Screening results for non-declared synthetic phosphodiesterase-5 inhibitors being added to dietary supplements of plant origin

Abstract

Non-declared addition of synthetic phosphodiesterase-5 inhibitors (PDE-5 inhibitors) to dietary supplements (DS) of plant origin in order to stimulate potency is a serios problem. Such counterfeiting strengthens therapeutic effects produced by a product; similar effects can't occur only due to components of DS of plant origin. Synthetic PDE-5 inhibitors are both substances of official medications and their structural analogues. When synthetic PDE-5 inhibitors are consumed as components in DS in order to increase potency, it can be hazardous for consumers' health due to unpredictable or even lethal side effects. Our research goal was to reveal concentrations of non-declared synthetic PDE-5 inhibitors in DS consumed by males. Our research objects were 175 DS selected by Rospotrebnadzor in different Russian regions. Synthetic PDE-5 inhibitors were detected in samples by HPLC with diode array spectrophotometric detection and MS-detection as per guidelines developed by us and approved on by Rospotrebnadzor (MG 4.1.3331-16). Our research revealed that 36% of DS that were consumed to increase potency contained non-declared synthetic PDE-5 inhibitors with Tadalafil and Sildenafil being the most widely spread ones 42.9% and 28.6% of all counterfeit cases). Their combination or analogues of PDE-5 inhibitors were detected significantly less frequently; complicated mixtures containing three or more components were also rather rare. Contents of Tadalafil, Sildenafil, or Vardenafil in DS varied from trace quantities to concentrations that corresponded to recommended daily doses for these medications or even higher than such doses. We identified derivatives of Sildenafil and Tadalafil among PDE-5 inhibitors; their quantities varied from 1.2 mg/capsule to 24.3 mg/capsule. The developed procedure allowed detecting counterfeited DS with not only Tadalafil, Sildenafil, or Vardenafil being added to them, but also analogues of synthetic PDE-5 inhibitors.