Realizing that an easy and cost-effective method capable of bothidentifying and quantifying PDE-5 inhibitors and their designeranalogs in herbal matrices would facilitate the work of controllaboratories responsible for screening illicit medicinal productsand food supplements, we aimed at designing a simple HPLC–UVmethod for this purpose. SIL was used as the only external standardto overcome the repeated use of expensive references of the analogsin routine analysis. The method was fully validated based on theguidelines of the International Conference on Harmonization (ICH).