SIMULTANEOUS ESTIMATION OF SILDINAFIL CITRATE AND DAPOXETINE HYDROCHLORIDE FROM COMBINED PHARMACEUTICAL FORMULATION USING A VALIDATED RAPID RP-HPLC METHOD
About Authors:
Nirav D.Langhneja1*, Tushar Vaja1, Dr. Vijay K. Parmar2
1M.Pharm, Department of Pharmaceutical Sciences,
2Associate Professor, Department of Pharmaceutical Sciences,
Sardar Patel University,
Vallabh Vidyanagar-388120, Gujarat.
*laghnejanirav@gmail.com
INTRODUCTION
Sildenafil citrate 1-[[3-(6,7-Dihydro -1-methyl- 7-oxo-3-propyl -1H-pyrazolo [4,3-d] pyrimidin-5-yl) -4-ethoxyphenyl]sulphonyl]-4-methyl piperazine citrate and it is a popularly known as Viagra .It is a compound of the pyrazolo-pyrimidinyl-methyl piperazine class, and is used to treat male erectile dysfunction (Boolell.M et.al 1996, Morales. A, et.al 1998). It is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 inhibitor. The structural formulae is C22H30N6O4S. It is an ampholyte with pKa value 4 (pirydinium ion) and 8.8 (benzimidazole). Sildenafil citrate is twice as soluble in methanol than in water. Its solubility decreases with pH up to 9 when it starts to increase again. Sildenafil citrate could be determined by several analytical techniques, Densitometry, spectrophotometry, colorimetry, HPLC, GC-MS, MEKC and capillary electrophoresis.

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