H1-Antihistamines: more relevant than ever in the treatment of allergic disorders

A sleep clinician's guide to runny noses: evaluation and management of chronic rhinosinusitis to improve sleep apnea care in adults

STUDY OBJECTIVES

The treatment of obstructive sleep apnea is often impeded by intolerance of positive airway pressure therapy, which is frequently attributed to the inability to breathe through the nose. Providers caring for patients with sleep apnea need a working knowledge of nasal passage disease and available treatments to better manage this common comorbidity.

METHODS

This review examines the literature connecting rhinosinusitis to adverse sleep and sleep apnea outcomes. It explores the different types of nasal and sinus diseases a sleep apnea provider might encounter, focusing on the medications used to treat them and indications for referral to otolaryngology.

RESULTS

Chronic rhinosinusitis can be either allergic or nonallergic. Both types can interfere with sleep and sleep apnea therapy. The successful management of chronic rhinosinusitis can improve positive airway pressure tolerance and adherence. A wide range of over-the-counter and prescription pharmacotherapy is available, with data supporting intranasal over oral treatment. Surgical treatment for chronic rhinosinusitis in obstructive sleep apnea addresses nasal obstruction, often with inferior turbinate reduction and septoplasty.

CONCLUSIONS

Sleep specialists should have a working knowledge of the available options to treat chronic rhinosinusitis. These options are often safe, effective, and readily accessible. Otolaryngologists and allergists/immunologists provide additional treatment options for more complicated patients. Providing treatment for chronic rhinosinusitis should be included as part of comprehensive sleep apnea care.

CITATION

Ali MM, Ellison M, Iweala OI, Spector AR. A sleep clinician's guide to runny noses: evaluation and management of chronic rhinosinusitis to improve sleep apnea care in adults. J Clin Sleep Med. 2023;19(8):1545-1552.

Efficacy of cationic amphiphilic antihistamines on outcomes of patients treated with immune checkpoint inhibitors

BACKGROUND

Cationic amphiphilic antihistamines have been shown to improve patient outcomes in immunogenic tumours, but whether they can augment and improve response to immunotherapy is unknown. We aim to evaluate the effect of cationic amphiphilic antihistamines in patients receiving immune checkpoint inhibitors (ICIs).

METHODS

We conducted a retrospective propensity score-matched cohort study at two tertiary referral centres in Taiwan between January 2015 and December 2021. Patients who received desloratadine, cyproheptadine, and ebastine were classified as cationic amphiphilic antihistamine users. The primary outcome was overall survival, and the secondary outcomes were progression-free survival and clinical benefit rate. Patients treated with cationic amphiphilic antihistamines were matched to patients who received non-cationic amphiphilic antihistamines based on variables including age, cancer type, stage, and history of allergic diseases.

RESULTS

A total of 734 ICI-treated patients were included. After matching, 68 cationic amphiphilic antihistamine and non-cationic amphiphilic antihistamine users remained for analysis. Compared with non-cationic amphiphilic antihistamine users, patients who received cationic amphiphilic antihistamines had a significantly longer median overall survival (24.8 versus 10.4 months; Log-rank, p = 0.018) and progression-free survival (10.6 versus 4.93 months; Log-rank, p = 0.004). The use of cationic amphiphilic antihistamines was associated with an approximately 50% lower risk of all-cause mortality (HR, 0.55 [95% CI: 0.34-0.91]). Survival benefits were not seen in patients who received cationic amphiphilic antihistamines before immune checkpoint blockade. These survival benefits were observed regardless of the generation of cationic amphiphilic antihistamines.

CONCLUSION

The use of cationic amphiphilic antihistamines was associated with improved survival among patients treated with immunotherapy.

Post-Burn Pruritus

Post-burn pruritus is the pruritus that occurs after burn during the rehabilitation and healing process of burn wounds. The post-burn pruritus is a common and serious complication of burn injury, which severely lowers the quality of life of the patient. Many potential treatments are available for pruritus but there is no consensus of the best single treatment yet. The precise mechanism of post-burn pruritus has not been elucidated, but it appears to have pruritogenic and neuropathic aspects. Clinically, post-burn pruritus tends to be intractable to conventional treatment but rather responds to neuroleptic agents, such as gabapentin and pregabalin. During wound healing, various neuropeptides secreted from the nerves of the skin control epidermal and vascular proliferation and connective tissue cells. When keratinocytes are activated by an itch-inducing substance, they secrete a variety of inflammatory substances that increase the susceptibility of the itch receptor. There are two mechanisms underlying post-burn neuropathic pruritus. The first one is peripheral sensitization. The second one is the intact nociceptor hypothesis. An effective treatment for post-burn pruritus will also be effective in other neuropathic and intractable itching. In this review, we summarized the interaction and mechanism of keratinocytes, immune cells, and nerve fibers related to post-burn pruritus.

