Second-generation antihistamines: a comparative review

Photoredox-Catalyzed Decarboxylative Cross-Coupling Reaction to Synthesis Unsymmetrical Diarylmethanes

The photoredox-catalyzed decarboxylative cross-coupling reaction of aryl acetic acids and aryl nitriles has been achieved under an argon atmosphere in high yields. This method provides a fast way to obtain prevalent aryl acetic acids from an abundant natural source. A tentative radical mechanism has been proposed.

Incorporation of Loratadine-Cyclodextrin Complexes in Oral Thin Films for Rapid Drug Delivery

Rapidly dissolving polymer thin films, or oral thin films (OTFs), have recently emerged as an improved oral drug delivery vehicle with its ability to bypass liver first pass metabolism, longer shelf-life, and simpler transport and distribution requirements, compared to traditional tablets and liquid formulations. Loratadine (LOR), an antihistamine commonly used to treat allergic rhinitis, undergoes liver first pass metabolism and is a prime candidate for incorporation within an OTF. However, loratadine is a BCS II drug with low aqueous solubility. Herein, the solubility of loratadine was improved by complexation with methyl β-cyclodextrin (MBCD) by co-evaporation of 2:1, 1:1, and 1:2 LOR:MBCD ratios and incorporation into a pullulan-based OTF at 4 wt% by solvent casting at 50 °C for 30 - 35 min. A therapeutically relevant 10 mg LOR dose could be prepared in a 3 cm by 3 cm OTF. The feasibility of complexation was observed with a Bs-type phase solubility diagram, and complexation itself was confirmed via differential scanning calorimetry (DSC) by disappearance of the LOR melting peak, Fourier-transform infrared spectroscopy (FTIR) by shifting of the C=O peak, via 1H NMR spectroscopy by downfield shifting and change in peak multiplicity of the LOR aromatic protons, and via diffusion-ordered spectroscopy by a decrease in the diffusion coefficient of LOR:MBCD complex. LOR:MBCD could be incorporated homogeneously throughout an OTF, and LOR:MBCD OTFs exhibited reasonable mechanical strength and endured 12 ± 3 folds before breaking. LOR:MBCD OTFs disintegrated within 38 ± 10 s. The cumulative in vitro release of LOR:MBCD OTFs peaked at 80 % within 3-4 min of dissolution, and LOR in LOR:MBCD OTFs exhibited permeability across a 0.22 μm nitrocellulose membrane, demonstrating its applicability as a rapid drug delivery vehicle.

Calcium and Neural Stem Cell Proliferation

Intracellular calcium plays a pivotal role in central nervous system (CNS) development by regulating various processes such as cell proliferation, migration, differentiation, and maturation. However, understanding the involvement of calcium (Ca2+) in these processes during CNS development is challenging due to the dynamic nature of this cation and the evolving cell populations during development. While Ca2+ transient patterns have been observed in specific cell processes and molecules responsible for Ca2+ homeostasis have been identified in excitable and non-excitable cells, further research into Ca2+ dynamics and the underlying mechanisms in neural stem cells (NSCs) is required. This review focuses on molecules involved in Ca2+ entrance expressed in NSCs in vivo and in vitro, which are crucial for Ca2+ dynamics and signaling. It also discusses how these molecules might play a key role in balancing cell proliferation for self-renewal or promoting differentiation. These processes are finely regulated in a time-dependent manner throughout brain development, influenced by extrinsic and intrinsic factors that directly or indirectly modulate Ca2+ dynamics. Furthermore, this review addresses the potential implications of understanding Ca2+ dynamics in NSCs for treating neurological disorders. Despite significant progress in this field, unraveling the elements contributing to Ca2+ intracellular dynamics in cell proliferation remains a challenging puzzle that requires further investigation.

Solubility and Physical Stability Enhancement of Loratadine by Preparation of Co-Amorphous Solid Dispersion with Chlorpheniramine and Polyvinylpyrrolidone

Loratadine (LRD), a non-sedating and slow-acting antihistamine, is often given in combination with short-onset chlorpheniramine maleate (CPM) to increase efficacy. However, LRD has poor water solubility resulting in low bioavailability. The aim of this study was to improve LRD solubility by preparing co-amorphous LRD-CPM. However, the obtained co-amorphous LRD-CPM recrystallized rapidly, and the solubility of LRD returned to a poor state again. Therefore, co-amorphous LRD-CPM solid dispersions using polyvinylpyrrolidone (PVP) as a carrier were prepared. The obtained solid dispersions were characterized using X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FT-IR). The solubility, dissolution, and mechanism of drug release from the LRD-CPM/PVP co-amorphous solid dispersions were studied and compared with those of intact LRD, LRD/PVP solid dispersions, and co-amorphous LRD-CPM mixtures. The results from XRPD and DSC confirmed the amorphous form of LRD in the co-amorphous solid dispersions. The FTIR results indicated that there was no intermolecular interaction between LRD, CPM, and PVP. In conclusion, the obtained LRD-CPM/PVP co-amorphous solid dispersions can successfully increase the water solubility and dissolution of LRD and extend the amorphous state of LRD without recrystallization.

2023 Guidelines on the Diagnosis and Treatment of Insomnia in Adults - Brazilian Sleep Association

Chronic insomnia disorder (simplified in this document as insomnia) is an increasingly common clinical condition in society and a frequent complaint at the offices of different areas of health practice (particularly Medicine and Psychology). This scenario has been accompanied by a significant evolution in treatment, as well as challenges in approaching patients in an appropriately way. This clinical guideline, coordinated by the Brazilian Sleep Association and the Brazilian Association of Sleep Medicine and counting on the active participation of various specialists in the area, encompasses an update on the diagnosis and treatment of insomnia in adults. To this end, it followed a structured methodology. Topics of interest related to diagnosis were written based on theoretical framework, evidence in the literature, and professional experience. As for the topics related to the treatment of insomnia, a series of questions were developed based on the PICO acronym (P - Patient, problem, or population; I - Intervention; C - Comparison, control, or comparator; O - Outcome). The work groups defined the eligible options within each of these parameters. Regarding pharmacological interventions, only the ones currently available in Brazil or possibly becoming available in the upcoming years were considered eligible. Systematic reviews were conducted to help prepare the texts and define the level of evidence for each intervention. The final result is an objective and practical document providing recommendations with the best scientific support available to professionals involved in the management of insomnia.

Wheatgrass-and-Aronia-Mixed Extract Suppresses Immunoglobulin E-Mediated Allergic Reactions In Vitro and In Vivo

Mast cells are an important component of immune responses. Immunoglobulin (Ig) E-sensitized mast cells release substances within minutes of allergen exposure, triggering allergic responses. Until now, numerous pharmacological effects of wheatgrass and aronia have been verified, but the effects of wheatgrass and aronia (TAAR)-mixed extract on allergic reactions have not been identified. Therefore, the aim of this study was to demonstrate the anti-allergic effect of TAAR extract on mast cell activation and cutaneous anaphylaxis. In this study, we investigated the anti-allergic effects and related mechanisms of TAAR extract in IgE-activated mast cells in vitro. We also assessed the ameliorating effect of TAAR extract on IgE-mediated passive cutaneous anaphylaxis mice in vivo. The TAAR extract significantly reduced the expression of β-hexosaminidase, histamine, and pro-inflammatory cytokines, which are mediators related to mast cell degranulation, via the regulation of various signaling pathways. The TAAR extract also regulated oxidative-stress-related factors through the Nrf2 signaling pathway. Additionally, treatment of TAAR extract to the passive cutaneous anaphylaxis mouse model improved ear thickness and local ear pigmentation. Taken together, our results suggest that TAAR extract is a potential candidate natural product to treat overall IgE-mediated allergic inflammation and oxidative-stress-related diseases by suppressing mast cell activity.

