Detection of landiolol using high-performance liquid chromatography/fluorescence: A blood esterase- sensitive ultra-short-acting [beta][sub]1-receptor antagonist

Landiolol hydrochloride, a new adrenergic [beta][sub]1-selective antagonist having an ultra-short half- life, is used to prevent tachyarrhythmia during surgery. Since landiolol is thought to be rapidly hydrolyzed to an inactivate metabolite by esterases, quantification of the drug concentration in the blood is impractical. The landiolol concentration in blood was halved within 5 min after blood sampling. This degradation was effectively prevented by pre-treatment with neostigmine (100 [micro]g) in the sampling tube, but not by EDTA pre-treatment, indicating that landiolol could be metabolized by pseudocholinesterase in plasma. After the one-step solid-phase extraction, fluorescence detection of landiolol reduced chromatographic background signals and then improved assay sensitivity to the lower limit of 10 ng/ml in blood; this reproducible approach yielded coefficient variation of less than 6%. The blood concentration- time profile of landiolol hydrochloride in patients of the present investigation afforded more practical assessment than previously reported studies, thus improving accuracy and facilitating detailed pharmacokinetic study in relation to the pharmacological action of drug.