Azathioprine in dermatology: The past, the present, and the future

Pharmacology of drugs used in autoimmune dermatopathies in cats and dogs: A narrative review

Immunosuppressive drugs are the mainstay of treatment for many feline and canine autoimmune skin diseases, either as monotherapy or in combination with other drugs. Treatment with these drugs is often lifelong and may have long-term consequences on the affected animal's overall quality-of-life. Clinicians need to understand the pharmacology of immunosuppressants in planning and executing the treatment regimen for the best possible clinical outcome, as well as reducing the risk of adverse effects. This review paper will focus on the mechanism of action, pharmacokinetics and pharmacodynamics, clinical uses and adverse effects of immunosuppressive drugs used to treat autoimmune dermatoses in cats and dogs. These include glucocorticoids, ciclosporin A, azathioprine, chlorambucil, mycophenolate mofetil, oclacitinib and Bruton's tyrosine kinase inhibitors.

Patch testing while immunosuppressed: potential risks and benefits

INTRODUCTION

Allergic contact dermatitis (ACD) is a common cutaneous inflammatory skin disorder that is diagnosed via epicutaneous patch testing (PT). ACD may also coexist with other systemic inflammatory conditions such as atopic dermatitis and psoriasis. Many of the treatments used to manage severe ACD, along with other systemic conditions, interact with and suppress the immune system, thereby potentially interfering with the mechanism of PT. There is uncertainty in the literature regarding the effects of immunosuppression on the results of PT.

METHODS

A comprehensive literature review was conducted using PubMed and Google Scholar to identify articles relevant to the topic of this review. Only articles available in English were included.

AREAS COVERED

This review discusses the impact of immunomodulating therapies on the results of PT. We summarize the available evidence and provide updated recommendations for several immunomodulating drugs commonly used in patients undergoing PT.

EXPERT OPINION

In general, the results of PT are most reliable when performed without immunosuppression. If this is not feasible, it is best to have patients on as low a dose of immunosuppression as possible, but it may not be necessary to stop or change an immunomodulating drug prior to PT.

Variable Presentations of Photodermatoses - A Case Series

Photodermatoses represent a broad spectrum of skin diseases caused because of exposure to ultraviolet radiation. It is categorized mainly as idiopathic photosensitive disorders, drug or chemical induced photosensitivity reactions, DNA repair-deficiency photodermatoses and photoaggravated dermatoses. Despite being under the photodermatoses umbrella, the pathophysiology of each type of photodermatoses varies. We reported 4 cases of photodermatoses including azathioprine induced pellagra, adult onset actinic prurigo, and photoallergic contact dermatitis due to NSAIDs and cutting fluids. Photoprotection with the usage of photoprotective clothing, broad-spectrum sunscreen application and avoidance of photosensitizing drugs and chemicals are crucial.

Clinical characteristics, diagnosis and management of Sweet syndrome induced by azathioprine

Sweet syndrome is a rare complication of azathioprine treatment with unelucidated clinical features. The purpose of this study was to investigate the clinical characteristics of azathioprine-induced Sweet syndrome (AISS) and provide a reference for diagnosis, treatment and prognosis. We collected relevant case reports of AISS by searching Chinese and English databases from 1960 to December 31, 2022, extracted the data and carried out a retrospective analysis. The median age of the 44 patients was 50 (range 9-89) years, and they included 32 males (72.7%). Fever (86.4%) and arthralgia (31.8%) were the most common clinical symptoms. The skin lesions were mainly pustules (54.5%), papules (40.9%), plaques (40.9%) and nodules (31.8%), which were mainly distributed on the extremities (54.5%), face (38.6%) and hands (36.4%). Laboratory examination revealed neutropenia (65.9%) as well as elevated C-reactive protein (63.6%) and erythrocyte sedimentation (40.9%) rates. Histopathology of the lesioned skin showed neutrophil infiltration (93.2%) and dermal edema (38.6%). Symptom relief was achieved at a median time of 7 days (range 2-28 days) after azathioprine discontinuation in all patients. Nine patients (20.5%) had skin lesions that recurred within 24 h after taking azathioprine again. Clinicians and pharmacists should grasp the regularity and characteristics of AISS and should not recommend the readministration of azathioprine, to avoid the recurrence of Sweet syndrome.

Atopic dermatitis in skin of colour. Part 2: considerations in clinical presentation and treatment options

Recent advances in atopic dermatitis (AD) present the condition as a heterogeneous disease of distinct endotypes across ethnic groups. AD in people with skin of colour may appear psoriasiform, lichenoid, scaly or papular, with a violaceous colour and there is a higher prevalence of post-inflammatory dyspigmentation compared with affected individuals of White ethnicity. These differences in clinical presentation may limit the use of AD assessment tools in people with skin of colour, leading to the potential for misdiagnosis and underestimation of severity, particularly in relation to assessment of erythema. Recent targeted therapies for AD have been studied in multiple ethnic groups; however, ethnicity-based subgroup analysis is often not performed. Further research is required to understand whether treatment responses or safety may differ among ethnic groups.

Potential Therapeutic Approaches for Chronic Urticaria: Beyond H1-Antihistamines and Biologics

Chronic urticaria is a disease that can significantly impact a patient's quality of life and ability to function. There are effective treatment options, such as nonsedating antihistamines or biologics, but some patients do not respond to these therapies, or the therapies are not available or affordable to all patients. This review aims to summarize potential treatment strategies for patients (1) who do not respond to antihistamines and (2) cannot readily access or do not respond to biologics. The review emphasizes the importance of sound clinical practice, including correct diagnosis of chronic urticaria phenotypes, treatment of associated comorbidities, and consideration of add-on pharmacological and nonpharmacological approaches. Although some treatments may lack high-quality evidence, they may still be justifiable in certain cases, provided that there is shared decision-making, regular reassessment, and early recognition of adverse events.