Sleep disturbances in autism spectrum disorder: Animal models, neural mechanisms, and therapeutics

Sleep is crucial for brain development. Sleep disturbances are prevalent in children with autism spectrum disorder (ASD). Strikingly, these sleep problems are positively correlated with the severity of ASD core symptoms such as deficits in social skills and stereotypic behavior, indicating that sleep problems and the behavioral characteristics of ASD may be related. In this review, we will discuss sleep disturbances in children with ASD and highlight mouse models to study sleep disturbances and behavioral phenotypes in ASD. In addition, we will review neuromodulators controlling sleep and wakefulness and how these neuromodulatory systems are disrupted in animal models and patients with ASD. Lastly, we will address how the therapeutic interventions for patients with ASD improve various aspects of sleep. Together, gaining mechanistic insights into the neural mechanisms underlying sleep disturbances in children with ASD will help us to develop better therapeutic interventions.

Drug delivery targets and strategies to address mast cell diseases

INTRODUCTION

Current and developing mast cell therapeutics are reliant on small molecule drugs and biologics, but few are truly selective for mast cells. Most have cellular and disease-specific limitations that require innovation to overcome longstanding challenges to selectively targeting and modulating mast cell behavior. This review is designed to serve as a frame of reference for new approaches that utilize nanotechnology or combine different drugs to increase mast cell selectivity and therapeutic efficacy.

AREAS COVERED

Mast cell diseases include allergy and related conditions as well as malignancies. Here, we discuss the targets of existing and developing therapies used to treat these disease pathologies, classifying them into cell surface, intracellular, and extracellular categories. For each target discussed, we discuss drugs that are either the current standard of care, under development, or have indications for potential use. Finally, we discuss how novel technologies and tools can be used to take existing therapeutics to a new level of selectivity and potency against mast cells.

EXPERT OPINION

There are many broadly and very few selectively targeted therapeutics for mast cells in allergy and malignant disease. Combining existing targeting strategies with technology like nanoparticles will provide novel platforms to treat mast cell disease more selectively.

Topical Formulation of Nano Spray-Dried Levocetirizine Dihydrochloride against Allergic Edema

Levocetirizine dihydrochloride active ingredient was microencapsulated using nano spray-drying technology for preparing microparticles containing topical gel against edema. Hydroxyl propyl methyl cellulose (HPMC) was used as a carrier polymer during spray drying. The active ingredient content of the nano spray-dried products was 52.81% (w/w) and 51.33% (w/w) for ex vivo and in vivo experiments, respectively, and the average particle size was 2.6 µm. X-ray diffraction analysis indicated an amorphous state of the active ingredient embedded in the amorphous matrix of the polymer. Dermal oil gels composed of Miglyol 812 gelated by Dermofeel viscolid included 5% (w/w) (for ex vivo) and 10% (w/w) (for in vivo) active ingredient without or with 0.05% (w/w) menthol penetration enhancer. Qualitative ex vivo penetration studies using a confocal Raman microscopic correlation mapping were executed on human abdominal skin. The results showed that the active ingredient was enriched in the epidermis and upper dermis layer of the skin using oleogel loaded with the nano spray-dried drug-HPMC composite. Menthol addition to the oleogel resulted in the concentration of levocetirizine in the dermis. In vivo tests were performed on a mouse model of croton oil-induced ear edema. Negative control and Fenistil-treated groups were compared using the prepared oil gels with and without menthol. Without penetration enhancer, 20 µL of our oil gel loaded with nano spray-dried levocetirizine dihydrochloride composite showed similar effectiveness to the same volume of Fenistil gel, while 5 µL menthol containing sample was sufficient to eliminate the skin irritation similarly to 20 µL Fenistil.

Pharmacodynamic model of slow reversible binding and its applications in pharmacokinetic/pharmacodynamic modeling: review and tutorial

Therapeutic responses of most drugs are initiated by the rate and degree of binding to their receptors or targets. The law of mass action describes the rate of drug-receptor complex association (k_on) and dissociation (k_off) where the ratio k_off/k_on is the equilibrium dissociation constant (K_d). Drugs with slow reversible binding (SRB) often demonstrate delayed onset and prolonged pharmacodynamic effects. This report reviews evidence for drugs with SRB features, describes previous pharmacokinetic/pharmacodynamic (PK/PD) modeling efforts of several such drugs, provides a tutorial on the mathematics and properties of SRB models, demonstrates applications of SRB models to additional compounds, and compares PK/PD fittings of SRB with other mechanistic models. We identified and summarized 52 drugs with in vitro-confirmed SRB from a PubMed literature search. Simulations with a SRB model and observed PK/PD profiles showed delayed and prolonged responses and that increasing doses/k_on or decreasing k_off led to greater expected maximum effects and a longer duration of effects. Recession slopes for return of responses to baseline after single doses were nearly linear with an inflection point that approaches a limiting value at larger doses. The SRB model newly captured literature data for the antihypertensive effects of candesartan and antiallergic effects of noberastine. Their PD profiles could also be fitted with indirect response and biophase models with minimal differences. The applicability of SRB models is probably commonplace, but underappreciated, owing to the need for in vitro confirmation of binding kinetics and the similarity of PK/PD profiles to models with other mechanistic determinants.

Combinational benefit of antihistamines and remdesivir for reducing SARS-CoV-2 replication and alleviating inflammation-induced lung injury in mice

COVID-19 is an immune-mediated inflammatory disease caused by SARS-CoV-2 infection, the combination of anti-inflammatory and antiviral therapy is predicted to provide clinical benefits. We recently demonstrated that mast cells (MCs) are an essential mediator of SARS-CoV-2-initiated hyperinflammation. We also showed that spike protein-induced MC degranulation initiates alveolar epithelial inflammation for barrier disruption and suggested an off-label use of antihistamines as MC stabilizers to block degranulation and consequently suppress inflammation and prevent lung injury. In this study, we emphasized the essential role of MCs in SARS-CoV-2-induced lung lesions in vivo, and demonstrated the benefits of co-administration of antihistamines and antiviral drug remdesivir in SARS-CoV-2-infected mice. Specifically, SARS-CoV-2 spike protein-induced MC degranulation resulted in alveolar-capillary injury, while pretreatment of pulmonary microvascular endothelial cells with antihistamines prevented adhesion junction disruption; predictably, the combination of antiviral drug remdesivir with the antihistamine loratadine, a histamine receptor 1 (HR1) antagonist, dampened viral replication and inflammation, thereby greatly reducing lung injury. Our findings emphasize the crucial role of MCs in SARS-CoV-2-induced inflammation and lung injury and provide a feasible combination antiviral and anti-inflammatory therapy for COVID-19 treatment.

