Use of HPLC with a Photodiode Array Detector to Identify Sildenafil Citrate as an Adulterant in Herbal Products of Bangladesh

The present study investigated the presence of specific PDE-5 inhibitors in the most popular marketed liquid herbal products in Bangladesh by HPLC system to confirm their safe use. Cyclic nucleotide phosphodiesterases (PDE) is a ubiquitous enzyme in the human cell that is the essential regulator of cyclic nucleotide signaling with diverse physiological functions.

A reversed-phase high-performance liquid chromatographic (HPLC) method with a 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 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. The results indicated that the herbal companies of Bangladesh use large amount of synthetic PDE–5 inhibitors such as sildenafil citrate in their formulations. Some products even contain a high amount of sildenafil citrate compared to others.

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 the 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.

According to our investigation, sildenafil citrate was found to be an adulterant in all of the evaluated liquid herbal preparations used for erectile disfunction. Along with other PDE-5 inhibitors, sildenafil citrate carries substantial risks for adverse effects and possible drug interactions. The illicit addition of this synthetic agent, sildenafil, to herbal products poses a grave threat that could result in life-threatening consequences. In order to reduce potential hazards to patients, it is vital that Bangladesh's drug regulatory agency acknowledges these findings and swiftly implement necessary measures to minimize future risks to patients.