vardenafil-dihydrochloride and acetonitrile

This work proposes a liquid chromatography-electrospray ionization ion trap mass spectrometry (LC-ESI-ITMS) method, for the quantification of sildenafil (SDF), tadalafil (TDF) and vardenafil (VDF) and their metabolites N-desmethylSDF, O-desethylSDF and N-desethylVDF, preceded by a sample preparation step based on protein and phospholipid elimination. A C8 column (150 mm × 4.6 mm, 5 μm) with ammonium formate (20mM) and acetonitrile as the mobile phase components have been used. This method has been validated, obtaining limits of quantification ranged from 1 to 2.5 ng/mL and 2 to 5 ng/g in serum and brain tissue respectively, while limits of detection ranged from 0.3 to 0.9 ng/mL in serum and 0.6 to 1.9 ng/g in brain tissue. Assay recoveries for low level QC samples were higher than 83% and the matrix effect ranged between 91% and 108% in serum and between 98% and 107% in brain tissue. The method has been applied to the quantification of these compounds in the serum and brain tissue of rats treated intraperitoneally with 10 mg/kg of SDF, TDF or VDF.

Topics: Acetonitriles; Animals; Biotransformation; Brain; Calibration; Carbolines; Chromatography, Liquid; Dealkylation; Formates; Imidazoles; Injections, Intraperitoneal; Limit of Detection; Male; Phosphodiesterase 5 Inhibitors; Piperazines; Purines; Rats; Rats, Sprague-Dawley; Reference Standards; Reproducibility of Results; Sensitivity and Specificity; Sildenafil Citrate; Spectrometry, Mass, Electrospray Ionization; Sulfones; Tadalafil; Tandem Mass Spectrometry; Triazines; Vardenafil Dihydrochloride