Indoor Pollen Concentrations of Mountain Cedar (Juniperus ashei) during Rainy Episodes in Austin, Texas

Standard pollen monitoring programs evaluate outdoor pollen concentrations; however, information on indoor pollen is crucial for human wellbeing as people spend most of the day in indoor environments. In this study, we investigated the differences in indoor mountain cedar pollen loads between rooms of different uses and with different ventilation at The University of Texas in Austin and focused on the effect of rainy episodes on indoor/outdoor ratios of pollen concentrations. Pollen were sampled outdoors and indoors, specifically in seven rooms and in two thermal labs with controlled ventilation, during the daytime on 6 days in 2015. We calculated daily pollen concentrations, campaign pollen integrals (CPIn, the sum of all daily pollen concentrations) and ratios between indoor and outdoor concentrations (I/O ratio). Pollen concentrations differed substantially based on features related to room use and ventilation: Whereas the highest CPIn was observed in a room characterized by a frequently opened window and door, the smallest CPIn was related to a storeroom without any windows and no forced ventilation. Our results showed that rainy episodes were linked to a higher mean I/O ratio (0.98; non-rainy episodes: 0.05). This suggests that pollen accumulated indoors and reached higher levels than outdoors. Low ratios seem to signal a low level of risk for allergic people when staying inside. However, under very high outdoor pollen concentrations, small ratios can still be associated with high indoor pollen levels. In turn, high I/O ratios are not necessarily related to a (very) high indoor exposure. Therefore, I/O ratios should be considered along with pollen concentration values for a proper risk assessment. Exposure may be higher in indoor environments during prevailing precipitation events and at the end of the pollen season of a specific species. Standardized indoor environments (e.g., thermal labs) should be included in pollen monitoring programs.

New Horizons: Is Obesity a Disorder of Neurotransmission?

Obesity is a disease of the nervous system. While some will view this statement as provocative, others will take it as obvious. Whatever our side is, the pharmacology tells us that targeting the nervous system works for promoting weight loss. It works, but at what cost? Is the nervous system a safe target for sustainable treatment of obesity? What have we learned-and unlearned-about the central control of energy balance in the last few years? Herein we provide a thought-provoking exploration of obesity as a disorder of neurotransmission. We discuss the state of knowledge on the brain pathways regulating energy homeostasis that are commonly targeted in anti-obesity therapy and explore how medications affecting neurotransmission such as atypical antipsychotics, antidepressants, and antihistamines relate to body weight. Our goal is to provide the endocrine community with a conceptual framework that will help expending our understanding of the pathophysiology of obesity, a disease of the nervous system.

Toxicological screening and evaluation of anti-allergic and anti-hyperglycemic potential of Sonneratia caseolaris (L.) Engl. fruits

Background

Sonneratia caseolaris (L.) Engl. (S. caseolaris) belonging to the Sonneratiaceae family is commonly known as Ora. It is traditionally used as an astringent, antiseptic, to treat sprains, swellings, cough and in arresting hemorrhage. The ethanolic extract of S. caseolaris (L.) Engl. fruits was investigated in the present study for its toxicity as well as anti-allergic and anti-hyperglycemic potentials.

Methods

Major phenolic compounds were identified and quantified by HPLC. Behavioral change, body weight, mortality and different blood parameters were measured to assess the toxicological effect of the extract. Anti-allergic activity was evaluated using TDI-induced allergic model mice. Oral glucose tolerance test (OGTT) and STZ-induced diabetic mice were used to evaluate the anti-hyperglycemic activity.

Results

Crude extract contained ellagic acid, vanillic acid and myrecitin (27.41, 3.06 and 7.93 mg per 100 g dry extract respectively). No major toxicity was observed in both acute and sub-acute toxicity study. Oral administration of the extract significantly ameliorated TDI-induced allergic symptoms like sneezing, scratching, swelling, redness and watery rhinorrhoea in the experimental mice. The extracts also reduced the total and differential count of leukocytes in the blood. The extract treated mice showed significant reduction in blood glucose, SGOT, SGPT, cholesterol, triglycerides, urea, creatinine and bilirubin level.

Conclusions

S. caseolaris contains bioactive phytoconstituents which may be the possible precursors to isolate and characterize the novel compounds targeting the diseases like allergy and diabetes.

Growing Preferences towards Analog-based Drug Discovery

BACKGROUND

The major concern of today's time is the developing resistance in most of the clinically derived pathogenic micro-organisms for available drugs through several mechanisms. Therefore, there is a dire need to develop novel molecules with drug-like properties that can be effective against the otherwise resistant micro-organisms.

METHODS

New drugs can be developed using several methods like structure-based drug design, ligandbased drug design, or by developing analogs of the available drugs to further improve their effects. However, the smartness is to opt for the techniques that have comparatively less expenditure, lower failure rates, and faster discovery rates.

RESULTS

Analog-Based Drug Design (ABDD) is one such technique that researchers worldwide are opting to develop new drug-like molecules with comparatively lower market values. They start by first designing the analogs sharing structural and pharmacological similarities to the existing drugs. This method embarks on scaffold structures of available drugs already approved by the clinical trials, but are left ineffective because of resistance developed by the pathogens.

CONCLUSION

In this review, we have discussed some recent examples of anti-fungal and anti-bacterial (antimicrobial) drugs that were designed based on the ABDD technique. Also, we have tried to focus on the in silico tools and techniques that can contribute to the designing and computational screening of the analogs, so that these can be further considered for in vitro screening to validate their better biological activities against the pathogens with comparatively reduced rates of failure.

Effect of ketotifen fumarate on experimental autoimmune orchitis and torsion of the spermatic cord

The aim of this work was to study effects of ketotifen fumarate (KF) on prevention of tissue damage in testes of rats with experimental autoimmune orchitis (EAO) and on the contralateral testis in a model of prolonged testicular cord torsion (TCT). Rats with EAO or TCT were injected intraperitoneally once daily with KF or saline solution (vehicle group). Incidence and severity of testicular damage were evaluated by histopathology using an EAO score or a Johnsen score. Mast cells (MC) were identified by histochemistry and quantified. In EAO model, KF significantly reduced severity of histopathological testicular damage compared to rats in the vehicle group. KF also reduced the number of testicular MC compared to vehicle group. Similarly, in TCT model, multifocal damage of the contralateral testis was observed 30 days after testicular torsion characterized by sloughing of the germinal epithelium, seminiferous tubule atrophy, and interstitial edema. Focal signs of inflammation and fibrosis of seminiferous tubular walls were also observed. In contrast, sections of contralateral testis of rats injected with KF and killed 30 days after surgery showed normal histological features. A significant decrease in the number of MC was observed in rats treated with KF compared to untreated animals. In conclusion, we demonstrated that treatment with KF reduced testicular inflammatory process and MC infiltrates in both EAO and TCT models. The results suggest a promising treatment for infertile male patients with testicular pathologies associated with inflammation and germ cell loss.

