Imoxiterol (also known as RP 58802B) is benzimidazole derivatives patented by pharmaceutical company Laboratoire Roger Bellon S. A as a long-acting β-adrenergic agonist. In preclinical models, nebulized Imoxiterol produced a rapid onset and long-lasting inhibition of histamine-induced bronchospasm in the anaesthetized guinea-pig. Given orally, Imoxiterol produced a greater than three-fold shift to the right of the dose-response curve and depressed the maximum response to histamine. Imoxiterol prevented the development of bronchial hyperreactivity. Although PAF-induced bronchial hyperreactivity was not accompanied by an increase in the number of pulmonary eosinophils, Imoxiterol reduced the numbers of eosinophils recovered by lavage. Imoxiterol significantly inhibited PAF-induced microvascular leakage into guinea-pigs lung.