Determination of a novel antiarrhythmic agent ACC-9358 in human plasma by high-performance liquid chromatography

A liquid chromatographic method for the determination of ACC-9358, an antiarrhythmic agent, in human plasma is described. ACC-9358 was extracted from plasma into chloroform and back extracted into 0.01 N hydrochloric acid. ACC-9358 in the acidic extract was eluted from a Novapak C18 column using a 87:13:0.1 (by volume) mixture of phosphate buffer (pH 3.0), acetonitrile, and triethylamine as the mobile phase and measured at 280 nm. The average extraction recoveries were 78.4 and 85.4% at the 0.5- and 5-micrograms/ml level, respectively. Standard curves were linear and reproducible over the concentration range of 0.01-10 micrograms/ml, with coefficients of determination better than 0.999. Coefficients of variation for both within-day and day-to-day analysis were less than 11%. The assay method is sensitive, reproducible, and suitable for disposition studies of ACC-9358 in humans.