The Effect of the Co-administration of Imipramine and Chlorpromazine on the Pharmacodynamics of Hydroxyzine in Rabbits

Short Communication


Fatma Naas¹ , Aisha Dugani ¹, Aisha Drah ², Rabea Musrati ³, Mabrouk Mohamed ¹, Sliman Gargeet¹

1-Department of Pharmacology, Faculty of Pharmacy 2-Department of Pharmacology, Faculty of medicine 3-Department of Biochemistry, Faculty of Pharmacy Al-Fateh University, Tripoli, Libya

JMJ 2009,Vol.9, No.1:65-67


H1-receptor antagonists such as hydroxyzine are commonly used to treat allergic dermatitis. However, it has been found that combination of H1-receptor antagonists with antipsychotic drugs such as chlorpromazine or imipramine enhanced their therapeutic efficacy. This could be explained by the additive antihistaminic effect of these two drugs. The administration of hydroxyzine caused a marked suppression of histamine-induced weal in rabbits. The co-administration of chlorpromazine or imipramine with hydroxyzine resulted in a significant increase in the suppression of histamine-induced weal as compared with hydroxyzine alone. However, the potentiation effect of imipramine was more pronounced than that of chlorpromazine. These results suggest that the enhancing effect of chlorpromazine or imipramine on the antihistaminic efficacy of hydroxyzine is due to the additive antihistaminic property of these two drugs.

Keywords: Histamine, H1-receptors, Anti-histaminic activity, Chlorpromazine, Imipramine, Potentiation.