Research progress on pathogenesis and clinical treatment of neuromyelitis optica spectrum disorders (NMOSDs)

Neuromyelitis optica spectrum disorders (NMOSDs) are characteristically referred to as various central nervous system (CNS)-based inflammatory and astrocytopathic disorders, often manifested by the axonal damage and immune-mediated demyelination targeting optic nerves and the spinal cord. This review article presents a detailed view of the etiology, pathogenesis, and prescribed treatment options for NMOSD therapy. Initially, we present the epidemiology of NMOSDs, highlighting the geographical and ethnical differences in the incidence and prevalence rates of NMOSDs. Further, the etiology and pathogenesis of NMOSDs are emphasized, providing discussions relevant to various genetic, environmental, and immune-related factors. Finally, the applied treatment strategies for curing NMOSD are discussed, exploring the perspectives for developing emergent innovative treatment strategies.

Structural Optimization and Anticancer Activity of Polo-like Kinase 1 (Plk1) Polo-Box Domain (PBD) Inhibitors and Their Prodrugs

Polo-like kinase 1 (Plk1), a mitotic kinase whose activity is widely upregulated in various human cancers, is considered an attractive target for anticancer drug discovery. Aside from the kinase domain, the C-terminal noncatalytic polo-box domain (PBD), which mediates the interaction with the enzyme's binding targets or substrates, has emerged as an alternative target for developing a new class of inhibitors. Various reported small molecule PBD inhibitors exhibit poor cellular efficacy and/or selectivity. Here, we report structure-activity relationship (SAR) studies on triazoloquinazolinone-derived inhibitors, such as 43 (a 1-thioxo-2,4-dihydrothieno[2,3-e][1,2,4]triazolo[4,3-a]pyrimidin-5(1H)-one) that effectively block Plk1, but not Plk2 and Plk3 PBDs, with improved affinity and drug-like properties. The range of prodrug moieties needed for thiol group masking of the active drugs has been expanded to increase cell permeability and mechanism-based cancer cell (L363 and HeLa) death. For example, a 5-thio-1-methyl-4-nitroimidazolyl prodrug 80, derived from 43, showed an improved cellular potency (GI50 4.1 μM). As expected, 80 effectively blocked Plk1 from localizing to centrosomes and kinetochores and consequently induced potent mitotic block and apoptotic cell death. Another prodrug 78 containing 9-fluorophenyl in place of the thiophene-containing heterocycle in 80 also induced a comparable degree of anti-Plk1 PBD effect. However, orally administered 78 was rapidly converted in the bloodstream to parent drug 15, which was shown be relatively stable toward in vivo oxidation due to its 9-fluorophenyl group in comparison to unsubstituted phenyl. Further derivatization of these inhibitors, particularly to improve the systemic prodrug stability, could lead to a new class of therapeutics against Plk1-addicted cancers.

Systemic therapies in vitiligo: a review

Vitiligo is characterized by the development of depigmented macules and patches. Autoimmunity has been established as a factor in disease pathogenesis, leading to utilization of immunosuppressive agents. Topical immunosuppressants are commonly used; however, this treatment modality is often cumbersome and inefficient, as many patients have active disease with extensive body surface area involvement. Prompt and aggressive treatment of vitiligo is important, as this may prevent progression and improve quality of life. To meet these challenges and improve patient outcomes, interest in systemic therapies has grown. Currently, oral therapies are rarely prescribed, likely due to concerns with systemic side effects and unclear efficacy. This article provides a brief overview on the use of systemic agents in treating vitiligo in order to provide additional therapeutic options to clinicians.

Azathioprine hypersensitivity syndrome manifesting as subcutaneous Sweet syndrome and acute pancreatitis

Azathioprine (AZA) is a commonly used immunosuppressive therapy that has been implicated in a number of cutaneous and systemic inflammatory reactions. Initiation of AZA has been associated with a hypersensitivity syndrome manifesting as acute pancreatitis and Sweet syndrome. Subcutaneous Sweet syndrome is a rare variant of Sweet syndrome where the dominant localization of inflammation is within the subcutaneous fat; it is commonly associated with underlying myeloproliferative disease. However, it has not been reported in the literature as a cutaneous manifestation of AZA hypersensitivity syndrome. We present a unique case of acute pancreatitis and biopsy-proven subcutaneous Sweet syndrome following the initiation of AZA with resolution upon discontinuation.

Rationale for off-label treatments use in primary progressive multiple sclerosis: A review of the literature

BACKGROUND

Until recently, few therapeutic options, other than symptomatic treatment, were available for patients with primary progressive multiple sclerosis (PPMS). Ocrelizumab is the only approved treatment in this indication, and only since 2017. However, many patients in France are receiving off-label treatments for PPMS, mainly rituximab, mycophenolate mofetil, methotrexate, cyclophosphamide, and azathioprine.

OBJECTIVE

To evaluate published data concerning the efficacy of these five treatments frequently used as off-label disease-modifying therapies.

METHODS

We reviewed and summarized the studies published in Pubmed since the inception of the database.

RESULTS

Evidence from randomized controlled trials is lacking to support the use of these treatments as disease-modifying therapies in PPMS.

CONCLUSION

The literature lacks dedicated studies to support the off-label use of these disease-modifying therapies in PPMS. However, some limited data are available in the literature suggesting that the use of rituximab and cyclophosphamide could potentially be of some interest in specific subpopulations.

