Determination of the alpha,beta-adrenoceptor blocker YM-09538 in plasma by high-performance liquid chromatography with fluorescence detection

A high-performance liquid chromatographic method for the determination of the alpha,beta-adrenoceptor blocker 5-(1-hydroxy-2-[2-(o-methoxyphenoxy)ethylamino]ethyl]-2-methyl-benzenesulphonamide hydrochloride (YM-09538) in plasma, using 5-di-n-butylaminonaphthalene-1-sulphonyl chloride as a reagent for fluorescence labelling is described. The detection limit is 20 ng/ml, which is sensitive enough to determine YM-09538 plasma levels after the oral administration of effective doses to dogs and human.