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Concept: H1 antagonist


Background  Recently, the updated EAACI/GA(2) LEN/EDF/WAO guidelines for urticaria have been published. Objective  To examine how chronic spontaneous urticaria (csU) patients in Germany are diagnosed and treated, and to compare the outcome to the guideline recommendations. Methods  During this cross-sectional survey study, most dermatologists, paediatricians and 5149 general practitioners in private practice in Germany were asked to participate. All physicians who agreed were requested to complete a standardized questionnaire about their diagnostic and therapeutic management of csU. Results  A total of 776 questionnaires were available for analysis. Most physicians (82%) were attempting to identify underlying causes in their csU patients, but with only limited success. More than 70% reported to check for total serum IgE and to do skin prick testing (not suggested in first line by guideline). In contrast, only 10% applied the autologous serum skin test. The most common first-line treatments were non-sedating antihistamines in standard or higher doses (as recommended). However, many physicians reported still using first generation sedating antihistamines (23%) (not recommended) or systemic steroids (18%). Experience with alternative options was low. Less than one-third of the participants reported to be familiar with the guidelines. Those who did, were found to be more likely to check for underlying causes, to be more experienced with antihistamine updosing and to be more reluctant to use sedating antihistamines or systemic steroids. Conclusion  The diagnostic and therapeutic management of csU by private practice physicians does not sufficiently comply with the guidelines. Awareness of the guidelines can lead to improved care.

Concepts: Medicine, Physician, Histamine, General practitioner, Questionnaire, H1 antagonist, Histamine antagonist, Antihistamines


Introduction: Urticaria is a highly prevalent disease among people. First-choice treatment continues to be centred on the second-generation H1 antihistamines, including a wide group of drugs with a better therapeutic index (or risk:benefit ratio) than the classic ones, even in the high, off-label dosage occasionally required in chronic urticaria. Bilastine is a newly registered H1-antihistamine for treatment of allergic rhinoconjunctivitis and urticaria. With established antihistaminic and antiallergic properties, it is widely reviewed in the medical literature; however, to our knowledge, a specific review of bilastine’s role in the treatment of urticaria was lacking. Areas covered: This article reviews the medical literature on the effectiveness and safety of bilastine in urticarial syndromes, either spontaneous or inducible, by means of a Medline search from 1990 to present, completed with some nonpublished data provided by the manufacturer. Expert opinion: Once-daily treatment with bilastine 20 mg is effective in managing symptoms and improving patient’s quality of life in chronic urticaria, with at least comparable efficacy to levocetirizine. As far as studies in healthy volunteers, clinical assays, and recent clinical experience can establish, bilastine’s safety profile is adequate, appearing to be entirely free from cardiovascular effects, and not impairing psychomotor performance or actual driving, even at twice the therapeutic dose.

Concepts: Pharmacology, Medicine, Asthma, Effectiveness, Efficacy, Urticaria, H1 antagonist, Histamine antagonist


OBJECTIVE: Recent evidence indicates that antihistamines can affect movement, which is most likely due to altered neurotransmission in cholinergic and histaminergic pathways. The purpose of this study was to determine if antihistamines with varying anticholinergic properties differentially affect voluntary and involuntary movement control. METHODS: Eleven healthy subjects were enlisted into a human double blind, placebo-controlled, five-way crossover study. Drowsiness, reaction time, and physiological tremor were examined 1-, 2-, and 3-hr post-ingestion of antihistamines with known anticholinergic profiles. These were the first-generation promethazine, and second-generation loratadine, desloratadine, and fexofenadine. Hyoscine butylbromide was used in an additional experiment to determine how a peripheral antimuscarinic drug influenced neuromotor function. RESULTS: Promethazine, desloratadine and fexofenadine increased drowsiness. Promethazine increased simple and choice reaction time and reduced tremor. Desloratadine increased choice reaction time and tremor, while loratadine slowed simple and choice reaction time. CONCLUSION: Central anticholinergic and antihistaminergic properties of antihistamines potentially contribute to movement dysfunction. SIGNIFICANCE: Second-generation antihistamines have provided the consumer with a safer alternative to the first-generation sedating antihistamine. However, the results of this study suggest that loratadine and desloratadine have the potential to affect movement control, and further research is warranted to understand the clinical relevance of these findings.

Concepts: Crossover study, Histamine, Anticholinergic, H1 antagonist, Histamine antagonist, Antihistamines, H1 receptor antagonists, Scopolamine


Abstract Background: Levocetirizine and desloratadine are mostly used H1-antihistamines in the treatment of allergic disease in 5 mg and 10 mg doses. Objective: In this study, the efficacy of single oral dosages of 5 mg and 10 mg desloratadine and levocetirizine were compared by using histamine-induced wheal and flare reactions. Methods: Eighty healthy volunteers were randomized for 4 double blinded treatment with desloratadine 5 mg-10 mg, levocetirizine 5 mg-10 mg. Wheal and flare responses were produced by histamine. Measurements were performed just before the ingestion of antihistamines (baseline) and afterwards at 30, 60, 240 minutes and 24 hours. The values obtained for each antihistamine were compared with baseline values. Results: It was found that, except the flare reactions at 30th minute, levocetirizine 5 mg and 10 mg suppressed histamine-induced wheal-flare reactions more than desloratadine 5 mg and 10 mg did. There were not any significant differences between desloratadine 5 mg and 10 mg in all periods. Levocetirizine 10 mg suppressed wheal-flare reactions significantly more than levocetirizine 5 mg only at 24th hour. Conclusion: In this study it was observed that levocetirizin 5 mg and 10 mg has a higher activity than desloratadine’s.

