Accurate and sensitive determination of sildenafil, tadalafil, vardenafil, and avanafil in illicit erectile dysfunction medications and human urine by LC with quadrupole‐TOF‐MS/MS and their behaviors in simulated gastric conditions

Abstract

The widespread use of phosphodiesterase‐5 inhibitors has attracted broad attention of counterfeiters to develop illicit erectile products with inaccurate amounts, unknown toxicity, and purity of active ingredients. Correspondingly, intake of these products endangers consumer health and needs to be screened for precautionary actions to reduce this risk. Therefore, in this study, a sensitive and rapid analytical method has been developed for simultaneous determination of selected phosphodiesterase‐5 inhibitors present in illicit erectile medications and human urine. Quantification of the analytes was performed by liquid chromatography coupled with quadrupole‐time‐of‐flight tandem mass spectrometry system. The chromatographic separation was successfully achieved with a run period of 8 min. Low detection limits were obtained in the range of 1.63–9.81 ng/g with relative standard deviations below 7.72% obtained using the replicate measurements of lowest concentration in calibration plots. The analytical performance of the proposed method proved good linearity, low detection limits, good accuracy and precision with high percent recoveries for human urine samples. Developed method was successfully applied to real samples including four different brands of illicit erectile medications. The results obtained revealed the presence of high levels of sildenafil in analyzed samples. The behaviors of selected phosphodiesterase‐5 inhibitors were also studied in simulated gastric conditions.

Isolation and yield optimization of lipopeptides from Bacillus subtilis Z‐14 active against wheat take‐all caused by Gaeumannomyces graminis var. tritici

“…MALDI‐TOF‐MS has many advantages for component identification including great convenience for the analysis of detected substances [17]. TOF‐MS analysis of the mass‐to‐charge ratio ( m/z ) often simply requires comparison with m/z values of substances already present in the database for identification [18].…”

Second derivative synchronous fluorescence determination of avanafil in the presence of its acid-induced degradation product aided by powerful Lean Six Sigma tools augmented with D-optimal design

“…Avanafil (99.48%), prepared using a reported method, 10 was supplied by Atco Pharma for Pharmaceutical Industries, Egypt.…”

“…[1][2][3][4][5] For the determination of avanal, the literature reveals that many methods have been reported for the quantitative estimation of the studied drug avanal including multivariate chemometric methods 6 and different chromatography techniques. [7][8][9][10][11][12] Fluorescence spectroscopy is associated with major advantages such as good selectivity, low detection limit and hence high sensitivity. Many drugs have been determined using this technique.…”

Multiplex optical bioassays for food safety analysis: Toward on‐site detection

“…Moreover, food samples usually contain more than one single contaminant, and may be contaminated by a number of structurally or effectively similar compounds. For instance, in the case of illicit erectile dysfunction functional foods, more than one phosphodiesterase‐5 inhibitor (PDE‐5 inhibitor) is usually adulterated (Öztürk et al., 2019; Vijayaraj et al., 2017). Therefore, multianalyte detection methods that respond to all the PDE‐5 inhibitors are useful and in demand.…”