Anaphylaxis to Chlorpheniramine Maleate and Literature Review

Chlorpheniramine maleate is commonly used antihistamine. Since antihistamines are the main therapeutic agents for symptomatic treatment of urticaria, anaphylaxis to antihistamines may lead to errors in diagnosis and treatment. We report a case of anaphylaxis induced by chlorpheniramine maleate confirmed by intradermal test. A 35-year-old female experienced history of anaphylaxis after intramuscular injection of chlorpheniramine maleate. Skin prick test was negative, but intradermal test was positive. Patient also experienced mild dizziness after intradermal test and refused to perform any further evaluation such as oral challenge test. Anaphylaxis for chlorpheniramine maleate is very rare but should be considered.

Histamine, histamine receptors, and neuropathic pain relief

Histamine, acting via distinct histamine H₁, H₂, H₃, and H₄ receptors, regulates various physiological and pathological processes, including pain. In the last two decades, there has been a particular increase in evidence to support the involvement of H₃ receptor and H₄ receptor in the modulation of neuropathic pain, which remains challenging in terms of management. However, recent data show contrasting effects on neuropathic pain due to multiple factors that determine the pharmacological responses of histamine receptors and their underlying signal transduction properties (e.g., localization on either the presynaptic or postsynaptic neuronal membranes). This review summarizes the most recent findings on the role of histamine and the effects mediated by the four histamine receptors in response to the various stimuli associated with and promoting neuropathic pain. We particularly focus on mechanisms underlying histamine‐mediated analgesia, as we aim to clarify the analgesic potential of histamine receptor ligands in neuropathic pain.

Linked Articles

This article is part of a themed section on New Uses for 21st Century. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.3/issuetoc

A multicenter study on the efficacy and safety of So-Cheong-Ryong-Tang for perennial allergic rhinitis

BACKGROUND

So-Cheong-Ryong-Tang (SCRT), also known as Xiao-Qing-Long-Tang or Sho-seiryo-to, is a mixed herbal formula that is used to treat allergic rhinitis, bronchitis, allergic asthma, and common cold in traditional Korean medicine.

OBJECTIVE

To assess the efficacy and safety of the SCRT for the treatment of allergic rhinitis.

METHODS

We conducted a double-blind, randomized, placebo-controlled, parallel-group, multicenter study of Korean adults with perennial allergic rhinitis. The trial consisted of a 4-week oral administration of SCRT or placebo, with two visits at 2-week intervals, and an 8-week follow-up period, with two visits at 4-week intervals. The primary outcome was a change in the total nasal symptoms score. The secondary outcomes included changes in the Rhinoconjunctivitis Quality of Life Questionnaire score, total serum immunoglobulin E (IgE), cytokines levels, and nasal endoscopy index.

RESULTS

SCRT improved nasal symptoms and quality of life in patients with PAR after 4 weeks medication, and these effects did not last 8 weeks after the end of medication. The level of serum IgE, eosinophil counts, and cytokines did not alter after medication. Nasal endoscopy index did not show significant difference. No serious AEs and safety assessment changes were observed in this trial.

CONCLUSION

SCRT is an effective and safe medication for patients with chronic, perennial, and moderate to severe AR. A clinical study with a >4-week period of medication use, and more participants for immune material test is needed to investigate the long-term efficacy of SCRT in relieving the symptoms of nasal obstruction and identifying the underlying mechanisms of action and indications for traditional Korean medicine.

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.

Efficacy and safety of So-Cheong-Ryong-Tang in treatment of perennial allergic rhinitis: study protocol for a double-blind, randomised, parallel-group, multicentre trial

INTRODUCTION

So-Cheong-Ryong-Tang (SCRT) is a herbal medicine widely used in traditional medicine for treating allergic rhinitis (AR). In animal studies, SCRT has suppressed the progression of AR. The main purpose of this study is to assess the efficacy and safety of the SCRT for the treatment of perennial allergic rhinitis (PAR) and discover the underlying mechanisms resulting in anti-inflammatory effects in humans.