Histamine

Histamine has at least twenty-three known physiological functions, including playing a prominent role in immunologically mediated inflammation. The structure and metabolism of histamine is discussed, together with the various types of histamine receptors. Histamine plays a role in anaphylaxis, mast cell activation syndromes and mastocytosis and these conditions are relevant to anaesthetic practice. The antihistamine drugs and the H2 receptors agonists are discussed with regard to their role in anaesthesia.

The suppressive effect of dabrafenib, a therapeutic agent for metastatic melanoma, in IgE-mediated allergic inflammation

The functional inhibition of mast cells, which serve as a key effector cells in allergic reactions may be a specific target for treating immunoglobulin (Ig)E-mediated allergic reactions, which occur in various allergic diseases including anaphylaxis, asthma, and atopic dermatitis. In this study, we demonstrated the effects of dabrafenib, a therapeutic agent used to treat metastatic melanoma, with a focus on mast cell activation and local cutaneous anaphylaxis. In two types of mast cells (RBL-2H3 and mouse bone marrow-derived mast cells), dabrafenib (0.01, 0.1, 1 μM) pretreatment significantly decreased IgE-induced degranulation, intracellular calcium influx, and the activity of intracellular signaling molecules, such as Lyn, Syk, Akt, and PLCγ. Dabrafenib ameliorated mRNA and protein expression levels of interleukin-4 and tumor necrosis factor-α by the reduction of nuclear localization of nuclear factor-κB and nuclear factor of activated T-cells. In passive cutaneous anaphylaxis, oral administration of dabrafenib (0.1, 1, 10 mg/kg) reduced local pigmentation and ear thickness in a dose-dependent manner. Taken together, these results suggest that dabrafenib is a therapeutic drug candidate that controls IgE-mediated allergic inflammatory diseases through suppression of mast cell activity.

Green Analytical Methods for the Separation of Seven Antihistamines: Application in Separation of Azelastine and Related Impurities in Nasal Solution

Antihistamines are widely used to alleviate the symptoms caused by allergic reactions. Most of these drugs have zwitteriónicas and/or amphoteric characteristics, which confer additional analytical challenges. This work aimed to develop a single eco-friendly and efficient chromatographic methods for analysis of seven antihistamines, namely, azelastine HCl, desloratadine, ebastine, fexofenadine HCl, ketotifen, loratadine, and olopatadine HCl. The separations were obtained using RP C-18 LUNA (150x4.6mm, 5 μm) column. The mobile phase consisted of acetonitrile and acidified water (pH 2.1) in the following proportion: 15:85, v/v for desloratadine, 25:75, v/v for ketotifen and olopatadine, 32:68, v/v for fexofenadine, 35:65, v/v for azelastine and loratadine, and 45:55, v/v for ebastine. All separations were obtained in less than 7.0 min. A prototype method was fully validated and applied in the assay of azelastine HCl in nasal solutions. The proposed methods for analysis of seven antihistamines are highly efficient, selective, and sensitive. Moreover, all methods can be considered excellent in terms of greenness, with total organic residue < 2.5 mL/analysis. An improved gradient method is also described for separation of azelastine HCl and its related impurities.

Urticaria: A comprehensive review: Treatment of chronic urticaria, special populations, and disease outcomes

Second-generation antihistamines are considered first-line agents in the treatment of chronic urticaria because of their safety and efficacy profile. Some patients require higher doses of H₁ antihistamines alone or in combination with other classes of medications, including H₂ antihistamines, leukotriene receptor antagonists, or first-generation H₁ antihistamines. One major therapeutic advance has been omalizumab, a humanized monoclonal anti-immunoglobulin E that was recently approved by the US Food and Drug Administration for the treatment of chronic urticaria that is unresponsive to H₁ antagonists. In addition, the second article in this continuing medical education series outlines several evidence-based alternative treatments for urticaria and the differences in recommendations between 2 major consensus groups (the European Academy of Allergy and Clinical Immunology/World Allergy Organization and the American Academy of Allergy, Asthma and Immunology/American College of Allergy, Asthma and Immunology Joint Task Force).

A History of Drug Discovery for Treatment of Nausea and Vomiting and the Implications for Future Research

The origins of the major classes of current anti-emetics are examined. Serendipity is a recurrent theme in discovery of their anti-emetic properties and repurposing from one indication to another is a continuing trend. Notably, the discoveries have occurred against a background of company mergers and changing anti-emetic requirements. Major drug classes include: (i) Muscarinic receptor antagonists-originated from historical accounts of plant extracts containing atropine and hyoscine with development stimulated by the need to prevent sea-sickness among soldiers during beach landings; (ii) Histamine receptor antagonists-searching for replacements for the anti-malaria drug quinine, in short supply because of wartime shipping blockade, facilitated the discovery of histamine (H1) antagonists (e.g., dimenhydrinate), followed by serendipitous discovery of anti-emetic activity against motion sickness in a patient undergoing treatment for urticaria; (iii) Phenothiazines and dopamine receptor antagonists-investigations of their pharmacology as "sedatives" (e.g., chlorpromazine) implicated dopamine receptors in emesis, leading to development of selective dopamine (D2) receptor antagonists (e.g., domperidone with poor ability to penetrate the blood-brain barrier) as anti-emetics in chemotherapy and surgery; (iv) Metoclopramide and selective 5-hydroxytryptamine3(5-HT3) receptor antagonists-metoclopramide was initially assumed to act only via D2 receptor antagonism but subsequently its gastric motility stimulant effect (proposed to contribute to the anti-emetic action) was shown to be due to 5-hydroxytryptamine4 receptor agonism. Pre-clinical studies showed that anti-emetic efficacy against the newly-introduced, highly emetic, chemotherapeutic agent cisplatin was due to antagonism at 5-HT3 receptors. The latter led to identification of selective 5-HT3 receptor antagonists (e.g., granisetron), a major breakthrough in treatment of chemotherapy-induced emesis; (v) Neurokinin1receptor antagonists-antagonists of the actions of substance P were developed as analgesics but pre-clinical studies identified broad-spectrum anti-emetic effects; clinical studies showed particular efficacy in the delayed phase of chemotherapy-induced emesis. Finally, the repurposing of different drugs for treatment of nausea and vomiting is examined, particularly during palliative care, and also the challenges in identifying novel anti-emetic drugs, particularly for treatment of nausea as compared to vomiting. We consider the lessons from the past for the future and ask why there has not been a major breakthrough in the last 20 years.

Management of anaphylaxis and allergies in patients with long QT syndrome: A review of the current evidence

OBJECTIVE

To develop a treatment algorithm for patients with long QT syndrome (LQTS) in case they need antiallergic medications for allergic reactions, including asthma and anaphylaxis.

DATA SOURCES

A literature review was performed to assess safety and to develop antiallergic treatment strategies for patients with LQTS.

STUDY SELECTIONS

LQTS is a heterogeneous group of myocardial repolarization disorders characterized by prolongation of the QT interval that potentially results in life-threatening torsades de pointes tachycardia. Data on pharmacologic treatment in case of anaphylaxis in LQTS are sparse. For this narrative review, all currently available articles on the use of antiallergic drugs for allergic reactions, anaphylaxis, and asthma in patients with LQTS were used.

