Viagra Research Today is a free monthly online journal that collates and summarizes the latest research about Viagra, including details on sildenafil, erectile dysfunction, impotence, side-effects, alternatives.

1H, 13C, 15N NMR analysis of sildenafil base and citrate (Viagra) in solution, solid state and pharmaceutical dosage forms.

Wawer I, Pisklak M, Chilmonczyk Z

Department of Physical Chemistry, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1, 02097 Warsaw, Poland. wawer@pluton.farm.amwaw.edu.pl

Sildenafil citrate (SC) (Viagra) and sildenafil base in pure form are easily and unequivocally characterized by multinuclear NMR spectroscopy. Analysis of chemical shifts indicates that: (i) N6-H forms intramolecular hydrogen bonds, (ii) N25 is protonated in the salt and (iii) intermolecular OH...N hydrogen bonds involving N2 and N4 are present in the solid sildenafil citrate. 13C CPMAS NMR method has been proposed for the identification and quantitation of Viagra in its pharmaceutical formulations.

Published 9 August 2005 in J Pharm Biomed Anal, 38(5): 865-70.
Full-text of this article is available online (may require subscription).

© 2004-2008 Viagra Research Today. All Rights Reserved.