METHODS AND ANALYSIS

We will conduct a double-blind, randomised, placebo-controlled, parallel-group, multicentre trial of Korean adults with PAR. For the study, 156 subjects with PAR will be recruited. The trial will consist of a 4-week oral administration of SCRT or placebo with two visits at 2-week intervals and an 8-week follow-up period with two visits at 4-week intervals. The primary outcome is a change in the total nasal symptoms score. The secondary outcomes include changes in the Rhinoconjunctivitis Quality of Life Questionnaire score, total serum IgE and cytokines levels.

ETHICS AND DISSEMINATION

This study was approved by the Institutional Review Board at each research centre (name of each centres and approval numbers): Kyung Hee University Hospital at Gangdong (KHNMC-OH-IRB 2015-04-009), Kyung Hee University Medical Centre (KOMCIRB-160321-HRBR-011), Pusan National University Hospital (2016-004), Dongguk University Medical Centre (2016-03) and Semyung University hospital (2016-01). This result will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT03009136; Pre-results.

Hyeonggaeyeongyo-Tang for Treatment of Allergic and Nonallergic Rhinitis: A Prospective, Nonrandomized, Pre-Post Study

Hyeonggaeyeongyo-tang (HYT) is an ancient formula of oriental medicine traditionally used to treat rhinitis; however, clinical evidence has not yet been established. The aim of this study was to investigate the short-term and long-term efficacy and safety of HYT for chronic rhinitis. Adult subjects with chronic rhinitis symptoms were recruited. The subjects received HYT for 4 weeks and had follow-up period of 8 weeks. Any medicines used to treat nasal symptoms were not permitted during the study. The skin prick test was performed to distinguish the subjects with allergic rhinitis from those with nonallergic rhinitis. After treatment, the total nasal symptoms score and the Rhinoconjunctivitis Quality of Life Questionnaire score significantly improved in the whole subject group, in the allergic rhinitis group, and in the nonallergic rhinitis group, with no adverse events. This improvement lasted during a follow-up period of 8 weeks. Total IgE and eosinophil levels showed no significant difference after treatment in the allergic rhinitis group. HYT improved nasal symptoms and quality of life in patients with allergic rhinitis and nonallergic rhinitis. This is the first clinical study to evaluate the use of HYT to treat patients with rhinitis. This trial has been registered with the ClinicalTrials.gov Identifier NCT02477293.

Atopic dermatitis and allergic rhinitis--do co-effects in therapy exist?

Atopic dermatitis and allergic rhinitis frequently appear together in the same patients. The pathogenesis of both disorders is complex and still incompletely understood. Nevertheless, pathophysiological overlaps suggest the existence of potential therapeutic co-effects. While data pointing towards a positive effect of allergen elimination for both diseases is still limited, there is now increasing evidence showing beneficial effects of specific immunotherapy in patients suffering from atopic dermatitis and additional type I allergies. H(1)-antihistamines were also found to exert moderate positive effects on the symptoms of atopic dermatitis in single studies. In summary, a limited therapeutic co-effect of the above mentioned treatment options can be expected in case of the parallel existence of atopic dermatitis and allergic rhinitis in the same patient. More studies on this issue during the next years are desirable. In addition, a better understanding of the pathophysiology should have a positive impact on the treatment of atopic manifestations such as atopic dermatitis and allergic rhinitis.

Clinical practice: Allergen-specific immunotherapy in children: facts and FAQs

Allergen-specific immunotherapy (SIT) in its various application forms represents the main treatment approach of IgE-mediated allergic diseases in adults and children. Despite this clear recommendation, many particularities of products, patient characteristics, and product availability in different countries hamper the use of allergen-specific immunotherapy in particular in children. The frequently asked questions by parents, patients, and physicians are the backbone of this review. Thus, the potentials and limitations of allergen-specific immunotherapy in children and adolescents will be highlighted. IgE-mediated allergic diseases are affecting about 20% of the population. They manifest commonly early in life, and hence, the use of SIT should be considered also early in the course of the disease.