RESULTS

Local allergic symptoms can be safely treated primarily with fexofenadine, levocetirizine, desloratadine, or cetirizine and, if needed, a short course of corticosteroids. In case of systemic symptoms, epinephrine should be administered. It may be less effective in patients with LQTS treated with β-blockers, necessitating the use of glucagon as add-on treatment. In case of lower airway obstruction, ipratropium bromide should be used, but if not effective, inhaled β₂-adrenergic agents may be used. Continuous cardiac monitoring is indicated with the use of epinephrine and inhaled β₂-adrenergic agents. The use of the latter also warrants intense monitoring of serum potassium levels. Clemastine and dimetindene should be avoided in patients with LQTS.

CONCLUSION

Patients with LQTS have a higher risk of life-threatening complications during the treatment of their allergic reactions because of the underlying disease and concomitant treatment with β-blockers. Treatment algorithms will certainly decrease these complications.

Effect of varicocelectomy and/or mast cells stabilizer on sperm DNA fragmentation in infertile patients with varicocele

This study aimed to assess the effect of varicocelectomy and/or mast cells (MCs) stabilizer on sperm DNA fragmentation in infertile men with varicocele (Vx). Overall, 120 infertile patients were randomized to three equal treatment arms; patients that underwent varicocelectomy, patients on 1 mg ketotifen twice daily for three months, and patients that underwent varicocelectomy followed with 1 mg ketotifen twice daily for three months. These patients were subjected to history taking, clinical examination, semen analysis, and estimation of sperm DNA fragmentation index (DFI). After 3 months, all investigated groups showed significant improvement regarding the mean total sperm count, sperm concentration, total sperm motility, and sperm normal forms percentage compared with the pre-treatment data. As well, the mean sperm DFI was significantly improved compared with the pre-treatment data; in men that underwent varicocelectomy (34.6% vs. 28.3%), in men on MC stabilizer only (33.4% vs. 27.8%), and in men that underwent varicocelectomy followed by MC stabilizer (34.3% vs. 25.1%). Sperm DFI improvement percentages showed the highest improvement in men that underwent varicocelectomy followed with MC stabilizer compared with the other two groups (26.8% vs. 18.2%, 16.8%). Sperm DFI improvement percentages showed significant increases in the infertile patients with Vx grade III compared to Vx grade II in all investigated groups. It is concluded that in infertile men associated with Vx and high sperm DFI, surgical repair followed with MCs stabilizer significantly improve sperm DFI compared with either surgical repair or MCs stabilizer alone.

Selecting optimal second-generation antihistamines for allergic rhinitis and urticaria in Asia

Background

Allergic diseases are on the rise in many parts of the world, including the Asia–Pacific (APAC) region. Second-generation antihistamines are the first-line treatment option in the management of allergic rhinitis and urticaria. International guidelines describe the management of these conditions; however, clinicians perceive the additional need to tailor treatment according to patient profiles. This study serves as a consensus of experts from several countries in APAC (Hong Kong, Malaysia, the Philippines, Singapore, Thailand, Vietnam), which aims to describe the unmet needs, practical considerations, challenges, and key decision factors when determining optimal second-generation antihistamines for patients with allergic rhinitis and/or urticaria.

Methods

Specialists from allergology, dermatology, and otorhinolaryngology were surveyed on practical considerations and key decision points when treating patients with allergic rhinitis and/or urticaria.

Results

Clinicians felt the need for additional tools for diagnosis of these diseases and a single drug with all preferred features of an antihistamine. Challenges in treatment include lack of clinician and patient awareness and compliance, financial constraints, and treatment for special patient populations such as those with concomitant disease. Selection of optimal second-generation antihistamines depends on many factors, particularly drug safety and efficacy, impact on psychomotor abilities, and sedation. Country-specific considerations include drug availability and cost-effectiveness. Survey results reveal bilastine as a preferred choice due to its high efficacy and safety, suitability for special patient populations, and the lack of sedative effects.

Conclusions

Compliance to the international guidelines is present among allergists, dermatologists and otorhinolaryngologists; however, this is lower amongst general practitioners (GPs). To increase awareness, allergy education programs targeted at GPs and patients may be beneficial. Updates to the existing international guidelines are suggested in APAC to reflect appropriate management for different patient profiles and varying symptoms of allergic rhinitis and urticaria.

Electronic supplementary material

The online version of this article (doi:10.1186/s12948-017-0074-3) contains supplementary material, which is available to authorized users.

Second generation H1 - antihistamines interaction with food and alcohol-A systematic review

Histamine is a mediator of many physiological processes. It plays an important role in modulating allergy reactions and immune system responses. H1 receptor is a therapeutic target for drugs applied in allergic diseases such as allergic rhinoconjunctivitis, urticarial, or atopic dermatitis. H1-antihistamines display different chemical structures, pharmacokinetics and a potential for drug-drug and drug-food interactions. Drug-food interactions are known to reduce therapeutic effects of the medicine, as well as to induce a potent adverse drug reactions. Considering it all, a systematic review was conducted to investigate the importance of drug-food interaction for H1-antihistamine drugs. As non-sedating second generation H1-antihistamines remain to be drugs of choice in treating allergic conditions, the review has been focused on this particular class of medicines. The aim of this paper is to examine the evidence of food-drug and food-alcohol interactions for second generation H1-antihistamine drugs. A systematic literature queries were performed in the following databases: Medline (via PubMed), Cochrane Library, Embase and Web of Science (all from their inception date till October 2016). The queries covered nine specific names of second generation anthistamine drugs, namely bilastine, cetirizine, desloratadine, ebastine, fexofenadine, levocetirizine, loratadine, mizolastine, and rupatadine, in combinations with such terms as "food", "juice", "grapefruit", "fruits", "alcohol", "pharmacokinetics", and "meal". Additional publications were found by checking all the reference lists. Where none data on drug-food interaction could be found within the investigated databases, a specific drug prescribing information was used. 2326 publications were identified with the database queries. Articles were subjected to analysis by reviewing their title, abstract and full text; duplicated papers were removed. Having collected a complete set of data, a critical review was undertaken. For selected H1-antihistamines food, fruit juices or alcohol consumption may significantly impact the efficacy and safety of the therapy. This issue shall be well understood to educate patients properly, as it provides the major therapeutic element in allergic diseases.

Changes in gene expression induced by histamine, fexofenadine and osthole: Expression of histamine H1 receptor, COX-2, NF-κB, CCR1, chemokine CCL5/RANTES and interleukin-1β in PBMC allergic and non-allergic patients

INTRODUCTION

Fexofenadine (FXF) is a third-generation antihistamine drug and osthole is assumed as a natural antihistamine alternative. This paper compares results of histamine, FXF and osthole impact on HRH-1, COX-2, NF-κB-p50, CCR1 mRNA expression. We also measured mRNA expression of IL-1β and CCL5/RANTES in incubated peripheral blood mononuclear cells (PBMC) to compared how histamine, FXF and osthole had influence on expression level and interacts on product secretion.

OBJECTIVE

The purpose was to investigate expression pattern in asthma PBMC.

