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Interactions of the H1 antihistamines


J Bartra 1, AL Valero 1, A del Cuvillo 2, I Dávila 3, I Jáuregui 4, J Montoro 5, J Mullol 6, J Sastre 7

1 Unitat d’Al·lèrgia. Servei de Pneumologia i Al·lèrgia Respiratòria. Hospital Clínic (ICT). Barcelona, Spain;
2 Clínica Dr. Lobatón. Cádiz, Spain;
3 Servicio de Alergia. Hospital Clínico. Salamanca, Spain;
4 Unidad de Alergología. Hospital de Basurto. Bilbao, Spain;
5 Unidad de Alergia. Hospital La Plana. Villarreal (Castellón), Spain;
6 Unitat de Rinologia, Servei d’Otorinolaringologia (ICEMEQ). Hospital Clínic. Barcelona, Spain;
7 Servicio de Alergia. Fundación Jiménez Díaz. Madrid, Spain

J Investig Allergol Clin Immunol 2006; Vol. 16, Supplement 1: 29-36



An interaction is taken to be the situation in which the administration of a drug or substance induces changes in the pharmacokinetics of another simultaneously administered drug – either increasing or decreasing the plasma concentration of the latter, and thus giving rise to the possibility of adverse reactions [1].
According to the primarily responsible pharmacological mechanism, H1 antihistamine interactions are fundamentally of a pharmacokinetic nature: the triggering drug or substance induces changes in the absorption and/ or metabolism of the H1 antihistamine [2]. Interactions of a pharmacodynamic nature, i.e., corresponding to those
situations in which the actions of the drug or substance upon its target tissues induce modifi cations in the actions of another drug, have not been reported to date.
The interactions described to date between the H1 antihistamines and other drugs or substances fundamentally take place via three different routes: the P450 cytochrome system; P glycoprotein (PgP); and the members of the organic anion transport polypeptide (OATP) family.. .../... more at PDF full text