Levocetirizine: a modern H1-antihistamine for the treatment of allergic rhinitis

Levocetirizine is the latest of the H(1)-antihistamines indicated for adults and children (as young as 2 years old) suffering from allergic rhinitis and chronic idiopathic urticaria. Currently, it is the only therapy registered for treatment of persistent allergic rhinitis, as defined by the Allergic Rhinitis & its Impact on Asthma guidelines. Pharmacologic studies have shown levocetirizine to have a more favorable pharmacokinetic/pharmacodynamic profile than other commonly employed H(1)-antihistamines. This reflects its superiority in controlling the symptoms of seasonal, perennial and persistent allergic rhinitis in well-controlled trials. Clinical trials and postmarketing surveillance have indicated that levocetirizine is safe and well tolerated, and leads to clinically significant improvements in the quality of life of patients. It is also reported to reduce comorbidities as well as overall treatment costs when administered continuously over the longterm.

An unusual cause of hypotension and abnormal electrocardiogram (ECG) — scombroid poisoning

Scombroid fish or histamine food poisoning is an illness typically associated with fish consumption, rarely encountered and reported in Europe. Symptoms develop quickly and resemble an allergic reaction. This paper reports three cases of severe scombroid poisoning in previously healthy patients, which presented diffuse macular erythema, hypotension, palpitations, and abnormal electrocardiogram (ECG). All patients required intensive care, with a complete resolution of symptoms and ECG changes within 24 hours. This is the first Romanian report of scombroid poisoning, emphasizing that medical personnel should be aware of this condition, because symptoms and ECG changes often lead to confusion with other diseases.

[Allergen-specific Immunotherapy for children and adolescents - a review on available products in Austria]

A pediatric consensus report on allergen-specific immunotherapy for children and adolescents is presented for Austria. Products on the market in Austria are presented and categorised according to studies performed on the target population of children and adolescents, their effectiveness and indication. In general, more clinical studies on children and adolescents are mandatory for most of the available allergen-specific immunotherapeutics. In addition, the use of allergen-specific immunotherapy in general should be promoted as the exclusive treatment with long-lasting effects in type I allergies in particular in children.

Pruritus in burns: review article

Pruritus represents a common and distressing feature of burn wounds. Over the last decades, significant advances in neuroanatomical and neurophysiological knowledge have resulted in the elucidation of the mediators and pathways involved in the transmission of pruritic impulses. A plethora of therapeutic approaches have been evaluated mostly in small-scale studies involving burns patients targeting both the peripheral and the central components of the neurologic pathway. Antihistamines, doxepin, massage therapy, and transcutaneous electrical nerve stimulation are effective strategies to combat pruritus in burns patients. Recent studies have provided preliminary evidence regarding the effectiveness of gabapentin and ondansetron. The area of burns pruritus is under-researched and large-scale studies are required to reinforce the armamentarium of specialists with evidence-based regimens for the treatment of this highly distressing symptom.

New oral H1 antihistamines in children: facts and unmeet needs

BACKGROUND

Second-generation antihistamines differ from first-generation ones because of their elevated specificity and affinity for peripheral H1-receptors and because of their lower penetration to the central nervous system, having fewer sedative effects as a result. Over the last few years, new compounds with different pharmacokinetic properties have been synthesized. More recent improvements of the molecules, generally in the form of active metabolites, led to the synthesis of new-generation antihistamines.

METHODS

Recommendations on the minimum criteria that would have to be met for compounds to be classified as new-generation antihistamines have been recently established by a consensus statement. In the past, the pharmacokinetics and pharmacodynamics of H1 antihistamines have not been optimally investigated in the pediatric population, especially in infants and young children.

RESULTS

The pharmacology of second-generation H1 antihistamines has been investigated relatively deeper than old antihistamines in children. In the pediatric population, clinical studies with new-generation antihistamines are still limited in number and, with rare exceptions, of brief duration. Comparative trials on the efficacy and safety between different compounds are also lacking.

CONCLUSIONS

Properly designed, long-term trials with new-generation H1 antihistamines need to be performed in single age groups, in order to better define the effects of these drugs in all pediatric population.

Time-dependent inhibition of histamine-induced cutaneous responses by oral and intramuscular diphenhydramine and oral fexofenadine

BACKGROUND

Diphenhydramine is often the treatment of choice for acute urticarial or allergic reactions despite its adverse effects of sedation and impairment. Second- and third-generation histamine1-antihistamines are generally devoid of these adverse effects but are typically not used because of a perceived slower onset of action.

