Validation of an LC–ESI-MS/MS method for the quantitation of phosphodiesterase-5 inhibitors and their main metabolites in rat serum and brain tissue samples

Validated spectrofluorimetric method for determination of two phosphodiesterase inhibitors tadalafil and vardenafil in pharmaceutical preparations and spiked human plasma

“…Reviewing the literature revealed that several methods have been described for determination of both TAD and VAR either in pharmaceutical preparations or in biological fluids. Regarding TAD, the following methods have been reported including: spectrophotometry , densitometry , high‐performance liquid chromatography (HPLC) , liquid chromatography‐tandem mass spectrometry (LC/MS/MS) , gas chromatography–mass spectrometry (GC‐MS) , using adsorptive stripping square wave voltammetry , and micellar electrokinetic capillary chromatography (MEKC) . Meanwhile, VAR was determined via different analytical procedures including: HPLC , LC/MS/MS , GC‐MS , electrochemical method , CE , and MEKC .…”

Quantitation of tadalafil in human plasma using a sensitive and rapid LC-MS/MS method for a bioequivalence study

“…Though currently there are several methods to determine TAD in different biological matrices, the aim of the present work was to develop a highly sensitive and rapid method to meet the requirement of pharmacokinetic studies in healthy humans. All existing chromatographic methods have a limit of quantitation (LOQ), ≥ 2.0 ng/mL except one report in rat serum which reports LOQ of 1.0 ng/mL [17] . Further, only two methods [8] , [14] have a chromatographic analysis time of less than 5.0 min.…”

“…Mass spectrometer parameters were optimized by infusing 500 ng/mL solution of TAD and TAD-d3 in the positive ESI mode as reported previously [8] , [13] , [17] . The infusion was performed directly in the ionization source at a flow of 10 mL/min.…”

“…Several bioanalytical methods are available in the literature for the determination of TAD as a single analyte [8] , [9] , [10] , [11] , [12] , [13] , [14] , and with other PDE-5 inhibitors [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] in different biological samples like rat plasma [9] , [14] , rat serum and brain tissue [17] , mouse plasma [11] , human and rat hair [20] , human whole blood [12] , [18] , seminal plasma [13] , human urine [15] , [22] and human plasma [8] , [10] , [13] , [16] , [19] , [21] , [23] . Varieties of analytical techniques have been employed for its estimation including spectrofluorometry [21] , gas chromatography-mass spectrometry (GC-MS) [12] , [15] , high performance liquid chromatography-ultraviolet (HPLC-UV) [9] , [10] , HPLC-fluorescence [11] , liquid chromatography-tandem mass spectrometry (LC-MS/MS) [8] , [13] , [14] , [16] , [17] , [19] , [20] , [22] , [23] and ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) [18] . A comparative summary of chromatographic methods developed for TAD in different biological samples is shown in Table S1 .…”

“…A comparative summary of chromatographic methods developed for TAD in different biological samples is shown in Table S1 . Majority of these methods have either low sensitivity (≥ 5.0 ng/mL) [8] , [9] , [10] , [11] , [15] , [16] , [18] , long analysis time (> 5.0 min) [9] , [10] , [11] , [12] , [15] , [16] , [17] , [18] , [20] , [22] , [23] or require large sample volume for processing (≥ 500 µL) [10] , [12] , [15] , [16] , [18] , [22] . Thus, it is essential to develop a highly sensitive, selective and rapid bioanalytical assay especially to meet the requirement of pharmacokinetic studies.…”