title: [Antihistamines for the treatment of urticaria in Mexico].
abstract: There are four types of histamine receptors. Allergic symptoms, especially those in rhinoconjunctivitis and urticaria, are mainly caused by activation of histamine receptor 1 (H1). Consequently, oral H1-antihistamines form and integral part of the treatment of these diseases. Antihistamines are inverse agonists that stabilize the non-active configuration of the histamine receptor. First generation H1-antihistamines cause a variety of adverse effects via several mechanisms: sedation (accumulation in the central nervous system), dry mouth, urinary retention, weight gain (low selectivity: stimulation of serotonin/muscarinic/alpha-adrenergic receptors) and drug interactions (substrate of CYP450-3A4). Generally second generation H1-antihistamines have a better safety profile. New guidelines on allergic rhinitis and urticaria recommend second generation H1-antihistamines as first line drugs, with -if necessary- four-times updosing to obtain control in urticaria. The enhanced efficacy of quadruple doses in urticaria, while maintaining a good safety profile, has been shown for bilastine, desloratadine and levocetirizine (rupatadine). For ebastine and fexofenadine only the safety of quadruple doses has been shown till now. Extreme precaution should be taken with astemizol and terfenadine that never should be up-dosed, as high serum concentrations can cause potentially fatal ventricular tachycardia. First generation antihistamines are not recommended as first line treatment and updosing is not safe.
authors.affiliation: Clínica de Alergia, Asma y Pediatría del Sur, Hospital Médica Sur, Distrito Federal, México. marlar1@prodigy.net.mx.
authors.forename: Désirée
authors.initials: D
authors.lastname: Larenas-Linnemann
authors.forename: Mario
authors.initials: M
authors.lastname: Sánchez-Borges
authors.forename: Blanca Estela
authors.initials: BE
authors.lastname: Del Río-Navarro
authors.forename: María De Lourdes
authors.initials: Mde L
authors.lastname: Alonzo-Romero Pareyón
authors.forename: César Alfonso
authors.initials: CA
authors.lastname: Maldonado-García
authors.forename: Enrique
authors.initials: E
authors.lastname: Mendoza-López
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Ortega-Martell
authors.forename: Juan José Luis
authors.initials: JJ
authors.lastname: Sienra-Monge
authors.forename: Miguel Alejandro
authors.initials: MA
authors.lastname: Medina-Ávalos
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Rojo-Gutiérrez
authors.forename: Angélica María
authors.initials: AM
authors.lastname: Beirana-Palencia
authors.forename: Jorge Bernardo
authors.initials: JB
authors.lastname: Vargas-Correa
authors.forename: Carlos
authors.initials: C
authors.lastname: Báez-Loyola
authors.forename: Ruth Ivonne Mireya
authors.initials: RI
authors.lastname: Ramírez-Segura
authors.forename: María Graciela
authors.initials: MG
authors.lastname: Guzmán-Perea
keywords: allergic rhinitis; cytochrome P450; first generation antihistamines; second generation antihistamines; sedation; urticaria