OBJECTIVE

To examine the time-dependent effects of oral fexofenadine and oral and intramuscular diphenhydramine to reduce histamine-induced wheal-and-flare responses.

METHODS

Eighteen healthy patients were included in a double-blind, placebo-controlled, 3-way, randomized, crossover study with oral fexofenadine (180 mg) and oral and intramuscular diphenhydramine (50 mg). Histamine-induced skin tests were performed before and more than 6 hours subsequent to dosing. The primary end point was time to induce a 50% reduction in histamine-induced flare. Secondary end points included change from baseline at each time point in wheal-and-flare responses and area under the curve at more than 6 hours for flare.

RESULTS

No significant differences were found in the 50% inhibitory responses of histamine-induced flares among the 3 groups (P = .09). No significant differences were found among the 3 groups in change from baseline at each time point except for 30 minutes during which fexofenadine had no inhibitory effect. Area under the curve analyses for wheal-and-flare responses revealed no differences among treatments at more than 6 hours.

CONCLUSION

Diphenhydramine tended to work more rapidly than fexofenadine, but the differences were not statistically significant. Given the adverse effect profile of diphenhydramine, but only marginal onset of action advantage, the risk-to-benefit ratio may be more favorable for oral fexofenadine when treating an acute urticarial or allergic reaction.

A survey of emergency department management of acute urticaria in children

OBJECTIVES

To describe emergency department management of acute urticaria in children and to determine factors associated with management strategies and adherence to practice guidelines.

METHODS

Self-administered cross-sectional survey mailed to all Section of Emergency Medicine members of the American Academy of Pediatrics (n = 1190) and 1000 randomly selected members of the American College of Emergency Physicians. Main outcome measure was proportion of respondents adhering to published guidelines. Factors associated with management strategies were analyzed using bivariate and logistic regression analyses.

RESULTS

Of 2190 surveys sent, 1137 (52.5%) were available for analysis. Respondents included 44.6% pediatric emergency physicians, 36.4% emergency physicians, and 15.3% pediatricians. First-generation histamine (H)1 antagonists alone were the most common therapy used on initial presentation of acute urticaria, followed by corticosteroids, H2 antagonists, and second-generation H1 antagonists, used by only 7.8%, despite their recommendation as first-line therapy. Physicians working in an emergency department as opposed to an urgent or primary care setting were less likely to use second-generation H1 antagonists (odds ratio [OR], 0.3 [0.1-0.7]). General emergency physicians were 2.6 times more likely to use H2 antagonists and more than 3 times as likely to use corticosteroids. Only 14.2% of physicians overall were familiar with guideline recommendations.

CONCLUSIONS

Minimal awareness and use of existing guidelines, and low concordance with published recommendations exist. Management practices vary and are influenced by training, practice setting, and clinical experience.

Ultraviolet light phototherapy for allergic rhinitis

Phototherapy has a profound immunosuppressive effect and is widely used for the treatment of immune mediated skin diseases. Phototherapy is able to inhibit immediate type hypersensitivity reaction in the skin. Intranasal phototherapy is a new approach for treatment of allergic rhinitis. In two open studies, 308 nm excimer laser and topical PUVA therapy efficiently inhibited clinical symptoms of allergic rhinitis. In a randomized, double-blind study combined low dose UVB, low dose UVA and visible light proved to be effective in reducing symptom scores for sneezing, rhinorrhea, nasal itching and the total nasal score in ragweed allergic patients. Mechanism of action of phototherapy is complex, it reduces the antigen presenting capacity of dendritic cells, induces apoptosis of immune cells and inhibits synthesis and release of pro-inflammatory mediator from several cell types. Therefore, intranasal phototherapy may represent an alternative treatment of allergic rhinitis and other inflammatory and immune mediated mucosal diseases.

A fishy cause of sudden near fatal hypotension

Seafood-borne illnesses are a common but under recognised source of morbidity. We report the case of an 80-year-old woman who presented to hospital after collapsing in a restaurant following lunch consisting of mackerel fish. A detailed food history and clinical exclusion helped diagnose the condition as scombroid poisoning. The patient made a complete recovery following antihistamine therapy.