The Use of Azathioprine in Atopic Dermatitis. A Review

Most patients with atopic dermatitis (AD) have a good response to topical treatment. However, some need systemic therapy in order to satisfactorily control the disease. Azathioprine is an accessible drug for patients in many countries, including underdeveloped countries, and therefore it's used by many dermatologists in moderate and severe AD. It is important to have a deep knowledge and understanding about this drug since it is an alternative therapy as a steroid-sparing agent and an affordable one. However, when it comes to systemic therapy for AD, it's not always clear its indications and it is necessary to have a closer follow-up of the patient. In this paper we describe thoroughly it's indications in AD, the mechanism of action of the drug, as well as the interactions, adverse effects, adequate monitoring, and precautions in special population that must be considered when prescribing azathioprine. This review will help dermatologists prescribe it safely to all patients who require it. This article is protected by copyright. All rights reserved.

Pyoderma Gangrenosum: An Updated Literature Review on Established and Emerging Pharmacological Treatments

Pyoderma gangrenosum is a rare inflammatory skin disease classified within the group of neutrophilic dermatoses and clinically characterized by painful, rapidly evolving cutaneous ulcers with undermined, irregular, erythematous-violaceous edges. Pyoderma gangrenosum pathogenesis is complex and involves a profound dysregulation of components of both innate and adaptive immunity in genetically predisposed individuals, with the follicular unit increasingly recognized as the putative initial target. T helper 17/T helper 1-skewed inflammation and exaggerated inflammasome activation lead to a dysregulated neutrophil-dominant milieu with high levels of tumor necrosis factor-α, interleukin (IL)-1β, IL-1α, IL-8, IL-12, IL-15, IL-17, IL-23, and IL-36. Low-evidence studies and a lack of validated diagnostic and response criteria have hindered the discovery and validation of new effective treatments for pyoderma gangrenosum. We review established and emerging treatments for pyoderma gangrenosum. A therapeutic algorithm based on available evidence is also provided. For emerging treatments, we review target molecules and their role in the pathogenesis of pyoderma gangrenosum.

Drug monitoring in systemic lupus erythematosus

Therapeutic drug monitoring (TDM) is not yet accepted by systemic lupus erythematosus (SLE) treatment guidelines. Studies in SLE, however, have proven benefit in three areas: identification of non-adherence or poor adherence; targets for clinical benefit; and ranges of toxicity. This review covers the data on three medications commonly used for SLE, drawing on studies from both the SLE and non-SLE literature.

Immunotargets and Therapy for Prurigo Nodularis

Prurigo nodularis is a chronic inflammatory skin disease consisting of severely pruritic nodules that can be very debilitating for patients. The basis of this skin condition is immunological dysregulation and neural amplification, driven by T-lymphocytes, mast cells, eosinophilic granulocytes, macrophages, and cytokines mediating itchy processes. Further complicating this already taxing diagnosis is the lack of approved treatment and consensus on management; although there are off-label treatments utilized as therapy. Immunomodulators are the cornerstone of treatment for PN, and additional novel therapies targeting key players in the immunological cascade are currently undergoing investigation. In this review, we will highlight targets of the immune cascade and explore current immunomodulating treatments as well as immunotherapies on the horizon for the management of prurigo nodularis.

Effect of NUDT15 polymorphisms on early hematological safety of low-dose azathioprine in Chinese patients with pemphigus vulgaris: A prospective cohort study

Azathioprine (AZA) is the preferred immunosuppressant for treating pemphigus vulgaris (PV), with discontinuation mainly attributed to hematological adverse events (AE). Reportedly, nucleoside diphosphate‐linked moiety X‐type motif 15 (NUDT15) polymorphisms have been strongly associated with thiopurine‐induced leukopenia. To investigate hematological AE of low‐dose AZA based on NUDT15 genotypes among patients with PV, a prospective cohort study was conducted in patients with PV, followed‐up for the first 8 weeks after AZA administration. All patients were divided into wild homozygous and heterozygous NUDT15 groups. Both groups initiated AZA at low dose (50 mg/day) and continued with different dose‐escalating approaches. Bone marrow suppression was considered the principal outcome. Overall, 62 patients with PV were enrolled (48 in the wild homozygous NUDT15 group vs. 14 in the heterozygous NUDT15 group). Except for median maintenance doses of AZA, no statistically significant differences were observed between the two groups in terms of age, sex, white blood cells, neutrophil count, platelet count, hemoglobin level, median final doses of corticosteroids (mg prednisone equivalent), pemphigus disease area index, and anti‐desmoglein 1/3 autoantibodies. In both groups, patients presented similar hematological AE and treatment responses after administration of different low‐dose AZA treatment strategies. Low‐dose AZA based on NUDT15 genotypes can reduce the risk of early hematological AE among patients with PV.

Azathioprine-induced pellagra in a child with autoimmune hepatitis: A case report and literature review

Pellagra is a clinical syndrome resulting from niacin deficiency with variety of manifestations. Azathioprine is among drugs that can lead to such condition. Physicians should be aware as proper management can lead to full resolution.

