Validated LC-MS/MS assay for the quantitative determination of vardenafil in human plasma and its application to a pharmacokinetic study

Liquid Chromatography-Tandem Mass Spectrometry Method for the Determination of Vardenafil and Its Application of Bioequivalence

A simple, rapid, and sensitive method of liquid chromatography-tandem mass spectrometry (LC/MS/MS) method was developed and validated for the determination of vardenafil in rabbit plasma. A simple protein precipitation method with ice-cold acetonitrile was used for plasma extraction. The mass transitions m/z 489⟶151 and m/z 390⟶169 were used to measure vardenafil and tadalafil (internal standard), respectively, with a total assay run time of 6 min. The limit of detection was 0.2 ng/mL. The assay was reproducible with intra-assay and interassay precision ranging 1.17%-9.17% and 1.31%-5.86%, respectively. There was also good intra-assay and interassay accuracy between 89.3%-105.3% and 94%-102% of the expected value, respectively. The linearity range was 0.5-60 ng/mL in rabbit plasma (r 2 ≥ 0.99). The measured AUC from 0 to 24 h (AUC0 - 24t ) for the test and reference formulations were 174.38 ± 95.91 and 176.45 ± 76.88, respectively. For the test, C max and T max were 75.36 ± 59.53 ng/mL and 1.42 ± 0.19 h, whereas, for the reference, these were 58.22 ± 36.11 ng/mL and 2.04 ± 0.33 h, respectively. The test formulation achieved a slightly lower AUC0 - 24t value (p > 0.05), higher C max values (p > 0.05), faster T max (p < 0.05), and almost equal bioavailability compared with the reference formulation.

Optimization of the Factors Affecting the Absorption of Vardenafil from Oral Disintegrating Tablets: A Clinical Pharmacokinetic Investigation

Because of poor solubility and considerable metabolism, vardenafil (VRD) bioavailability is 15%. To overcome this obstacle, this study aimed to increase the solubility, hasten the onset of action, and mask the unpleasant taste of VRD utilizing β-cyclodextrin (β-CD) and formulation of the inclusion complex as oral disintegrating tablets (ODTs). The solubility of the obtained complexes in various ratios has been studied. A Box–Behnken design (BBD) was utilized to investigate the influence of excipients on the quality of ODTs. The solubility of VRD was improved at 1:2 drug:β-CD ratio. The formulated VRD-ODTs exhibited satisfying results regarding the hardness and disintegration time. In addition, in vivo taste masking and disintegration time showed improved results, after placing the tablets in the oral cavity of the healthy volunteers. When compared with the marketed tablets, the pharmacokinetic parameters for the optimized VRD-ODTs exhibited a significant improvement with p < 0.05 in the maximum plasma concentration and reduction in the time needed to reach this concentration. Finally, the optimized VRD-ODTs exhibited increased oral absorption of VRD and subsequent decrease in the time of onset of clinical effect and masking the unpleasant taste.