Appendix I: Further comments about ρ
The most similar test and reference spectra were those of Viagra 50 mg, which showed a difference of about 1%. Over the range
400–2500 nm, ρm = 0.0122 and δa = 1.21. Because of high-profile similarity above and below 800 nm, the exclusion of 400–800-nm data had essentially no effect
on ρm or δa for Viagra 50 mg. Because of the high-profile similarity above 800 nm for Viagra 100 mg and the modest difference in visual
tablet colors, ρm and δa for Viagra 100 mg were larger when 400–800-nm data were included. Figure 10 shows slight visual-color difference between
test and referenceViagra 100 mg. The TLC results showed a single spot from test and reference Viagra products that agreed
with the TLC results from the sildenafil citrate API.
Figure 10. Photograph of test (left) and reference (right) 100-mg Viagra tablets. The test and reference products were of
slightly different visual color, as reflected in the 400–800-nm range in Figure 9.
The authors acknowledge the assistance of Mary Lego, education manager at Foss NIR Systems, in acquiring the spectra on a
Foss NIRSystems RCA XDS NIR spectrometer.
James E. Polli* is a professor, and Stephen W. Hoag is an associate professor, both at the University of Maryland School of Pharmacy, 20 Penn St., Baltimore, MD 21201, email@example.com
. Polli is also a member of Pharmaceutical Technology's editorial advisory board. Sharon Flank is CEO of InfraTrac.
*To whom all correspondence should be addressed.
Submitted: Oct. 1, 2008. Accepted: Dec. 15, 2008.
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1. Federal Food, Drug, and Cosmetic Act, Chapters 1–2,
http://www.fda.gov/opacom/laws/fdcact/fdcact1.htm, accessed June 10, 2009.
2. FDA, "Counterfeit Drugs Questions and Answers" (Rockville, MD),
http://www.fda.gov/oc/initiatives/counterfeit/qa.html, accessed June 15, 2009.
3. FDA, "New FDA Initiative to Combat Counterfeit Drugs" (Rockville, MD),
http://www.fda.gov/oc/initiatives/counterfeit/backgrounder.html, accessed June 15, 2009.
4. World Health Organization and the International Federation of Pharmaceutical Manufacturers and Associations, "Counterfeit
Drugs" (WHO, IFPMA, Geneva, 1992).
5. B.H. Murray, "Online Distribution of Counterfeit Pharmaceuticals" white paper, (Cyveillance, Arlington, VA, 2001).
6. F. Dimerik, "Bogus Pills Sold on Net, GAO Finds," Bloomberg News (Bloomberg, New York, June 18, 2004).
7. FDA, "Combating Counterfeit Drugs" (Rockville, MD, 2004),
http://www.fda.gov/oc/initiatives/counterfeit/report02_04.html, accessed June 10, 2009.
8. S. Flank, "Anticounterfeiting and NIR: A Hong Kong Diary," Pharm. Mfg. online article (2008),
http://www.pharmamanufacturing.com/articles/2008/068.html, accessed June 10, 2009.
9. A.S. Tatavarti et al., "Assessment of NIR Spectroscopy for Nondestructive Analysis of Physical and Chemical Attributes
of Sulfamethazine Bolus Dosage Forms," AAPS PharmSciTech
(01), E91–E99 (2005).
10. J.E. Polli and A.M. McLean, "Novel Direct Curve Comparison Metrics for Bioequivalence," Pharm. Res.
(6), 734–741 (2001).
11. P.R. Seo, V.R. Shah, and J.E. Polli, "Novel Metrics to Compare Dissolution Profiles," Pharm. Dev. Technol.
(2), 223–231 (2002).