In vivo assessment of respiratory burst inhibition by xenobiotic exposure using larval zebrafish

Currently, assessment of the potential immunotoxicity of a given agent involves a tiered approach for hazard identification and mechanistic studies, including observational studies, evaluation of immune function, and measurement of susceptibility to infectious and neoplastic diseases. These studies generally use costly low-throughput mammalian models. Zebrafish, however, offer an excellent alternative due to their rapid development, ease of maintenance, and homology to mammalian immune system function and development. Larval zebrafish also are a convenient model to study the innate immune system with no interference from the adaptive immune system. In this study, a respiratory burst assay (RBA) was utilized to measure reactive oxygen species (ROS) production after developmental xenobiotic exposure. Embryos were exposed to non-teratogenic doses of chemicals and at 96 h post-fertilization, the ability to produce ROS was measured. Using the RBA, 12 compounds with varying immune-suppressive properties were screened. Seven compounds neither suppressed nor enhanced the respiratory burst; five reproducibly suppressed global ROS production, but with varying potencies: benzo[a]pyrene, 17β-estradiol, lead acetate, methoxychlor, and phenanthrene. These five compounds have all previously been reported as immunosuppressive in mammalian innate immunity assays. To evaluate whether the suppression of ROS by these compounds was a result of decreased immune cell numbers, flow cytometry with transgenic zebrafish larvae was used to count the numbers of neutrophils and macrophages after chemical exposure. With this assay, benzo[a]pyrene was found to be the only chemical that induced a change in the number of immune cells by increasing macrophage but not neutrophil numbers. Taken together, this work demonstrates the utility of zebrafish larvae as a vertebrate model for identifying compounds that impact innate immune function at non-teratogenic levels and validates measuring ROS production and phagocyte numbers as metrics for monitoring how xenobiotic exposure alters the innate immune system.

Multiple-Molecule Drug Design Based on Systems Biology Approaches and Deep Neural Network to Mitigate Human Skin Aging

Human skin aging is affected by various biological signaling pathways, microenvironment factors and epigenetic regulations. With the increasing demand for cosmetics and pharmaceuticals to prevent or reverse skin aging year by year, designing multiple-molecule drugs for mitigating skin aging is indispensable. In this study, we developed strategies for systems medicine design based on systems biology methods and deep neural networks. We constructed the candidate genomewide genetic and epigenetic network (GWGEN) via big database mining. After doing systems modeling and applying system identification, system order detection and principle network projection methods with real time-profile microarray data, we could obtain core signaling pathways and identify essential biomarkers based on the skin aging molecular progression mechanisms. Afterwards, we trained a deep neural network of drug–target interaction in advance and applied it to predict the potential candidate drugs based on our identified biomarkers. To narrow down the candidate drugs, we designed two filters considering drug regulation ability and drug sensitivity. With the proposed systems medicine design procedure, we not only shed the light on the skin aging molecular progression mechanisms but also suggested two multiple-molecule drugs for mitigating human skin aging from young adulthood to middle age and middle age to old age, respectively.

Azathioprine: its uses in dermatology

This is a narrative review of azathioprine. This medication is immunomodulatory and immunosuppressive, and it has been used widely through different medical specialties to modify disease. It has been proven useful for several dermatoses and it has encountered success when used as an off-label indication for other dermatologic diseases. Its mechanism of action is described thoroughly, as well as precautions for monitoring adequate levels in patients using it. Dermatologists should also be aware of the possible adverse events it may present. In dermatology it can be used in bullous and autoimmune diseases, and in other conditions, including intractable pruritus, atopic dermatitis, photodermatoses, psoriasis, and others. Azathioprine offers an alternative as a steroid-sparing agent and this review helps dermatologists prescribe it safely to all patients who require it.

Is weekly azathioprine pulse effective and safe in dermatological conditions?

Azathioprine, a purine synthesis inhibitor is widely used as an effective immunosuppressant in several immune mediated diseases, usually in a dose of 2 to 2.5 mg/kg per day. The pulse dose of azathioprine is an unique once weekly dosing regimen, which has been used as an alternative to daily dose regimen in some immune mediated dermatologic disorders. In this review, we looked at a specific dosing regimen, "weekly azathioprine pulse" with respect to its efficacy and safety in the treatment of dermatologic diseases. We performed a literature search for studies on azathioprine weekly pulse in dermatology in various scientific databases using keywords "azathioprine-pulse", "dermatology", "weekly azathioprine", and so on. Dosing regimens, indications, efficacy, monitoring, and side effect profile as described in these studies were recorded. Evidence level of the regimens used in various indications was also calculated. We could find six published studies using azathioprine weekly pulse, of which three were randomized comparative clinical trials. Azathioprine pulse was administered in a dose of 300 mg (6 tablets of 50 mg each) every week in all the studies. It has been found to be effective in management of contact dermatitis due to parthenium (IB), chronic plaque psoriasis (IIB), and alopecia areata (IB). Adverse effect profile was found to be almost similar to daily azathioprine. Weekly azathioprine pulse, therefore, appears to be an effective and safe alternative to daily azathioprine in the management of immune mediated disorders in dermatology. Although studies are limited, this regimen seems promising and further studies are warranted.

