New antihistamines: a critical view

Abstract

Objective: To perform a critical evaluation of the more recent H1 antihistamines and the various terms used to describe them, based on a review of evidence on their role in the treatment of allergic disorders.Sources: Original articles, reviews and consensus documents published from 1998 to 2006 and indexed in the MEDLINE and PubMed databases. Keyword: antihistamines.Summary of the findings: 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 of the central nervous system (CNS), having fewer sedative effects as a result. Whilst second-generation antihistamines are in general better tolerated than their predecessors, some adverse effects, principally cardiotoxicity, have been observed with some of them. Over the last 20 years, new compounds with different pharmacokinetic properties have been synthesized. The majority of these exhibit antiinflammatory properties that are independent of their action on the H1 receptor. More recent improvements, generally in the form of active metabolites, led to the use of the term third-generation antihistamines. This term emerged spontaneously, with no clear definition of its meaning or clinical implications, creating great confusion among healthcare professionals. Conclusions:On the basis of the evidence on H1 antihistamines, none of them deserve the title third-generation antihistamine. As the Consensus Group on New Generation Antihistamines concluded, to merit this definition, a new class of antihistamines would have to demonstrate distinct clinical advantages over existing compounds and fulfill at least three prerequisites: they should be free from cardiotoxicity, drug interactions and effects on the CNS. J Pediatr (Rio J). 2006;82(5 Suppl):S173-80: Antihistamines, desloratadine, fexofenadine, levocetirizine, rupatadine. ResumoObjetivo: Avaliar criticamente os mais novos anti-histamínicos anti-H1 e os diferentes termos utilizados para denominá-los, com base na revisão de evidências sobre o papel dos anti-H1 no tratamento das doenças alérgicas.Fontes dos dados: Artigos originais, revisões e consensos indexados nos bancos de dados MEDLINE e PUBMED de 1998 a 2006. Palavra chave: anti-histamínicos.

Abnormal Transient Pupillary Light Reflex in Individuals with Autism Spectrum Disorders

“…Therefore the accommodation-induced near pupil responses can be excluded as an influencing factor. A total of five participants took over-the-counter medications which may have certain influences on the central nervous system (Cantú and Korek 1991;Camelo-Nunes 2006). Although their effects on PLR are unstudied, all significant statistical findings remained the same when these participants were excluded from our analysis.…”

Desloratadine and depression, a drug safety signal based on worldwide spontaneous reporting of side effects

“…It is an active metabolite of loratadine and is indicated for the symptomatic treatment of allergic rhinitis and urticaria ( 1 ). Antihistamines prevent the occurrence of histamine-activated processes ( 3 ). They inhibit smooth muscle contraction in bronchi and the gastrointestinal tract and inhibit the capillary permeability and the stimulation of sensory nerves.…”

Designing, docking and molecular dynamics simulation studies of novel cloperastine analogues as anti-allergic agents: homology modeling and active site prediction for the human histamine H1 receptor

“…Terfenadine and astemizole were removed from the market due to serious cardiovascular events related to torsade de pointes. [10][11][12] Cloperastine is one of these drugs with different biological activities including GIRK channel inhibition, [13][14][15] antihistamine activity and anticholinergic activity. 16 Due to these properties, cloperastine shows some side effects such as sedation, somnolence and tussive effect.…”