High-performance liquid chromatographic determination of BRB-I-28, a novel antiarrhythmic agent, in dog plasma and urine.

A sensitive reversed-phase high-performance liquid chromatographic (HPLC) technique with ultraviolet detection has been developed to determine the concentration of BRB-I-28 (I), a novel antiarrhythmic agent, in dog plasma and urine. The mobile phase was acetonitrile-methanol-37.5 mM phosphate buffer, pH 6.8-triethylamine (50:50:75:0.1, v/v). The compound was extracted from dog plasma and urine with chloroform after alkalinization with sodium hydroxide. The extraction recovery was 83% from plasma and 84% from urine. Good linearity (r > 0.996) was observed throughout the ranges 0.1-12.0 micrograms/ml (plasma) and 0.1-8.0 micrograms/ml (urine). Intra- and inter-assay variabilities were less than 4%. The lower limit of quantitation was 0.08 microgram/ml in either plasma or urine. HPLC analysis of plasma and urine samples from a dog treated with I has demonstrated that the method was accurate and reproducible.