Concepts: Allergy, Dose, Histamine, Harshad number, H1 antagonist, Histamine antagonist, Antihistamines


Research indicates that first-generation antihistamine usage may impair pilot performance by increasing the likelihood of vestibular illusions, spatial disorientation, and/or cognitive impairment. Second- and third-generation antihistamines generally have fewer impairing side effects and are approved for pilot use. We hypothesized that toxicological findings positive for second- and third-generation antihistamines are less likely to be associated with pilots involved in fatal mishaps than first-generation antihistamines.

Concepts: Regression analysis, Econometrics, Histamine, Poisson regression, H1 antagonist, Histamine antagonist, Aviator, Antihistamines


An increase in dosages up to fourfold of second generation antihistamines is recommended for recalcitrant chronic spontaneous urticaria (CSU). No regimen guidelines about dose de-escalation, however, are mentioned once the disease is controlled.

Concepts: Dose, H1 antagonist


Selective Serotonin Reuptake Inhibitors (SSRI) were a disqualifying medication for U.S. civil pilots before April 5, 2010. After this date, a Federal Aviation Administration policy was created that allowed airmen, on select SSRIs, a pathway to hold a valid medical certificate. The purpose of this study was to provide a detailed look at SSRIs in the U.S. pilot population since the inception of this new policy. We examined the toxicology results from fatally injured airmen in addition to outcomes concerning pilots who are participating in the program. This study examined data from the Civil Aerospace Medical Institute’s Bioaeronautical Sciences Research Laboratory in conjunction with the Medical Analysis Tracking Registry and the Document Imaging and Workflow System. A count-based regression model quantified the relationships between positive SSRI findings with additional factors of interest. These factors included pilot rating, ethanol, and first generation antihistamines. There were 1484 fatally injured airmen over the six year study period, of which 44-tested positive for an SSRI. First-generation antihistamines were statistically associated with positive findings of SSRIs.

Concepts: Serotonin, Antidepressant, Selective serotonin reuptake inhibitor, Major depressive disorder, Sertraline, Tricyclic antidepressant, Reuptake inhibitor, H1 antagonist


Following photodynamic therapy with 5-aminolevulinic acid (ALA-PDT), patients experience inflammation that may be partially attributable to H1 histamine receptor activation. The objective of this study was to evaluate the impact of antihistamines upon adverse effects following ALA-PDT.

Concepts: Immune system, Clinical trial, Effectiveness, Histamine, Placebo, H1 antagonist, Histamine antagonist, Histamine H1 receptor


Omalizumab is recombinant humanized monoclonal antibody to immunoglobulin E. Guidelines for the treatment of chronic idiopathic urticaria (also known as chronic spontaneous urticaria) recommend the use of omalizumab as third-line therapy in addition to high doses of histamine receptor type 1 (H1 ) antihistamines when they are unsuccessful as first- and second-line therapy. We performed a systematic review of the literature to identify studies that evaluated the efficacy of omalizumab for the treatment of chronic idiopathic urticaria, both in controlled and real-world settings, to assess its potential role as a preferred therapy. The PubMed, ScienceDirect, LILACS (Latin American and Caribbean Health Sciences Literature), and Google Scholar databases were searched between January 1, 2000 and November 21, 2016. The search was limited to articles published in peer-reviewed journals in the English language, and 29 studies were included in this review. Omalizumab 300 mg administered every 4 weeks appears to be the most effective and safe dosage, with a rapid response time, for the treatment of chronic idiopathic urticaria, with few minor adverse effects, and appears to be safe in the offspring of pregnant patients who received the drug. However, as published studies of omalizumab are sparse, future studies are warranted. When findings are confirmed in larger studies, due to its efficacy, safety, and increased benefit/cost ratio, omalizumab could become the preferred method of treatment for chronic idiopathic urticaria in patients unresponsive to H1 antihistamines. This article is protected by copyright. All rights reserved.

Concepts: Immune system, Medicine, Monoclonal antibodies, Academic publishing, Histamine, Urticaria, Copyright, H1 antagonist


The crystal structure of the human histamine H1 receptor (H1R) has been determined in complex with its inverse agonist doxepin, a first-generation antihistamine. The crystal structure showed that doxepin sits deeply inside the ligand-binding pocket and predominantly interacts with residues highly conserved among other aminergic receptors. This binding mode is considered to result in the low selectivity of the first-generation antihistamines for H1R. The crystal structure also revealed the mechanism of receptor inactivation by the inverse agonist doxepin. On the other hand, the crystal structure elucidated the anion-binding site near the extracellular portion of the receptor. This site consists of residues not conserved among other aminergic receptors, which are specific for H1R. Docking simulation and biochemical experimentation demonstrated that a carboxyl group on the second-generation antihistamines interacts with the anion-binding site. These results imply that the anion-binding site is a key site for the development of highly selective antihistamine drugs.

Concepts: Signal transduction, Histamine, Receptor antagonist, Agonist, Inverse agonist, H1 antagonist, Histamine antagonist, Histamine H1 receptor