Determination of Sildenafil Traces in Urine and Herbal Medicines

WANG, CHIEN C.; MASI, ADRIANA N.; FERNÁNDEZ, LILIANA P.

Cordoba, Argentina

Congreso; Primera Reunión Internacional de Ciencias Farmacéuticas; 2010

  DETERMINATION OF SILDENAFIL TRACES IN HERBAL MEDICINES AND HUMAN FLUID   Wang CC,  Masi AN, Fernández LP #   INQUISAL-CONICET Área de Química Analítica, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis. San Luis, Argentina   Introduction Sildenafil, popularly known as Viagra, is an effective drug for treatment of erectile dysfunction (ED)1. Since sildenafil was launched, it has being one of the most widespread drugs of use and abuse2.The illicit addition of this drug in local herbal medicine for ED treatment represent other risk for the human health. Therefore, an accurate, sensitive and robust methodology for sildenafil determination is highly required. Complexes matrixes require a clean-up step before the analyte determination. A column of a polymeric resin XAD impregnated with a cationic surfactant retained effectively sildenafil. Drug was eluted with ethanol and determined by spectrofluorimetry. At optimal experimental conditions, several samples (urine, herbal medicine) containing the drug were analyzed with satisfactory results. Experimental Materials and methods A column was filled with Amberlite XAD-1180 (Rhom-Haas) previously actived, and 10 mL (0.1 M) of hexadecyltrimethylammonium bromide (HTAB, Tokyo Kasei Industries, Japan) were added. The reagent excess was removed washing with bidistilled water. Samples of human urine and aqueous extracts of L. saururus, H.  baylahuen, B. articulata, T. vulgaris and S. apiana spiked with sildenafil (Gador, Argentina) were fed. The column was then thoroughly washed with aqueous solution pH 11 and finally eluted with 5 mL of ethanol. A middle portion of 3 mL was collected and analyzed by spectrofluorimetry (λex 310, λem 430 nm).   Results HTAB micelles positively charged interact with negatively charged molecules of sildenafil3. Micelles adsorbed on XAD-1180 resin have the capability of retaining sildenafil with two important benefices: sildenafil was effectively separated of matrix sample, and the drug was adequately preconcentrated in column. Additionally, eluted portion (5 mL of ethanol) showed a great enhancement respect to drug native fluorescence (40-field). Lower detection limit was 0.02 ng mL−1, with a lower quantification limit of 0.06 ng mL−1.   Conclusions Amberlite XAD-1180 impregnated with HTAB micelles has shown the capability of separating and concentrating sildenafil in alkaline aqueous medium. This methodology has been successfully applied for determination of sildenafil in biological and pharmaceutical samples.   Acknowledgments The authors want to thanks INQUISAL-CONICET, FONCYT and UNSL (Project 22/Q828) for the financial support.   References 1 M. Boolell, M. J. Allen, S. A. Ballard, S. Geti-Attee, G. J. Muirhead, A. M. Naylor, I.H. Osterloh and C. Jingell, Int. J. Impot. Res. (1996) 8, 47-52. 2 S. Singh, B. Prasad, A. A. Savaliya, R. P. Shah, V. M. Gohil and A. Kaur, TrAC (2009) 28, 13–28. 3 C. C. Wang, R. A. Silva, A. N. Masi, L. P. Fernández,  Anal. Methods (2010) DOI: 10.1039/b9ay00208 # Fernández, Liliana P. Tel +54 2652 425385; fax: +54 2652 430224; e-mail: lfernand@unsl.edu.ar