Raman Analysis of Viagra and Cialis-like

16000

14000 and its analogs are potent phosphodiesterase PD-5 inhibitors and are active in the treatment of erectile 12000 dysfunction. The recent appearance of these drugs in 10000 nutraceuticals and fruit drinks makes their rapid identification an important safety issue. This study ity 8000 reveals that the LSI Dimension-P1TM (SR) Raman tens

n TM I 6000 System equipped with the LSI Vector Raman Probe 4000 can rapidly identify and distinguish individual members of the Sildenafil family of Viagra and Viagra-like 2000 compounds. Raman can therefore be used in conjunction 0 with molecular separation techniques to detect these 500 1000 1500 2000 pharmaceuticals. Raman Shift (cm-1)

40000 Hydroxy-homosildenafil 60000 35000 Homosildenafil 30000 50000

25000 40000 y t 20000 nsi 30000 tensity n

Inte 15000 I 20000 10000

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0 0 500 1000 1500 2000 500 1000 1500 2000 -1 Raman Shift (cm ) Raman Shift (cm-1)

50000 The substitution of an ethyl group for the methyl Hongdenafil moiety on the piperazine ring in homosildenafil, the addition of an hydroxy to this ethyl group 40000 hydroxy-homosildenafil or the substitution of an acetyl bridge to the phenyl ring instead of sulfate, 30000

all yield detectable changes in the Raman tensity n spectra. Three regions of these spectra show I 20000 differences in either peak distribution or in relative peak intensities. Expansion of these spectra will 10000 show details of these differences. 0 500 1000 1500 2000

-1 Copyright © 2005 Lambda Solutions, Inc. Raman Shift (cm ) Expansions of different regions of the Raman spectra illustrate the extraordinary signal to noise characteristic of the Dimension-P1 permitting clear identification of the unique molecular features within the Sildenafil family.

60000 Sildenafil 40000 Hydroxy-homosildenafil Hongdenafil 50000 Homosildenafil 30000 Sildenafil Hydroxy-homosildenafil 40000 y Hongdenafil Homosildenafil

20000 ity 30000 Intensit Intens 10000 20000

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-1 0 Raman Shift (cm ) 1400 1500 1600 Raman Shift (cm-1)

The Taladafil Family

The Taladafil (Cialis) is a related the family of Viagra-like drugs. They are also PD-5 inhibitors but they differ from the Sildenafil family in several ring structures, as illustrated here. Comparison of the Raman spectra of Taladafil and its amino analog, Aminotaladafil, illustrates that Dimension-P1TM can easily identify the similarities and differences (green circles) between these two analogs. Both taladafils are clearly distinguished by Raman spectra from the Sildenafil-like , , for example in the region marked by the green rectangle.

Tadalafil ity s ten In

500 1000 1500 2000 Raman Sh ift (cm-1) ity s ten Vardenafil In Aminotaladafil ity s

ten In

500 1000 1500 2000 Raman Shift (cm-1)

Lambda Solutions, Inc. Tel/Fax: 781-478-0170/0175 500 1000 1500 2000 411 Waverley Oaks Road www.lambdasolutions.com Raman Sh ift (cm-1) Waltham, MA 02452, U.S.A. [email protected]