Neoplasm Risk in Rheumatic Diseases Has No Correlation With Conventional Synthetic Disease-Modifying Anti-rheumatic Drugs Usage-A Population-Based Nested Case-Control Study

Objectives: To investigate whether there is an elevated neoplasm risk in patients with rheumatic diseases treated with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs). Methods: A population-based nested case-control study was performed by retrieving all patients newly diagnosed with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and psoriatic arthritis (PsA) or psoriasis vulgaris (PsO) from the 2000 Longitudinal Health Insurance Database (LHID 2000) in Taiwan. Two hundred and sixty-one patients with neoplasm from 1997 to 2013 were enrolled in this study, and controls were matched in a 1:1 ratio with age, sex, and year of enrollment. Composition of demographic indices, comorbidities, medication usage, and differences in days of prescription of different medications between neoplasm and neoplasm-free (control) groups were compared. Results: Between the control and neoplasm groups, no differences in ratio were observed in the usage of hydroxychloroquine (50.96 vs. 49.04%, p = 0.6616), methotrexate (26.82 vs. 27.59%, p = 0.8441), azathioprine (3.45 vs. 3.07%, p = 0.8052), and cyclophosphamide (1.15 vs. 2.30%, p = 0.3131) from enrollment to index date. Medications within 3 years before the index date in patients that had ≥3 months of comparable duration also showed no difference (hydroxychloroquine: 33.06 vs. 30.25%, p = 0.6404; methotrexate: 20.66 vs. 25.21%, p = 0.4018; azathioprine: 2.48 vs. 2.52%, p = 0.9835; cyclophosphamide: 0.83 vs. 0.84%, p = 0.9906). We also made a subgroup analysis focusing on RA and SLE patients; no difference between control and neoplasm group in both the ratio of usage and days of prescription of hydroxychloroquine, methotrexate, azathioprine, and cyclophosphamide was observed. Conclusion: Neoplasm risk in patients with rheumatic diseases has no correlation with csDMARD usage.

Drug-Induced Neutropenia During Treatment of Non-Neoplastic Dermatologic Diseases: A Review

Idiosyncratic drug-induced neutropenia (DIN) is a rare, potentially fatal adverse reaction. A literature search was performed on Pubmed and Embase, targeting articles indicating neutropenia as a complication during the treatment of non-neoplastic dermatological disorders. In 66 identified articles, the common incriminated drugs included conventional oral immunomodulators, topical cytotoxic agents, antibacterials, antifungals, biologics and targeted synthetic disease-modifying antirheumatic drugs, non-steroidal anti-inflammatory drugs, and retinoids, with dapsone being reported most often. The duration of drug exposure before the diagnosis of neutropenia varied, but mostly ranged from days to weeks. The majority of patients recovered after drug discontinuation and supportive management including antibiotics and granulocyte colony-stimulating factor, but fatal cases were reported. The proposed pathogenesis of DIN consists of direct drug toxicity and immune-mediated reaction. Certain genetic variants, individual variability in enzyme efficiency, and concomitant use of other drugs may increase the risk of DIN. Being familiar with the most commonly implicated agents and risk factors helps early identification and prompt management of this potentially fatal complication.

Discovery, Synthesis, and Scale-up of Efficient Palladium Catalysts Useful for the Modification of Nucleosides and Heteroarenes

Nucleic acid derivatives are imperative biomolecules and are involved in life governing processes. The chemical modification of nucleic acid is a fascinating area for researchers due to the potential activity exhibited as antiviral and antitumor agents. In addition, these molecules are also of interest toward conducting useful biochemical, pharmaceutical, and mutagenic study. For accessing such synthetically useful structures and features, transition-metal catalyzed processes have been proven over the years to be an excellent tool for carrying out the various transformations with ease and under mild reaction conditions. Amidst various transition-metal catalyzed processes available for nucleoside modification, Pd-catalyzed cross-coupling reactions have proven to be perhaps the most efficient, successful, and broadly applicable reactions in both academia and industry. Pd-catalyzed C-C and C-heteroatom bond forming reactions have been widely used for the modification of the heterocyclic moiety in the nucleosides, although a single catalyst system that could address all the different requirements for nucleoside modifications isvery rare or non-existent. With this in mind, we present herein a review showcasing the recent developments and improvements from our research groups toward the development of Pd-catalyzed strategies including drug synthesis using a single efficient catalyst system for the modification of nucleosides and other heterocycles. The review also highlights the improvement in conditions or the yield of various bio-active nucleosides or commercial drugs possessing the nucleoside structural core. Scale ups wherever performed (up to 100 g) of molecules of commercial importance have also been disclosed.

Safety of the current drug treatments for vitiligo

Introduction: Vitiligo is an acquired depigmenting skin disorder adversely affecting the patient's quality of life. Despite the presence of several treatment modalities, ranging from medical to physical to surgical options, none is curative. Each modality has its own drawbacks and side effects. Thus, the treatment modality needs to be tailored for each individual patient taking into consideration the disease characteristics and also its efficacy and safety to obtain a favorable risk-benefit ratio.Areas covered: This review highlights the different treatment modalities utilized in vitiligo up until 4 November 2019 along with their adverse effects and contraindications, if any.Expert opinion: All the medications have their own adverse effects and contraindications. We have included the most commonly used topical corticosteroids, which may result in striae, cutaneous atrophy, and tachyphylaxis, to the recently introduced biologics, which may induce hypersensitivity reactions, systemic toxicities, and even malignancies. However, more long-term studies are needed to assess the safety of these medications, especially the newer ones, to provide a safe and effective treatment for this disorder.

Safety considerations when using drugs to treat pruritus

Introduction: Treatment for chronic pruritus ranges from use of topical formulations to newer biologic agents. Targeting treatment to the underlying etiology is key in reducing the burden of disease while avoiding systemic or adverse effects.Areas covered: This review details the effective medical treatments used in various etiologies of chronic itch with a focus on the potential adverse effects and safety data available for each.Expert opinion: New drug developments in the areas of neural signaling and immune targeting show great promise for the future of chronic itch treatment. These new therapies broaden the available treatment options but also pose new considerations for safety and adverse effects.

