GR 63411B

GR 63411B is the racemic form of picumeterol, a potent and selective β2-adrenoceptor agonist. It acts as a bronchodilator by stimulating β2-adrenoceptors in airway smooth muscle, leading to increased intracellular cyclic AMP (cAMP) and subsequent relaxation of bronchial smooth muscle. Clinical studies have shown that both picumeterol (the R-enantiomer) and GR 63411B exhibit similar bronchodilator potency but are short-acting when administered to asthmatic patients. Despite their ability to cause bronchodilation, neither drug significantly improved airway hyperresponsiveness compared with placebo. The dissociation between bronchodilator activity and protection against methacholine-induced bronchoconstriction may be due to low intrinsic activity[1].