METHODS

The cultures were treated 72h with FXF and osthole. We measured mRNA expression of histamine HRH-1, COX-2, NF-κB-p50, CCR1, IL-1β and CCL5/RANTES with Real-Time PCR (RT-PCR).

RESULTS

The present study suggest that osthole may be a potential inhibitor of histamine H₁ receptor activity. We also demonstrated that cells cultured with histamine increase COX-2 mRNA expression and osthole reduce it.

CONCLUSION

Allergy remains one of the most common chronic diseases in Europe and it is rapidly approaching epidemic proportions; with current predictions estimating that the number of allergy-afflicted will equal the healthy population by 2020. It is therefore paramount to find new pharmaceuticals which successfully combat allergic disease.

Virtual Clinical Trial Toward Polytherapy Safety Assessment: Combination of Physiologically Based Pharmacokinetic/Pharmacodynamic-Based Modeling and Simulation Approach With Drug-Drug Interactions Involving Terfenadine as an Example

A Quantitative Systems Pharmacology approach was utilized to predict the cardiac consequences of drug-drug interaction (DDI) at the population level. The Simcyp in vitro-in vivo correlation and physiologically based pharmacokinetic platform was used to predict the pharmacokinetic profile of terfenadine following co-administration of the drug. Electrophysiological effects were simulated using the Cardiac Safety Simulator. The modulation of ion channel activity was dependent on the inhibitory potential of drugs on the main cardiac ion channels and a simulated free heart tissue concentration. ten Tusscher's human ventricular cardiomyocyte model was used to simulate the pseudo-ECG traces and further predict the pharmacodynamic consequences of DDI. Consistent with clinical observations, predicted plasma concentration profiles of terfenadine show considerable intra-subject variability with recorded C_max values below 5 ng/mL for most virtual subjects. The pharmacokinetic and pharmacodynamic effects of inhibitors were predicted with reasonable accuracy. In all cases, a combination of the physiologically based pharmacokinetic and physiology-based pharmacodynamic models was able to differentiate between the terfenadine alone and terfenadine + inhibitor scenario. The range of QT prolongation was comparable in the clinical and virtual studies. The results indicate that mechanistic in vitro-in vivo correlation can be applied to predict the clinical effects of DDI even without comprehensive knowledge on all mechanisms contributing to the interaction.

Antihistamines in the Treatment of Atopic Dermatitis

Background:

Atopic dermatitis (AD) is an inflammatory skin disorder that is exceedingly challenging to treat. A prominent feature of AD is chronic pruritus. Early evidence suggested that pruritus in AD was partially due to mast cell release of histamine. Conversely, recent studies do not validate the role of histamine in the pathogenesis of pruritus. Conventional management continues to include the wide use of antihistamines to treat the persistent itch, however, there is an urgent need for therapy which will reduce the severity of pruritus for these patients.

Objective:

To review the evidence in the literature for the use of antihistamines in the treatment of atopic dermatitis.

Methods:

A MEDLINE search (1966–2002) was performed to obtain studies examining the use of antihistamines in the treatment of atopic dermatitis. Search terms included: atopic dermatitis; eczema; antihistamines; azatadine; brompheniramine; cetirizine; chlorpheniramine; clemastine; cyclizine; cyproheptadine; desloratadine; diphenhydramine; fexofenadine; hydroxyzine; loratadine; meclizine; promethazine; trimeprazine. Further references were gathered from these publications.

Results:

Historically, antihistamines have been used in the treatment of AD. However, this review shows that the evidence for its use is inconclusive. At present, several antihistamines continue to provide relief of pruritus by central sedation, and they can also be used therapeutically for concomitant allergic conditions associated with AD. More clinical trials examining the therapeutic efficacy of antihistamines, especially with the newer nonsedating antihistamines, are necessary to elucidate their role in the treatment of AD.

Conclusion:

Dermatologists require additional evidence regarding the efficacy of antihistamines and their mechanism of action in the treatment of AD to enhance patient care.

Management of Allergic Rhinitisand Sinusitis

Allergic rhinitis and sinusitis are chronic conditions of the airway and cause significant morbidity. Both can require pharmacotherapy with nonprescription products to relieve symptoms or with prescription products to treat the underlying pathophysiology. Because these diseases are prevalent conditions, the pharmacist is in the unique position of being the first health professional contact for many patients. The pharmacist can assist the patient in selection of nonprescription antihistamines, decongestants, and nasal saline sprays as well as provide instruction on the use of steam therapy, aromatic vapors, and warm compresses for the relief of symptoms. Equally important, the pharmacist can encourage patients to seek care from a physician when treatment with intranasal corticosteroids, antibiotics, and nonsedating antihistamines are needed.

Observations on conducting whole-cell patch clamping of the hERG cardiac K+ channel in pure human serum

Inhibition of the human ether-a-go-go-related gene (hERG) K⁺ channel by drugs leads to QT prolongation on the electrocardiogram and can result in serious cardiac arrhythmia. For this reason, screening of drugs on hERG is mandatory during the drug development process. Patch clamp electrophysiology in a defined physiological saline solution (PSS) represents the standard method for assaying drug effects on the channel. To make the assay more translatable to clinical studies, we have conducted whole-cell patch clamping of hERG using pure human serum as the extracellular medium. Pure human serum had little effect on the hERG channel waveform or the current-voltage relationship when compared to PSS. hERG current recordings were highly stable in serum at room temperature, but prolonged recordings at the physiological temperature required prior heat inactivation of the serum. Compared to PSS, the IC₅₀ values, conducted at room temperature, of the classic hERG blocking drugs cisapride, moxifloxacin, and terfenadine were shifted to the right by an extent predicted by their known plasma protein binding, but we did not detect any differences in IC₅₀ s between male and female serum. Total plasma levels of these drugs associated with clinical QT prolongation corresponded to small (<15%) inhibition of hERG current in pure serum suggesting that minor inhibition of the channel leads to observable pharmacodynamic effects. Conducting whole-cell patch clamping of hERG in human serum has the potential to make the assay more translatable to clinical studies and improve its predictive value for safety testing. Copyright © 2016 John Wiley & Sons, Ltd.

Role of the Histamine H3 Receptor in the Central Nervous System

The G_i/o protein-coupled histamine H₃ receptor is distributed throughout the central nervous system including areas like cerebral cortex, hippocampus and striatum with the density being highest in the posterior hypothalamus, i.e. the area in which the histaminergic cell bodies are located. In contrast to the other histamine receptor subtypes (H₁, H₂ and H₄), the H₃ receptor is located presynaptically and shows a constitutive activity. In detail, H₃ receptors are involved in the inhibition of histamine release (presynaptic autoreceptor), impulse flow along the histaminergic neurones (somadendritic autoreceptor) and histamine synthesis. Moreover, they occur as inhibitory presynaptic heteroreceptors on serotoninergic, noradrenergic, dopaminergic, glutamatergic, GABAergic and perhaps cholinergic neurones. This review shows for four functions of the brain that the H₃ receptor represents a brake against the wake-promoting, anticonvulsant and anorectic effect of histamine (via postsynaptic H₁ receptors) and its procognitive activity (via postsynaptic H₁ and H₂ receptors). Indeed, H₁ agonists and H₃ inverse agonists elicit essentially the same effects, at least in rodents; these effects are opposite in direction to those elicited by brain-penetrating H₁ receptor antagonists in humans. Although the benefit for H₃ inverse agonists for the symptomatic treatment of dementias is inconclusive, several members of this group have shown a marked potential for the treatment of disorders associated with excessive daytime sleepiness. In March 2016, the European Commission granted a marketing authorisation for pitolisant (Wakix^R) (as the first representative of the H₃ inverse agonists) for the treatment of narcolepsy.