Solubility of solid intermediate of pharmaceutical compounds in pure organic solvents using semi-empirical models

A new semi-theoretical equation is suggested for correlation of solid-liquid solubility data with temperature. The (solid + liquid) equilibrium for Terephthaldialdehyde, 4-Nitro-o-phennylenediamine, 2,4-dihydro- 5-methyl-2-(4-methylphenyl)-3H-pyrazol-3-one (also named 1-(p-tolyl)-3-methyl-5pyrazolone (PTMP)), 2-Amino-5-methylthiazole and 5-chloro-1-methyl-4-nitroimidazole in 18 solvents is correlated with semi-empirical models at temperatures T = 273.15-318.15 K under a pressure of 101.2 kPa. Moreover, a modified Apelblat model, λh model, Wilson model, NRTL model, new flexible equation as Akbari, Dideban and Farhang model (ADF) and for first time the modified Scatchard-Hildebrand equation were utilized to calculate the experiment values. The performance of both ADF and modified Scatchard-Hildebrand equation have been checked by calculating the solubility data with the AARD% of 1.3808% (for 775 data points) and 0.65% (for 100 data points), respectively. The Wilson model is applied to estimate the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient (ln γ₁^∞) and reduced excess enthalpy (H₁^{E, ∞}) at infinitesimal concentration were calculated.

Predictive Value of NUDT15 Variants on Neutropenia Among Han Chinese Patients with Dermatologic Diseases: A Single-Center Observational Study

Introduction

Azathioprine is a synthetic purine analogue derived from 6-mercaptopurine which acts by disrupting nucleic acid synthesis and interfering with T cell activation. It is effective in dermatology diseases related to the immune system. However, its side effects, including severe neutropenia, kept patients from using it. Mutations in thiopurine methyltransferase (TPMT) and inosine triphosphate pyrophosphohydrolase (ITPA) genes account for the major genetic polymorphism markers for azathioprine adverse risk factors in Caucasians, but not in Asians. The predictive value of the nucleoside diphosphate-linked moiety X motif 15 gene (NUDT15) has been studied in various diseases among different populations. The aim of our study was to determine the contribution of NUDT15 mutations in azathioprine-induced neutropenia in Han Chinese patients with dermatologic diseases.

Methods

The study enrolled all consecutive patients, older than 13 years old, with dermatological diseases currently treated orally with azathioprine in our clinic. Samples were also collected from patients with documented leukopenia in our prior study that examined the association between TPMT, ITPA, and neutropenia after informed reconsent. Complete blood count, differential count, and hepatic and renal function were checked regularly. The DNA samples for NUDT15 genotype were obtained from the patients.

Results

In total, we enrolled 56 patients (39 male, 17 female). The NUDT15 genotypes are mostly C/C (N = 36, 64.29%). Heterozygous variant (C/T) accounts for 30.36% (N = 17) and homozygous variant (T/T) accounts for 5.36% (N = 3). Among these patients, 15 patients (26.79%) developed neutropenia, including all three patients carry homozygous variant (T/T). The age-, sex-, and dose-adjusted risk of heterozygous variant compared to wild type is 9.383 (95% CI 1.32–66.96).

Conclusions

Pretreatment screening of NUDT15 might reduce the chance of azathioprine-induced neutropenia in Han Chinese patients with dermatologic diseases.

Proteases in Pemphigoid Diseases

Pemphigoid diseases are a subgroup of autoimmune skin diseases characterized by widespread tense blisters. Standard of care typically involves immunosuppressive treatments, which may be insufficient and are often associated with significant adverse events. As such, a deeper understanding of the pathomechanism(s) of pemphigoid diseases is necessary in order to identify improved therapeutic approaches. A major initiator of pemphigoid diseases is the accumulation of autoantibodies against proteins at the dermal-epidermal junction (DEJ), followed by protease activation at the lesion. The contribution of proteases to pemphigoid disease pathogenesis has been investigated using a combination of in vitro and in vivo models. These studies suggest proteolytic degradation of anchoring proteins proximal to the DEJ is crucial for dermal-epidermal separation and blister formation. In addition, proteases can also augment inflammation, expose autoantigenic cryptic epitopes, and/or provoke autoantigen spreading, which are all important in pemphigoid disease pathology. The present review summarizes and critically evaluates the current understanding with respect to the role of proteases in pemphigoid diseases.

Pharmacogenomics in dermatology: tools for understanding gene-drug associations

Pharmacogenomics aims to associate human genetic variability with differences in drug phenotypes in order to tailor drug treatment to individual patients. The massive amount of genetic data generated from large cohorts of patients with variable drug phenotypes have led to advances in this field. Understanding the application of pharmacogenomics in dermatology could inform clinical practice and provide insight for future research. The Pharmacogenomics Knowledge Base and the Clinical Pharmacogenetics Implementation Consortium are among the resources to help clinicians and researchers navigate the many gene-drug associations that have already been discovered. The implementation of clinical pharmacogenomics within health care systems remains an area of ongoing development. This review provides an introduction to the field of pharmacogenomics and to current pharmacogenomics resources using examples of gene-drug associations relevant to the field of dermatology.

Hailey-Hailey disease: the role of azathioprine an immunomodulator

Hailey-Hailey disease (HHD) is a rare autosomal dominant hereditary blistering and erosions disorder affecting the intertriginous regions of the body. There is still no treatment protocol for this disease thus clinicians are highly advised to draw up individualized treatment plan. In this case report, we discuss a case of HHD in a 58-year-old Chinese man who was successfully treated with azathioprine in Hubei province.

