“…Actual plasma concentration of parent drug with metabolites is of therapeutic importance, although the prodrug is not active. Numerous methods are available for detection of ASA with its active metabolite salicylic acid (SA) (Altamura et al , ; Bae et al , ; McMahon and Kelly, ; Mullangi et al , ; Pirker et al , ; Shaw and Tsai, ; Yamamoto et al , ). Similarly, various methods are available for determination of CLP and CLPM (Delavenne et al , , ; El‐Sadek et al , ; Karaźniewicz‐Łada et al , ; Peer et al , ; Robinson et al , ; Silvestro et al , ; Singh et al , ; Souri et al , ; Yang et al , ) However, owing to rapid and extensive metabolism, ASA and CLP were found at very low concentration in plasma (pg/mL).…”