sildenafil citrate and its Impurities
A citrate salt of Sildenafil sold under the brand name of Viagra. Sildenafil is used for the treatment of erectile dysfunction and pulmonary arterial hypertension. Sildenafil inhibits an enzyme cGMP-specific phosphodiesterase type 5 that promotes degradation of cGMP, which regulates blood flow in the penis.Reference standards of Sildenafil Citrate API,and its pharmacopeial, non pharmacopeial impurities, and stable isotopes are listed below.


4-Ethoxy-N,N-bis(2-hydroxyethyl)-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonamide
4-Ethoxy-N,N-bis(2-hydroxyethyl)-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonamide
Catalogue No.:PA 19 09590
CAS :
226956-43-0
Molecular Formula : C21H29N5O6S
Molecular Weight : 479.55


5-(5-Carboxy-2-ethoxyphenyl)-1-methyl-3-n-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one
5-(5-Carboxy-2-ethoxyphenyl)-1-methyl-3-n-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one
Catalogue No.:PA 19 09640
CAS :
147676-78-6
Molecular Formula : C18H20N4O4
Molecular Weight : 356.38


(Z)-N'-(5-Chloro-4-methyl-2-propyl-1H-imidazol-1-yl)-2-ethoxy-5-((4-ethylpiperazin-1-yl)sulfonyl)benzimidamide
(Z)-N'-(5-Chloro-4-methyl-2-propyl-1H-imidazol-1-yl)-2-ethoxy-5-((4-ethylpiperazin-1-yl)sulfonyl)benzimidamide
Catalogue No.:PA 19 09700
CAS :
NA
Molecular Formula : C22H33ClN6O3S
Molecular Weight : 497.05

![4-[2-Ethoxy-5-(1-piperazinylsulfonyl)benzoamido]-1 PA 19 09760](https://www.pharmaffiliates.com/pimages/PA1909760.jpg)
4-[2-Ethoxy-5-(1-piperazinylsulfonyl)benzoamido]-1-methyl-3-propyl-1H-pyrazole-5-carboxamide
4-[2-Ethoxy-5-(1-piperazinylsulfonyl)benzoamido]-1-methyl-3-propyl-1H-pyrazole-5-carboxamide
Catalogue No.:PA 19 09760
CAS :
300547-20-0
Molecular Formula : C21H30N6O5S
Molecular Weight : 478.57


Sildenafil Related Compound A (5-[2-Ethoxy-5-[(4-methylpiperazin-1-yl)sulfonyl]phenyl]-1-methyl-3-( (1612685)
Sildenafil Related Compound A (5-[2-Ethoxy-5-[(4-methylpiperazin-1-yl)sulfonyl]phenyl]-1-methyl-3-( (1612685)
Catalogue No.:PA USP1612685
CAS :
NA
Molecular Formula : NA
Molecular Weight : NA


3-[[[5-Aminocarbonyl-1-methyl-3-propyl-1H-pyrazol-4-yl]amino]carbonyl]-4-ethoxy-benzenesulfonyl Dimer
3-[[[5-Aminocarbonyl-1-methyl-3-propyl-1H-pyrazol-4-yl]amino]carbonyl]-4-ethoxy-benzenesulfonyl Dimer
Catalogue No.:PA 19 09960
CAS :
1391054-84-4
Molecular Formula : C34H42N8O8S
Molecular Weight : 722.81


3-[[[5-(Aminocarbonyl)-1-methyl-3-propyl-1H-pyrazol-4-yl]amino]carbonyl]-4-propoxy-benzenesulfonyl Chloride
3-[[[5-(Aminocarbonyl)-1-methyl-3-propyl-1H-pyrazol-4-yl]amino]carbonyl]-4-propoxy-benzenesulfonyl Chloride
Catalogue No.:PA 19 09970
CAS :
374776-34-8
Molecular Formula : C18H23ClN4O5S
Molecular Weight : 442.92


Ethyl 4-ethoxy-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonate
Ethyl 4-ethoxy-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonate
Catalogue No.:PA 19 09880
CAS :
1971915-89-5
Molecular Formula : C19H24N4O5S
Molecular Weight : 420.48


5-(2-methoxy-5-((4-methylpiperazin-1-yl)sulfonyl)phenyl)-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one
5-(2-methoxy-5-((4-methylpiperazin-1-yl)sulfonyl)phenyl)-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one
Catalogue No.:PA 19 09930
CAS :
263897-18-3
Molecular Formula : C21H28N6O4S
Molecular Weight : 460.55


4-(2-Methoxy-5-((4-methylpiperazin-1-yl)sulfonyl)benzamido)-1-methyl-3-propyl-1H-pyrazole-5-carboxamide
4-(2-Methoxy-5-((4-methylpiperazin-1-yl)sulfonyl)benzamido)-1-methyl-3-propyl-1H-pyrazole-5-carboxamide
Catalogue No.:PA 19 09940
CAS :
263897-17-2
Molecular Formula : C21H30N6O5S
Molecular Weight : 478.57


4-(2-Methoxy-5-((4-methylpiperazin-1-yl)sulfonyl)phenyl)-1-methyl-3-propyl-1H-pyrazole-5-carboxamide
4-(2-Methoxy-5-((4-methylpiperazin-1-yl)sulfonyl)phenyl)-1-methyl-3-propyl-1H-pyrazole-5-carboxamide
Catalogue No.:PA 19 09950
CAS :
NA
Molecular Formula : C20H29N5O4S
Molecular Weight : 435.54


3-(4,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-4-ethoxy-N-[2-(methylamino)ethyl]benzenesulfonamide Hydrochloride
3-(4,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-4-ethoxy-N-[2-(methylamino)ethyl]benzenesulfonamide Hydrochloride
Catalogue No.:PA 19 0091001
CAS :
NA
Molecular Formula : C20H29ClN6O4S
Molecular Weight : 485


5-(5-Chlorosulfonyl-2-ethoxyphenyl)-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one
5-(5-Chlorosulfonyl-2-ethoxyphenyl)-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one
Catalogue No.:PA 19 0091004
CAS :
139756-31-3
Molecular Formula : C16H17ClN4O4S
Molecular Weight : 396.85