Azathioprine-induced pellagra in neuromyelitis optica: A case report and review of literature

Neuromyelitis optica (NMO), also known as Devic's disease, is a classical autoimmune disorder of the central nervous system (CNS). The relapsing-remitting disease course contributes to application of a variety of immunosuppressants to prevent further relapses after high-dose methylprednisolone pulse therapy for acute attacks. Azathioprine is one of the most widely used immunosuppressive drugs during the remission stage of NMO due to its good efficacy and favorable side-effect profile. Even if, enough attention should be paid to some rare but devastating adverse events, such as pellagra. Herein, we reported that a well-nourished patient experienced serious pellagra while receiving oral azathioprine for treating her NMO. Moreover, literature on azathioprine-induced pellagra was reviewed to raise concerns regarding patient safety.

Erythema Nodosum Leprosum: Update and challenges on the treatment of a neglected condition

Erythema Nodosum Leprosum (ENL) occurs due to the immunological complication of multibacillary leprosy and is characterized by painful nodules and systemic compromising. It is usually recurrent and/or chronic and has both physical and economic impact on the patient, being a very important cause of disability. In addition, ENL is a major health problem in countries where leprosy is endemic. Therefore, adequate control of this condition is important. The management of ENL aims to control acute inflammation and neuritis and prevent the onset of new episodes. However, all currently available treatment modalities have one or two drawbacks and are not effective for all patients. Corticosteroid is the anti-inflammatory of choice in ENL but may cause dependence, especially for chronic patients. Thalidomide has a rapid action but its use is limited due the teratogenicity and neurotoxicity. Clofazimine and pentoxifylline have slow action and have important adverse effects. Finally, there is no pattern or guidelines for treating these patients, becoming more difficult to evaluate and to control this condition. This review aims to show the main drugs used in the treatment of ENL and the challenges in the management of the reaction.

Multidirectional Efficacy of Biologically Active Nitro Compounds Included in Medicines

The current concept in searching for new bioactive products, including mainly original active substances with potential application in pharmacy and medicine, is based on compounds with a previously determined structure, well-known properties, and biological activity profile. Nowadays, many commonly used drugs originated from natural sources. Moreover, some natural materials have become the source of leading structures for processing further chemical modifications. Many organic compounds with great therapeutic significance have the nitro group in their structure. Very often, nitro compounds are active substances in many well-known preparations belonging to different groups of medicines that are classified according to their pharmacological potencies. Moreover, the nitro group is part of the chemical structure of veterinary drugs. In this review, we describe many bioactive substances with the nitro group, divided into ten categories, including substances with exciting activity and that are currently undergoing clinical trials.

Purine Synthesis Inhibitors, 6-thioguanine and Azathioprine: Forgotten Treatment Options in Psoriasis and Psoriatic Arthritis

Background

The thiopurine drugs azathioprine and 6-thioguanine have been shown to induce significant clinical improvement in patients with moderate to severe psoriasis and/or psoriatic arthritis.

Objective

The aim of this paper is to present a comprehensive review of the available literature concerning the off-label role of thiopurine drugs in the treatment of psoriasis and psoriatic arthritis.

Methods

Studies published with English abstracts between 1960 and 2008 identified in MEDLINE and PubMed with the keywords purine synthesis inhibitors, thiopurine, 6-thioguanine, azathioprine, psoriasis and psoriatic arthritis were reviewed.

Results

Although 6-thioguanine and azathioprine have shown significant efficacy, their side effect profiles have discouraged their use for moderate to severe psoriasis.

Conclusion

For treatment of psoriasis and psoriatic arthritis, purine synthesis inhibitors should not be forgotten. They represent an entirely different option and provide an alternative therapy, especially for difficult cases.

The associations of thiopurines with male fertility and paternally exposed offspring: a systematic review and meta-analysis

BACKGROUND

Thiopurines are widely used immunosuppressive agents. In high dosages, they inhibit the purine synthesis and are considered to be possibly harmful to spermatogenesis, and subsequently to men's fertility and their offspring. However, the clear association between thiopurine exposure and male fertility and reproduction safety, if any, is still poorly understood.

OBJECTIVE AND RATIONALE

The aim of this review was to systematically summarize and meta-analyse the available data, derived from animal and human studies, regarding the influence of thiopurine exposure on fertility and conception safety in men and their offspring.

SEARCH METHODS

A systematic literature search of the MEDLINE and EMBASE databases was performed using a combination of relevant terms related to 'thiopurines', 'fertility', 'conception', 'reproduction', 'semen quality' and 'birth outcome', combined with 'male', 'men', 'father' and 'paternal'. The search was not restricted exclusively to human subjects, neither to a type of disease or condition, to gather all available studies with regards to this topic. All published articles on thiopurines and male fertility, written in English and published until May 2017, were screened for eligibility. The GRADE guidelines were used to assess the quality of evidence of the included articles.

OUTCOMES

A total of 28 studies (including 14 observational studies in humans) were included in this review and six of these were included in the meta-analysis. In various rodents, thiopurines adversely affected the germ cells (in administered doses of 2 to 20 times the human equivalent dose). In human studies, thiopurine therapy was not evidently associated with impaired testicular function or semen quality in 83 men with a variety of underlying diseases. In total, 53 out of 975 offspring with congenital anomalies (5.4%, the background prevalence is 3%), possibly as a result of paternal thiopurine exposure, were described in all studies together. The risk of congenital anomalies was not significantly increased when compared with offspring without paternal thiopurine exposure (4.7%) (pooled odds ratio 1.32, 95% confidence interval 0.75, 2.34).

