RESUMO
Loratadine [Claritine] is a new antihistaminic drug that blocks the peripheral H1-receptors. This study was conducted to speculate whether it may possess other properties than merely being an antagonist at the H1-receptors. Its effect on mast cells stabilization and mediator release was investigated both pharmacologically and histologically. The pharmacological part comprised the study of the histamine induced contraction of the isolated guinea pig trachea obtained from three groups of animals [the control group, the sensitized challenged group and the sensitized challenged loratadine-treated group receiving the drug orally daily for 3 weeks before anaphylaxis]. The histological part comprised demonstrating mast cells in the three groups in the connective tissue, trachea and lung. The percentage of degranulated cells in the connective tissue was calculated in each group. The results obtained from both studies a mast cell stabilizing effect and inhibition of mediator release which may contribute to its anti-allergic effect especially in patients with bronchial asthma