Simultaneous LC-UV analysis of mirodenafil and its two main metabolites in rat plasma and urine, and in tissue homogenates

A simple, rapid, and reproducible isocratic reversed-phase LC method has been established for simultaneous analysis of mirodenafil and its two main metabolites, SK3541 and SK3544, in rat plasma, urine, and tissue homogenates. Samples were deproteinized with acetonitrile containing sildenafil (internal standard). The compounds were separated on a C₁₈ column with 52:48 (v/v) 0.02 m ammonium acetate buffer (pH 6)-acetonitrile as mobile phase at a flow rate of 1.4 mL min^-1. UV detection was at 254 nm and detection limits of mirodenafil, SK3541, and SK3544 in plasma were 0.03, 0.05, and 0.1 μg mL^-1, respectively. The method is applicable to pharmacokinetic studies of mirodenafil and its metabolites in rats.