The histamine H4 receptor in autoimmune disease

Histamine exerts its actions through four known receptors. The recently cloned histamine receptor, H4R, has been shown to have a role in chemotaxis and mediator release in various types of immune cells including mast cells, eosinophils, dendritic cells and T cells. H4R antagonists have been shown to have anti-inflammatory properties and efficacy in a number of disease models, such as those for asthma and colitis in vivo. Recently, H4R antagonists have been developed with high receptor affinity and specificity, which make them good tools for further characterisation of the receptor in animal models and, eventually, in humans. Histamine and the cells that produce it, such as mast cells and basophils, have long been thought to be involved in allergic conditions but there has recently been recognition that they may also play a role in various autoimmune diseases. Given this and the fact that the H4R has function in mast cells, dendritic cells and T cells, antagonists for the receptor may be useful in treating autoimmune diseases in addition to allergy.

Levocetirizine improves health-related quality of life and health status in persistent allergic rhinitis

BACKGROUND

Allergic rhinitis is a chronic respiratory disorder with a detrimental impact on health-related quality of life (HRQOL) and health status. Enhancement and maintenance of patient function and well-being are therefore considered as essential.

OBJECTIVE

To determine whether long-term treatment with levocetirizine 5mg improves HRQOL and health status in persistent allergic rhinitis (PER) patients assessed with RQLQ and SF-36 scales over a 6-month period.

METHODS

The Xyzal in PER Trial (XPERT) was a multi-center, double-blind, parallel-group study. A total of 551 patients were randomized to receive levocetirizine 5mg or placebo once daily for 6 months and assessed for symptoms, HRQOL (Rhinoconjunctivitis Quality of Life Questionnaire: RQLQ) and health status (SF-36). Sensitivity of the RQLQ and SF-36 to disease severity was tested to ensure their suitability for use in PER patients. Treatment effect was assessed by means of repeated measures analyses.

RESULTS

Over the 6-month treatment period, levocetirizine showed statistically significant improvements over placebo in HRQOL (P < 0.001 for all RQLQ domains and overall scores) and health status (P < or = 0.004 for SF-36 physical and mental summary scores; P < 0.05 for all SF-36 scales). The relative improvement of levocetirizine over placebo exceeded the predefined clinically meaningful threshold of 30% for all RQLQ scores and the improvement from baseline was 3 times the established MID for RQLQ.

CONCLUSION

The RQLQ and SF-36 could be used to measure HRQOL and health status in PER patients. Long-term treatment with levocetirizine provides sustained improvement of HRQOL and reduces disease burden in PER patients.

Biomimetic hydrogels for enhanced loading and extended release of ocular therapeutics

We have applied the principles of biomimesis by incorporating a natural receptor-based rational design strategy in the synthesis of novel recognitive soft contact lenses. We have demonstrated the potential of biomimetic carriers to load significant amounts of ocular medication such as H(1)-antihistamines, as well as to release a therapeutic dosage of drug in vitro in a controlled fashion for 5 days, with an even further extension in the presence of protein. Gels of multiple complexation points with varying functionalities outperformed gels formed with less diverse functional monomers and showed superior loading with a six-fold difference over control gels and a three-fold difference over less biomimetic gels. Moreover, mechanical and optical properties of these hydrogels agreed with conventional lenses, and increased loading was reflected in a reduced propagation of polymer chains. This approach can be extended to a wider biological spectrum in the design of novel, controlled and modulated delivery devices to alleviate ocular disorders and provide an alternative to topical therapy.

Effect of levocetirizine on the contraction induced by histamine on isolated rabbit bronchioles from precision-cut lung slices

The present experiments were designed to study the effects of levocetirizine (a potent selective histamine H(1) antagonist) on the contraction induced by histamine on isolated rabbit bronchioles using the precision-cut lung slice technology. Histamine induced a concentration-dependent contraction of isolated rabbit bronchioles (pD(2) value of 5.6). Mepyramine (0.01-1 micromol/l) induced a shift to the right without any decrease in the concentration-response curve to histamine (pA(2) value of 8.2). Levocetirizine (0.03-0.1 micromol/l) induced both a shift to the right and a decrease in the maximal amplitude of the concentration-response curve to histamine (pA(2) and pD'(2) values of 7.9 and 7.0, respectively). The difference between both compounds could be explained in terms of the difference in the dissociation rate from the histamine H(1) receptor coupled to a putative low receptor reserve present in the rabbit bronchioles.

