[2] Fabbri A., Aversa A. and Isidori A. "Sildenafil and erectile dysfunction", Journal of Endocrinological Investigation , 22, 486 (1999).
[3] Medina P., Segarra G., Vila J. M., Domenech C ., Martinez-Leon J. B. and Lluch S., "Effects of sildenafil on human penile blood vessels", Urology, 56, 539 (2000).
[4] Kloner R.A., Brown M., Prisant L.M. and Collins M., "Effect of sildenafil in patients with erectile dysfunction taking antihypertensive therapy", American Journal of Hypertension, 14, 3 (2001)
[5] Stuckey B.G., Jadzinsky M.N., Murphy L.J., Montorsi F., Kadioglu A., Fraige F., Manzano P. and Deerochanawong C., " Sildenafil citrate for treatment of erectile dysfunction in men with type 1 diabetes: Results of a randomized controlled trial", DiabetesCare, 26, 84 (2003).
[6] Nurnberg H.G., Seidman S.N., Gelenberg A.J., Fava M., Rosen R. and Shabsigh R., "Depression antidepressant therapies and erectile dysfunction Clinical trials of sildenafil citrate (Viagra®) in treated and untreated patients with depression", Urology, 60, 58 (2002).
[7] Morales A. Gingell C. and Collins M., "Clinical safety of oral sildenafil citrate in the treatment of erectile dysfunction", International Journal of Impotence Research, 10, 69 (1998).
[8] Jackson G., Benjamin N., Jackson N. and Allen M.J., "Effects of sildenafil citrate on human homodynamic", American Journal of Cardiology, 83,13 (1999).
[9] Marmor M.F. and Kessler R., "Sildenafil (Viagra) and ophthalmology", Survey of Ophthalmology, 44, 153 (1999).
[10] Tracqui A. and Ludes B., "HPLC-MS for the Determination of Sildenafil Citrate (Viagra | in Biological Fluids. Application to the Salivary Excretion of Sildenafil after Oral Intake", Journal of Analytical Toxicology , 27, 88 (2003).
[11] Liu Y.M., Yang H.C.and Miao J.R., "Reversed-phase HPLC determination of sildenafil citrate tablet", Yaowu-fenxi-zazhi, 20, 61 (2000).
[12] Amir A. S. and Shaza A., "Simple and Sensitive Spectrophotometric Determination of Sildenafil Citrate in Pharmaceutical Formulations", Research Journal of Pharmacy and Technology, 10(12), 1994 (2017).
[13] Taízia D. S., Cibele R. T. and Cristina D. V., "Development and validation of alternative methods by non-aqueous acid-base titration and derivative ultraviolet spectrophotometry for quantification of sildenafil in raw material and tablets", Brazilian Journal of Pharmaceutical Sciences, 53(1), 1 (2017).
[14] Issa Y.M., El-Hawary W.F., Youssef A.F.A. and Senosy A.R., "Spectrophotometric determination of sildenafil citrate in pure form and in pharmaceutical formulations using some chromotropic acid azo dyes", Spectrochimica Acta. Part A, 7, 1297 (2010).
[15] Mohammad A., Mohammad R., Asma R., Ummay N. S. and Mohammad Z. S. "Study of in Vitro Interaction of Sildenafil Citrate with Bovine Serum Albumin by Fluorescence Spectroscopy", Pharmacology& Pharmacy, 6, 94 (2015).
[16] Érica F. B. , Elen R. S., Roberta A. M., Romeu C. R. and Orlando F. , "Voltammetric method for the determination of sildenafil citrate (Viagra) in pure form and in pharmaceutical formulations", AnalyticalLetters,43, 1046 (2010).
[17] Hesham S., "Spectrochemical Methods for the Determination of Sildenafil Citrate (Viagra) in Bulk Powder and in Pharmaceutical Dosage Form", Journal of Applied Sciences, 8, 28 (2006).
[18] Segall A.I., Vitzle M.T., Perez V.L., Palacios M.L. and Pizzorno M.T., "Simultaneous assay of sildenafil and desmethylsildenafil in human plasma using liquid chromatography–tandem mass spectrometry on silica column with aqueous– organic mobile phase", Journal of Chromatography B, 768, 277 (2002).
[19] Zhu X., Xiao S., Chen B., Zhang F., Yao S., Wan Z., Yang D. and Han H. "Simultaneous determination of sildenafil. vardenafil and adalafil as forbidden components in natural dietary supplements for male sexual potency by high-performance liquid chromatography–electrospray ionization mass spectrometry", Journal of Chromatography A, 1066, 89 (2005).
[20] Frag E. Y. Z., Zayed M. A., Omar M. M., Elashery S. E. A. and Mohamed G. G., "Electroanalytical determination of sildenafil in Viagra tablets using screen-printed and conventional carbon paste electrodes", Journal of Electroanalytical Chemistry, 7, 650 (2012).
[21] Abu Shawish H. M., Abu Ghalwa N., Saadeh S. M. and El Harazeen H., "Development of novel potentiometric sensors for determination of tartrazine dye concentration in foodstuff products", Food Chemistry, 138, 126 (2013).
[22] Khalil S., "Ion-selective electrode for the determination of trazodone in tablets" , Analyst ,124, 139 (1999).
[23] El-Ansary A.L., Issa Y.M. and Tag-Eldin A.S., "Plastic membrane selective electrodes for chlor tetracyclinium ion based onchlortetracyclinium-phosphotungstate and phosphomolybdate ion-pair associates", Electroanalysis.,13, 1203 (2001).
[24] 24-Cosofret V.V. and Buck R.P., "Pharmaceutical Applications of Membrane Sensors", Pharmaceutical Applications of Membrane Sensors,1, 50 (1992).
[25] 25-Vytras K., "The use of ion-selective electrodes in the determination of drug substances", Journal of Pharmaceutical and Biomedical Analysis, 7,789 (1989).
)
