recent studies have shown that the activation of proteinase-activated receptor 2 (PAR2) is involved in pruritus in dermatoses in humans and rodents.

OBJECTIVE

To investigate the inhibitory effect of E6005, a topically effective PDE4 inhibitor, on PAR2-associated itching in mice.

METHODS

Mice were given an intradermal injection of SLIGRL-NH2 (100 nmol/site), a PAR2 agonist peptide, into the rostral part of the back. E6005 and 8-bromo-cAMP were applied topically and injected intradermally, respectively, to the same site. Scratching bouts were observed as an itch-related behavior, and firing activity of the cutaneous nerve was electrophysiologically recorded. Keratinocytes were isolated from the skin of neonatal mice and cultured for in vitro experiments. The concentrations of cAMP and leukotriene B4 (LTB4) were measured by enzyme immunoassay. The distribution of PDE4 subtypes in the skin was investigated by immunostaining.

RESULTS

Topical E6005 and intradermal 8-bromo-cAMP significantly inhibited SLIGRL-NH2-induced scratching and cutaneous nerve firing. Topical E6005 increased cutaneous cAMP content. Topical E6005 and intradermal 8-bromo-cAMP inhibited cutaneous LTB4 production induced by SLIGRL-NH2, which has been shown to elicit LTB4-mediated scratching. E6005 and 8-bromo-cAMP inhibited SLIGRL-NH2-induced LTB4 production in the cultured murine keratinocytes also. PDE4 subtypes were mainly expressed in keratinocytes and mast cells in the skin.

CONCLUSIONS

The results suggest that topical E6005 treatment inhibits PAR2-associated itching. Inhibition of LTB4 production mediated by an increase in cAMP may be partly involved in the antipruritic action of E6005.