Efficacy and central nervous system impairment of newer-generation prescription antihistamines in seasonal allergic rhinitis

Allergic rhinitis is a highly prevalent disorder and oral antihistamines are often used to manage patient symptoms. Older-generation antihistamines, such as diphenhydramine and chlorpheniramine, are effective at relieving the symptoms of seasonal allergic rhinitis (SAR); however, they are associated with adverse events, including sedation and impairment, at, or above, the recommended dose. Newer-generation antihistamines, such as desloratadine, cetirizine and fexofenadine, were developed to minimize adverse events. In this article, studies examining newer-generation antihistamines in adults and children were reviewed. The clinical evidence confirms that desloratadine, cetirizine and fexofenadine are effective at managing the symptoms of SAR in adults and children; however, cetirizine is more likely to cause sedation. Physician intervention is paramount to SAR symptom management. It is essential that appropriate treatment relieves SAR symptoms with absent or minimal adverse events. This is particularly important for those patients involved in skilled and cognitive activities or safety-critical jobs.

Antihistamines and their role as antipruritics

Antihistamines that bind to the histamine 1 receptor (H1) serve as important therapeutic agents to counter the effects of histamine in the skin. Two generations of antihistamines exist; however, second-generation agents are more advantageous because they cause less sedation, have a longer half life and are more selective for the H1 receptor. While H1 antihistamines have proven to be effective at reversing the pruritus and cutaneous lesions of chronic urticaria, their ability to treat pruritus associated with other cutaneous and systemic diseases is unproven.

Keynote review: in vitro safety pharmacology profiling: an essential tool for successful drug development

Broad-scale in vitro pharmacology profiling of new chemical entities during early phases of drug discovery has recently become an essential tool to predict clinical adverse effects. Modern, relatively inexpensive assay technologies and rapidly expanding knowledge about G-protein coupled receptors, nuclear receptors, ion channels and enzymes have made it possible to implement a large number of assays addressing possible clinical liabilities. Together with other in vitro assays focusing on toxicology and bioavailability, they provide a powerful tool to aid drug development. In this article, we review the development of this tool for drug discovery, its appropriate use and predictive value.

Suppression of matrix metalloproteinase production in nasal fibroblasts by tranilast, an antiallergic agent, in vitro

Allergic rhinitis is an inflammatory disease characterized by nasal wall remodeling with intense infiltration of eosinophils and mast cells/basophils. Matrix metalloproteinases (MMPs), MMP-2 and MMP-9, are the major proteolytic enzymes that induce airway remodeling. These enzymes are also important in the migration of inflammatory cells through basement membrane components. We evaluated whether tranilast (TR) could inhibit MMP production from nasal fibroblasts in response to tumor necrosis factor-alpha (TNF-alpha) stimulation in vitro. Nasal fibroblasts (NF) were established from nasal polyp tissues taken from patients with allergic rhinitis. NF (2 x 10(5) cells/mL) were stimulated with TNF-alpha in the presence of various concentrations of TR. After 24 hours, the culture supernatants were obtained and assayed for MMP-2, MMP-9, TIMP-1, and TIMP-2 levels by ELISA. The influence of TR on mRNA expression of MMPs and TIMPs in cells cultured for 12 hours was also evaluated by RT-PCR. TR at more than 5 x 10(-5) M inhibited the production of MMP-2 and MMP-9 from NF in response to TNF-alpha stimulation, whereas TIMP-1 and TIMP-2 production was scarcely affected. TR also inhibited MMP mRNA expression in NF after TNF-alpha stimulation. The present data suggest that the attenuating effect of TR on MMP-2 and MMP-9 production from NF induced by inflammatory stimulation may underlie the therapeutic mode of action of the agent in patients with allergic diseases, including allergic rhinitis.