WIDER IMPLICATIONS

Thiopurines have spermatotoxic effects in rodents. In humans, overall data are limited and derived from underpowered studies, and therefore not conclusive with regards to the possible effects of thiopurines on spermatogenesis or paternally exposed offspring. Larger, epidemiological trials evaluating the safety of thiopurines to men's fertility and their offspring are mandatory to adequately counsel thiopurine treated men who wish to conceive.

Cutaneous Toxicities From Transplantation-Related Medications

Despite the abundance of information on cutaneous malignancies associated with solid organ transplantation in the transplant literature, there is limited information regarding nonmalignant skin changes after transplantation. There are numerous skin toxicities secondary to immunosuppressive and other transplant-related medications that can vary in presentation, severity, and prognosis. To limit associated morbidity and mortality, solid organ transplant recipient care providers should effectively identify and manage cutaneous manifestations secondary to drug toxicity. Toxicities from the following transplant-related medications will be discussed: antithymocyte globulins, systemic steroids, cyclosporine, tacrolimus, azathioprine, mycophenolate mofetil, mammalian target of rapamycin inhibitors sirolimus and everolimus, basiliximab and daclizumab, belatacept, and voriconazole.

Thiopurine S-Methyltransferase Polymorphisms in Korean Dermatologic Patients

Background

Thiopurine S-methyltransferase (TPMT) is an important enzyme in the metabolism of thiopurines including azathioprine (AZA), 6-mercaptopurine, and 6-thioguanine. TPMT genotyping is widely used for screening of AZA-related toxicity during routine clinical practice in Korea. However, the data of TPMT genotypes and its AZA-related toxicity have not been studied in the field of dermatology.

Objective

The aim of this study was to evaluate the genetic basis of TPMT polymorphism in Korean dermatologic patients and subsequently to investigate the relationship between mutant TPMT and adverse responses to AZA treatment.

Methods

This study was retrospective, single-center study. One hundred forty-nine Korean dermatologic patients who underwent TPMT screening test were included. Each patient's medical records, the result of TPMT screening test, dose and treatment period of AZA, and side effects, were reviewed. Laboratory tests were assessed at each visit in order to monitor adverse drug reactions. Leukopenia grading was used in accordance with the common terminology criteria for adverse events (CTCAE) ver. 4.03.

Results

Behçet's disease was the leading disorder among the patients. The frequency of TPMT mutation was 4.0% (6/149) among the participants in this study. Four of the six patients with genetic alterations were treated with a low-dose AZA regimen, but no AZA-related adverse events were observed.

Conclusion

Our results suggest that 1) TPMT polymorphisms in Korean dermatologic patients are similar to those previously reported in Asian patients with the most common mutant allele being TPMT^*3C and 2) AZA can be used in the patients with these polymorphisms under a careful dosing regimen.

Practical Management of Immunosuppressants in Dermatology

The treatment of inflammatory and autoimmune diseases is challenging because of their frequency and complexity. Treatment of these diseases is based on the suppression of the patient's immune system using corticosteroids, corticosteroid-sparing immunosuppressive agents, and biologic drugs, making an understanding of the management of immunosuppressive therapy essential. Before an immunosuppressive agent is prescribed, a study must be carried out to identify contraindications, detect latent infections, and determine the most appropriate dose. During treatment, regular monitoring is required to detect adverse effects. The clinician must be familiar with the time lag between start of treatment and onset of the immunosuppressive effect as well as the maximum recommended duration of treatment and cumulative dose for each drug. As dermatologists we are accustomed to using these immunosuppressive agents, but we should have a good knowledge of the guidelines for their use and the monitoring required in each case if we are to reduce variability and avoid potentially serious adverse effects.

Pharmacological Approaches to the Management of Secondary Progressive Multiple Sclerosis

It is well recognised that the majority of the impact of multiple sclerosis (MS), both personal and societal, arises in the progressive phase where disability accumulates inexorably. As such, progressive MS (PMS) has been the target of pharmacological therapies for many years. However, there are no current licensed treatments for PMS. This stands in marked contrast to relapsing remitting MS (RRMS) where trials have resulted in numerous licensed therapies. PMS has proven to be a more difficult challenge compared to RRMS and this review focuses on secondary progressive MS (SPMS), where relapses occur before the onset of gradual, irreversible disability, and not primary progressive MS where disability accumulation occurs without prior relapses. Although there are similarities between the two forms, in both cases pinpointing when PMS starts is difficult in a condition in which disability can vary from day to day. There is also an overlap between the pathology of relapsing and progressive MS and this has contributed to the lack of well-defined outcomes, both surrogates and clinically relevant outcomes in PMS. In this review, we used the search term 'randomised controlled clinical drug trials in secondary progressive MS' in publications since 1988 together with recently completed trials where results were available. We found 34 trials involving 21 different molecules, of which 38% were successful in reaching their primary outcome. In general, the trials were well designed (e.g. double blind) with sample sizes ranging from 35 to 1949 subjects. The majority were parallel group, but there were also multi-arm and multidose trials as well as the more recent use of adaptive designs. The disability outcome most commonly used was the Expanded Disability Status Scale (EDSS) in all phases, but also magnetic resonance imaging (MRI)-measured brain atrophy has been utilised as a surrogate endpoint in phase II studies. The majority of the treatments tested in SPMS over the years were initially successful in RRMS. This has a number of implications in terms of targeting SPMS, but principally implies that the optimal strategy to target SPMS is to utilise the prodrome of relapses to initiate a therapy that will aim to both prevent progression and slow its accumulation. This approach is in agreement with the early targeting of MS but requires treatments that are both effective and safe if it is to be used before disability is a major problem. Recent successes will hopefully result in the first licensed therapy for PMS and enable us to test this approach.