Any herbal product has the potential to be named as herbal Viagra and it can be advertised as treating erectile dysfunction. The name ‘ herbal Viagra ’ comes from the brand name Viagra which is manufactured by the drug company Pfizer. (Rzepa, H.S. , 1998). There are many analogues of sildenafil,tadalfil and vardenafil which are said to be adulterated in herbal viagra products. The first sildenafil analogue found in literature was homosildenafil ( M.H. Shin, M.K. Hong, W.S. Kim, Y.J. Lee, Y.C. Jeoung , 2003). Then, 2 more analogues of sildenafil disclosed are hydroxy-homosildenafil (C.L. Mei, C.L. Yi, H.L. Jer, J. , 2006) and acetildenafil ( L. Blok-Tip, B. Zomer, F. Bakker, K.D. Hartog, M. Hamzink, J. Ten Hove, M. Vredenbregt, D. De Kaste
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Sildenafil and many of its analogues can be prepared in two steps from a half-product called Sildenafil Intermediate B by using the synthetic approach as disclosed in the Pfizer patents .( A.S. Bell, D. Brown, N.K. Terrett , 1991; A.S. Bell, N.K. Terrett ,1992; P. Ellis, N.K. Terrett , 1994)As patent literature shows that for a PDE-5inhibitors, there are few structural requirements at the C16 position, providing hundreds of chances to numbers of analogue. A change in reagents early in the synthesis is needed in analogues with variations at N3 or C19. In 2002, claim of intellectual property on thio-analogues was published in patent literature. ( D.H. Kim, J.H. Kim, K.I. Choi, Y. Kim, G. Nam, J.H. Seo, 2002) The claim is essentially a copy of the Pfizer patent but with the C- O bond exchanged for C- S bond. Thio-sildenafil and its thio-analogues are not legally registered but identified as adulterants. A sildenafil analogue regularly identified as an adulterant is aildenafil .( J.C. Reepmeyer, J.T. Woodruff, D.A. d’Avignon , 2007; K.P. Deng, Z.Y. Luo, Y. Lei , 2011) Liu et al. claims the intellectual property of aildenafil . (B. Liu, 2005; Z.J. He, K. Zhang, J. Jin, N.C. Li, Y.Q. Na, W.J. Bai, X.F. Wang, J.C. Zhu, H. Jiang, R.P. Yuan, B.F. Hong, T. Song, Y. Yang, D.X. Dai, 2006 ; J. Wang, Y. Jiang, Y. Wang, X. Zhao, Y. Cui, J. Gu, 2007) In 2007, intellectual property which is …show more content…
4 h) .( H. Porst, H. Padma-Nathan, F. Giuliano, G. Anglin, L. Varanese, R. Rosen ,2003; H. Hedelin, P. Stroberg ,2005) It therefore extends the range of chance for the user to have sex.. Known analogues of tadalafil mostly have a variation at the N-atom of the amide. Variations at that position are introduced in the final step which is shown in patent
Sildenafil and many of its analogues can be prepared in two steps from a half-product called Sildenafil Intermediate B by using the synthetic approach as disclosed in the Pfizer patents .( A.S. Bell, D. Brown, N.K. Terrett , 1991; A.S. Bell, N.K. Terrett ,1992; P. Ellis, N.K. Terrett , 1994)As patent literature shows that for a PDE-5inhibitors, there are few structural requirements at the C16 position, providing hundreds of chances to numbers of analogue. A change in reagents early in the synthesis is needed in analogues with variations at N3 or C19. In 2002, claim of intellectual property on thio-analogues was published in patent literature. ( D.H. Kim, J.H. Kim, K.I. Choi, Y. Kim, G. Nam, J.H. Seo, 2002) The claim is essentially a copy of the Pfizer patent but with the C- O bond exchanged for C- S bond. Thio-sildenafil and its thio-analogues are not legally registered but identified as adulterants. A sildenafil analogue regularly identified as an adulterant is aildenafil .( J.C. Reepmeyer, J.T. Woodruff, D.A. d’Avignon , 2007; K.P. Deng, Z.Y. Luo, Y. Lei , 2011) Liu et al. claims the intellectual property of aildenafil . (B. Liu, 2005; Z.J. He, K. Zhang, J. Jin, N.C. Li, Y.Q. Na, W.J. Bai, X.F. Wang, J.C. Zhu, H. Jiang, R.P. Yuan, B.F. Hong, T. Song, Y. Yang, D.X. Dai, 2006 ; J. Wang, Y. Jiang, Y. Wang, X. Zhao, Y. Cui, J. Gu, 2007) In 2007, intellectual property which is …show more content…
4 h) .( H. Porst, H. Padma-Nathan, F. Giuliano, G. Anglin, L. Varanese, R. Rosen ,2003; H. Hedelin, P. Stroberg ,2005) It therefore extends the range of chance for the user to have sex.. Known analogues of tadalafil mostly have a variation at the N-atom of the amide. Variations at that position are introduced in the final step which is shown in patent