Clinical practice. Allergic rhinitis

A 35-year-old woman has a history of nasal congestion on most days of the year, dating back to her late teens. She has chronic nasal drainage, which is clear and thick. Her congestion is worst in the late summer and early fall and again in the early spring; at these times, she also has sneezing, nasal itching, and cough. Five years ago, she had an episode of shortness of breath with wheezing on a day when her nasal symptoms were severe, but this episode resolved spontaneously and has not recurred. Her eyes do not bother her. Over-the-counter oral antihistamines help her symptoms a little, as do nasal decongestants, which she uses occasionally. Her 6-year-old son has similar symptoms. How should this case be managed?

Development and validation of a rapid stability indicating HPLC-method using monolithic stationary phase and two spectrophotometric methods for determination of antihistaminic acrivastine in capsules

Simple, rapid and accurate high performance liquid chromatographic (HPLC) and spectrophotometric methods are described for determination of antihistaminic acrivastine in capsules. The first method (method A) is based on accurate, sensitive and stability indicating chromatographic separation method. Chromolith® Performance RP-18e column, a relatively new packing material consisting of monolithic rods of highly porous silica, was used as stationary phase applying isocratic binary mobile phase of ACN and 25 mM NaH2PO4 pH 4.0 in the ratio of 22.5:77.5 at flow rate of 5.0 mL/min and 40°C. A diode array detector was used at 254 nm for detection. The elution time of acrivastine was found to be 2.080±0.032. The second and third methods (methods B and C) are based on the oxidation of acrivastine with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with, metol-sulphanilic acid (λmax: 520 nm) or amaranth dye (λmax: 530 nm). The reacted oxidant corresponds to the drug content. Beer's law is obeyed over the concentration range 1.563-50, 2.0-20 and 1.0-10 μg mL(-1) for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 μg mL(-1) and 0.782, 0.973 and 0.376 μg mL(-1) for methods A, B and C, respectively. The HPLC method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. Stability tests were done through exposure of the analyte solution for four different stress conditions and the results indicate no interference of degradants with HPLC-method. The proposed methods was favorably applied for determination of acrivastine in capsules formulation. Statistical comparison of the obtained results from the analysis of the studied drug to those of the reported method using t- and F-tests showed no significant difference between them.

Palladium-catalyzed chemoselective allylic substitution, Suzuki-Miyaura cross-coupling, and allene formation of bifunctional 2-B(pin)-substituted allylic acetate derivatives

A formidable challenge at the forefront of organic synthesis is the control of chemoselectivity to enable the selective formation of diverse structural motifs from a readily available substrate class. Presented herein is a detailed study of chemoselectivity with palladium-based phosphane catalysts and readily available 2-B(pin)-substituted allylic acetates, benzoates, and carbonates. Depending on the choice of reagents, catalysts, and reaction conditions, 2-B(pin)-substituted allylic acetates and derivatives can be steered into one of three reaction manifolds: allylic substitution, Suzuki-Miyaura cross-coupling, or elimination to form allenes, all with excellent chemoselectivity. Studies on the chemoselectivity of Pd catalysts in their reactivity with boron-bearing allylic acetate derivatives led to the development of diverse and practical reactions with potential utility in synthetic organic chemistry.

Implication of novel thiazolo-thiophene derivative (MCD-KV-10) for management of asthma

CONTEXT

Asthma is multifaceted disease where many targets contribute towards its development and progression. Among these, adenosine receptor subtypes play a major role.

OBJECTIVE

MCD-KV-10, a novel thiazolo-thiophene was designed and evaluated pre-clinically for its implication in management of asthma.

MATERIALS AND METHODS

This compound showed good affinity and selectivity towards A(2A)/A3 adenosine receptor (AR) subtypes. Furthermore, MCD-KV-10 was evaluated for in vitro lipoxygenase inhibition activity; in vivo mast cell stabilization potential and in vivo anti-asthmatic activity was done in ovalbumin-induced airway inflammation model in guinea pigs.

RESULTS

The compound showed good (>57%) inhibition of lipoxygenase enzyme and also effectively protected mast cell degranulation (>63%). The compound showed good anti-asthmatic activity as inferred from the in vivo studies.

DISCUSSION

These results indicate that MCD-KV-10 has an inhibitory effect on airway inflammation.

CONCLUSION

Though, we have identified a potential candidate for management of asthma, further mechanistic studies are needed.

Effect of azelastine on cardiac repolarization of guinea-pig cardiomyocytes, hERG K⁺ channel, and human L-type and T-type Ca²⁺ channel

Azelastine is a second generation histamine H₁-receptor antagonist used as an anti-asthmatic and anti-allergic drug that can induce QT prolongation and torsades de pointes. We investigated the acute effects of azelastine on human ether-a-go-go-related gene (hERG) channels, action potential duration (APD), and L-type (I(Ca,L)) and T-type Ca²⁺ current (I(Ca,T)) to determine the electrophysiological basis for its proarrhythmic potential. Azelastine increased the APD at 90% of repolarization concentration dependently, with an IC₅₀ of 1.08 nM in guinea-pig ventricular myocytes. We examined the effects of azelastine on the hERG channels expressed in Xenopus oocytes and HEK293 cells using two-microelectrode voltage-clamp and patch-clamp techniques. Azelastine induced a concentration-dependent decrease of the hERG current amplitude at the end of the voltage steps and tail currents. The IC₅₀ for the azelastine-induced block of the hERG currents expressed in HEK293 cells was 11.43 nM, while the drug inhibited I(Ca,L) and I(Ca,T) with IC₅₀ values of 7.60 and 26.21 μM, respectively. The S6 domain mutations, Y652A partially attenuated and F656A abolished hERG current block. These results suggest that azelastine is a potent blocker of hERG channels rather than I(Ca,L) or I(Ca,T), providing molecular mechanisms for the arrhythmogenic side effects during the clinical administration of azelastine.

Ketotifen, a mast cell blocker improves sperm motility in asthenospermic infertile men

AIM

This study aimed to evaluate the efficacy of ketotifen on sperm motility of asthenospermic infertile men.

SETTING AND DESIGN

It is a prospective study designed in vivo.

MATERIALS AND METHODS

In this interventional experimental study, a total of 40 infertile couples with asthenospermic infertility factor undergoing assisted reproductive technology (ART) cycles were enrolled. The couples were randomly assigned to one of two groups at the starting of the cycle. In control group (n = 20), the men did not receive Ketotifen, while in experiment group (n = 20), the men received oraly ketotifen (1 mg Bid) for 2 months. Semen analysis, under optimal circumferences, was obtained prior to initiation of treatment. The second semen analysis was done 2-3 weeks after stopped ketotifen treatment and sperm motility was defined. Clinical pregnancy was identified as the presence of a fetal sac by vaginal ultrasound examination.