Changes in pH differently affect the binding properties of histamine H1 receptor antagonists

We investigated the effect of acidic pH, a condition that can be encountered during inflammation accompanying allergic reaction, on the binding properties of histamine H1 receptor antagonists, including levocetirizine ((2-(4-[(R)-(4-chlorophenyl)(phenyl)methyl]piperazin-1-yl)ethoxy)acetic acid; Xyzal ), fexofenadine (rac-2-[4-[1-Hydroxy-4-[4-(hydroxydiphenylmethyl) piperidin-1-yl]butyl]phenyl]-2-methylpropionic acid hydrochloride; Allegra) and desloratadine (8-Chloro-6,11-dihydro-11-(4-piperidylidene)-5H-benzo[5,6]cyclohepta[1,2-b]pyridine; Clarinex ). Lowering the pH from 7.4 to 5.8 decreased the affinity of [3H]mepyramine for histamine H1 receptors from 1.7 to 7.5 nM while the opposite was observed with [3H]levocetirizine, whose affinity increased from 4.1 to 1.5 nM. Competition curves with [3H]mepyramine indicated that decreasing the pH from 7.4 to 5.8 led to a 2- to 5-fold increase in the affinity of fexofenadine and levocetirizine, no change in affinity for desloratadine and a 5- to 10-fold decrease in affinity for mepyramine and histamine. Kinetic experiments showed that the increase in affinity of levocetirizine and, to a lesser extent, fexofenadine were totally attributable to a lower dissociation rate at acidic pH (t1/2 increasing from 77 to 266 min and from 71 to 135 min, respectively). Although the affinity of desloratadine remained unchanged, lowering the pH caused a decrease in its dissociation rate (t1/2 of 50 and 256 min at pH 7.5 and 5.8, respectively) accompanied by a concomitant 3.5-fold decrease in its association rate constant. The loss of affinity of mepyramine at acidic pH was driven by a decrease in its association rate constant. Interaction between the carboxylic moiety of levocetirizine and Lys191 is responsible for its slow dissociation rate from the receptor. We found that the magnitude of the pH effect on the dissociation rate of levocetirizine was maintained after mutating Lys191 into alanine, suggesting that a tighter interaction of levocetirizine with Lys191 at lower pH is not the cause of its even slower dissociation rate from the receptor. Although these changes may seem limited in amplitude, we show that they may have substantial effects on receptor occupancy in vivo.

Rhinophototherapy: a new therapeutic tool for the management of allergic rhinitis

BACKGROUND

Phototherapy has a profound immunosuppressive effect and is able to inhibit hypersensibility reactions in the skin.

OBJECTIVE

We evaluated whether phototherapy using a combination of UV-B (5%), UV-A (25%), and visible light (70%), referred to as mUV/VIS, is effective in treating allergic rhinitis.

METHODS

We conducted a randomized, double-blind study, in 49 patients with hay fever. The study was performed during the ragweed season. Each intranasal cavity was illuminated 3 times a week for 3 weeks with mUV/VIS or with low-intensity visible light. Symptom scores, inflammatory cells, and their mediators were assessed in nasal lavages. In vitro effects of mUV/VIS irradiation on T-cell and eosinophil apoptosis and its inhibitory effect on mediator release from basophils were examined.

RESULTS

Rhinophototherapy was tolerated well and resulted in a significant improvement of clinical symptoms for sneezing (P < .016), rhinorrhea (P < .007), nasal itching (P < .014), and total nasal score (P < .004). None of the scores improved significantly in the control group. Scores for nasal obstruction slightly improved after mUV/VIS treatment and significantly increased in the control group (P < .017). In the nasal lavage, phototherapy significantly reduced the number of eosinophils and the level of eosinophil cationic protein and IL-5. In vitro irradiation of T cells and eosinophils with mUV/VIS light dose-dependently induced apoptosis. Furthermore, mUV/VIS irradiation inhibited the mediator release from RBL-2H3 basophils.

CONCLUSION

These results suggest that phototherapy is an effective modality to treat allergic rhinitis and offer new options for the treatment of immune-mediated mucosal diseases.

Chemical genetic identification of the histamine H1 receptor as a stimulator of insulin-induced adipogenesis

A large collection of bioactive compounds with diverse biological effects can be used as probes to elucidate new biological mechanisms that influence a particular cellular process. Here we analyze the effects of 880 well-known small-molecule bioactives or drugs on the insulin-induced adipogenesis of 3T3-L1 fibroblasts, a cell-culture model of fat cell differentiation. Our screen identified 86 compounds as modulators of the adipogenic differentiation of 3T3-L1 cells. Examination of their chemical and pharmacological information revealed that antihistamine drugs with distinct chemical scaffolds inhibit differentiation. Histamine H1 receptor is expressed in 3T3-L1 cells, and its knockdown by small interfering RNA impaired the insulin-induced adipogenic differentiation. Histamine receptors and histamine-like biogenic amines may play a role in inducing adipogenesis in response to insulin.