Development of a detector tube for screening tadalafil and its analogues in adulterated sexual enhancement products.

Sexual enhancement products adulterated with phosphodiesterase 5 inhibitors (PDE-5i) pose a serious public health concern. Tadalafil and its analogues (Tds) are PDE-5i frequently detected as adulterants. In this study, a Td detector tube for the rapid detection of Tds was developed based on the color change reaction between sulfuric acid and Tds. The specificity of this test method was evaluated using 13 Tds, all of which elicited positive results. Additionally, 30 commonly found adulterants in dietary supplements, 11 active pharmaceutical ingredients of psychotropic drugs and 18 food ingredients were tested and obtained no false-positive results, except levomepromazine. The test tube accurately detected the presence or absence of Tds in 54 commercially available products. The visual detection limit was 2-50 and 5-20 µg/ml for Tds and tadalafil-spiked samples with matrix, respectively. The applicability of the developed detector tube to a semiquantitative test using digital image analyses were investigated using red, green, and blue color values. The results of the recovery test suggested that the tube test was affected by the dark-colored matrix. The results of semiquantitative analyses of tadalafil for five marketed products were consistent with the liquid chromatographic quantification results, except for the blue value. The detector tube developed in this study can facilitate with the rapid screening of Tds in adulterated sexual enhancement products.

[Identification of Descarbonsildenafil in an Adulterated Dietary Supplement and Evaluation of Its Inhibitory Activity for Phosphodiesterase Type 5 (PDE5)].

Some illegal dietary supplements contain phosphodiesterase type 5 (PDE5) inhibitors, such as sildenafil, for exerting "therapeutic" effects in erectile dysfunction. This is apparently dangerous, and thus, should be appropriately regulated. Identification of descarbonsildenafil was first reported in Singapore in a coffee sample labeled to exert male sexual performance enhancement effects. However, it is unclear whether the compound possesses PDE5 inhibitory activity. We encountered during our survey of dietary supplements, a sexual enhancement product commercially available in Tokyo, in which a peak presumed to be of descarbonsildenafil was detected by LC-UV and electrospray ionization-tandem MS (ESI-MS/MS). The compound was isolated and identified as descarbonsildenafil with liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QTOF-MS), NMR, and X-ray crystal structural analysis. In addition, descarbonsildenafil showed PDE5 inhibitory activity in PDE5 inhibition assay, and its IC50 value for PDE5A1 was found to be 30 nmol/L. The results of INADEQUATE NMR and X-ray crystal structural analysis in this study provide information for the identification of descarbonsildenafil. Since this study indicates that this compound is a PDE5 inhibitor having adequate activity, it is regulated as a drug component in Japan.