STATISTICAL ANALYSIS USED

All data are expressed as the mean ± standard error of mean (SEM). t test was used for comparing the data of the control and treated groups.

RESULTS

The mean sperm motility increased significantly (from 16.7% to 21.4%) after ketotifen treatment (P < 0.001). This sperm motility improvement was more pronounced in the primary infertility cases (P < 0.003). The rate of pregnancy was 12.5% in infertile couples that their men receiving 1 mg/twice a day ketotifen. In 52% of infertile men's semen, the percentage of sperm motility was increased from 5% to 35% and this sperm motility improvement was also observed in 33% of necrospermia (0% motility) cases.

CONCLUSION

These results suggest that ketotifen may represent as a novel therapeutic approach to improve sperm motility in the infertile men with cause of asthenospermia or necrospermia.

Sleep and neurocognitive functioning in children with eczema

Sleep disruption in childhood is associated with clearly defined deficits in neurocognition and behaviour. Childhood eczema is also a potent cause of sleep disruption though it is unknown whether it too results in neurocognitive deficits. To test this hypothesis, neurocognitive (WISC-IV), parental-reported sleep quality (Sleep Disturbance Scale of Children (SDSC)) and overnight polysomnographic (PSG) data were collected in 21 children with eczema and 20 healthy controls (age range 6-16 years). Children with eczema had worse sleep quality on both PSG (notably increased nocturnal wakefulness, a higher number of stage shifts and a longer latency to REM onset) and parental report. In addition, they demonstrated significant neurocognitive deficits (especially verbal comprehension, perceptual reasoning and to a lesser extent working memory) with a composite Full Scale IQ 16 points lower than controls. Parental reported sleep problems but not PSG parameters were correlated with reduced neurocognitive performance. However, hierarchical regression analyses revealed that eczema status was predictive while sleep fragmentation (parental or PSG) was not predictive of neurocognitive performance. As this is the first study to systematically examine neurocognitive functioning in children with eczema and given the finding of significant deficits it merits replication especially given the prevalence of the condition. The unanswered question is whether these cognitive deficits normalise with effective eczema treatment and if this is mediated by improvements in sleep architecture.

A class of tricyclic compounds blocking malaria parasite oocyst development and transmission

Malaria is a deadly infectious disease in many tropical and subtropical countries. Previous efforts to eradicate malaria have failed, largely due to the emergence of drug-resistant parasites, insecticide-resistant mosquitoes and, in particular, the lack of drugs or vaccines to block parasite transmission. ATP-binding cassette (ABC) transporters are known to play a role in drug transport, metabolism, and resistance in many organisms, including malaria parasites. To investigate whether a Plasmodium falciparum ABC transporter (Pf14_0244 or PfABCG2) modulates parasite susceptibility to chemical compounds or plays a role in drug resistance, we disrupted the gene encoding PfABCG2, screened the recombinant and the wild-type 3D7 parasites against a library containing 2,816 drugs approved for human or animal use, and identified an antihistamine (ketotifen) that became less active against the PfABCG2-disrupted parasite in culture. In addition to some activity against asexual stages and gametocytes, ketotifen was highly potent in blocking oocyst development of P. falciparum and the rodent parasite Plasmodium yoelii in mosquitoes. Tests of structurally related tricyclic compounds identified additional compounds with similar activities in inhibiting transmission. Additionally, ketotifen appeared to have some activity against relapse of Plasmodium cynomolgi infection in rhesus monkeys. Further clinical evaluation of ketotifen and related compounds, including synthetic new derivatives, in blocking malaria transmission may provide new weapons for the current effort of malaria eradication.

Predicting and establishing the clinical efficacy of a histamine h(1)-receptor antagonist : desloratadine, the model paradigm

Antihistamines are well established as a mainstay for treating allergic diseases, including seasonal and perennial allergic rhinitis as well as other conditions, such as chronic idiopathic urticaria. The development of new antihistamines is a multistage process that includes in vitro and in vivo assessments of the antihistaminic, anti-inflammatory and antiallergic properties of new therapies. Results of these assessments are critical for predicting and establishing the clinical efficacy of an antihistamine. The focus of this article is to review the investigational methods used to assess the efficacy, safety and tolerability of newer histamine H(1)-receptor antagonists. Desloratadine, a new-generation H(1)-receptor antagonist, was chosen to illustrate the use of this model paradigm. Data obtained from two large observational studies are presented, confirming results obtained from clinical trials that the in vitro inhibition of release of inflammatory mediators such as histamine, prostaglandins, leukotrienes and the reduction of secretion of cytokines such as IL-4 and IL-13 at physiological concentrations is reflected in increased efficacy, particularly upon nasal obstruction. A recent discovery that des- loratadine inhibits nuclear factor-kappaB may be the underlying explanation for much of this extra anti-inflammatory activity.

Induction of prolonged, continuous slow-wave sleep by blocking cerebral H₁ histamine receptors in rats

BACKGROUND AND PURPOSE

Classic H(1) histamine receptor (H(1)R) antagonists are non-selective for H(1)R and known to produce drowsiness. Modern antihistamines are more selective for H(1)R, and are 'non-drowsy' presumably due to reduced permeability through the blood-brain barrier. To characterize both histaminergic sleep regulation and the central actions of antihistamines, in the present study we analysed the effect of classic and modern antihistamines on rats' sleep using continuous i.c.v. infusions.

EXPERIMENTAL APPROACH

Effects of classic (d-chlorpheniramine; d-CPA) and second-generation (cetirizine) antihistamines on sleep were compared after i.p. injections or continuous i.c.v. infusions into rats. Fluorescent cetirizine/DBD-pz was synthesized to trace the approximate distribution of cerebral cetirizine. Furthermore, the effects of H(1) R antagonists on cultured preoptic neurons were examined using calcium imaging.

KEY RESULTS

d-CPA 4 mg·kg(-1) i.p. increased non-rapid eye movement (REM) sleep whereas 10-40 mg·kg(-1) d-CPA decreased non-REM sleep at dark onset time. Nocturnal i.c.v. infusions of d-CPA (10 µmol·100 µL(-1)·10 h(-1)) increased drowsiness but not non-REM sleep, whereas the same i.c.v. infusions of cetirizine significantly increased non-REM sleep, abolished REM sleep, and decreased wakefulness for more than 10 h. The medial preoptic area contained the greatest fluorescent labelling after i.c.v. cetirizine/DBD-pz infusions. Histamine-induced Ca(2+) increases in medial preoptic neurons were blocked by d-CPA or cetirizine, whereas d-CPA, but not cetirizine, increased Ca(2+) irrespective of antihistaminergic activity at ≥ 100 µM.

CONCLUSION AND IMPLICATIONS

The excitatory action of d-CPA may explain the seemingly inconsistent actions of d-CPA on sleep. Cerebral H(1)R inhibition by cetirizine induces synchronization of cerebral activity and prolonged, continuous slow-wave sleep.