Objective: Investigation of sildenafil citrate as an adulterant in the traditional liquid herbal products of the local market in Bangladesh.Methods: A reversed-phase high-performance liquid chromatographic (HPLC) method with photodiode array (PDA) detector system has been developed and validated for investigating the presence of synthetic phosphodiesterase 5 (PDE-5) enzyme inhibitor as an adulterant in the traditional herbal products. Nine of the liquid preparations (syrup), Balarista (A), Jinsant (B), Jernide (C), Bolarist (D), Sree Gopal Oil (E), Menostroge (F), Enerton (G), Ginseng (H) and Ginsin Plus (I), of six companies form local market of Bangladesh were investigated.Results: All the products (A–I) were found to contain sildenafil citrate as an adulterant. HPLC peak of the adulterant was confirmed by comparing retention time, UV spectra generated by PDA detector and peak spiking with the authentic sample of sildenafil citrate. The quantity of sildenafil citrate in A, B, C, D, E, F, G, H and I syrups were found to be 17, 22, 26, 25, 10, 24, 29, 22 and 17 mg/100 ml, respectively.Conclusion: The study indicated that all tested liquid herbal products contain sildenafil citrate as an adulterant. As PDE-5 inhibitors have severe side effects, possess drug-drug interaction and highly recommended to prescribe by registered physicians, the regulatory agency of Bangladesh should take necessary action to minimize the risk of patients
