Antihistaminic effects of Azadirachta indica leaves in laboratory animals

Azadirachta indica (Meliaceae) leaves have been traditionally used in the management of asthma and the current study was undertaken to scientifically validate the benefits of plant as an antihistaminic agent using the suitable animal model. The agents with antihistaminic properties are known to be good antiasthmatic agents; hence, in the current research work, the antihistaminic activity of an ethanolic extract of Azadirachta indica leaves (at a dose of 250 mg/kg, i.p.) was evaluated using haloperidol-induced catalepsy and clonidine-induced catalepsy in laboratory rats. The results showed that the ethanolic extract inhibits the catalepsy induced by the clonidine but no remarkable effect was observed on the catalepsy induced by haloperidol. This strongly suggests that, the inhibition is mediated through an antihistaminic action and there is no role of dopamine. Hence, in the present study, it is concluded that, the ethanolic extract has significant antihistaminic activity. The polar constituents in the ethanolic extract of leaves of Azadirachta indica may be responsible for the antihistaminic effects and therefore, the ethanolic leaves extract can be a better remedy as an antihistaminic agent.