| Drugs are special commodities that are closely related to human's health and life.Reliable quality control and quality supervision system could help prevent the production and circulation of counterfeit or inferior drugs. Involuntary occurrence of drugs with low quality could be discovered by conventional examination according to the legal quality standard, e.g. Chinese Pharmacopoeia. But it's not the case for those produced deliberately, especially by the lawbreakers who have grasped the hard core of drug quality standard and a certain discriminative technology for counterfeit or inferior drugs. They know exactly which kind of forgery cannot be detected according to the existing quality standard, and then find a way to make up the counterfeit or inferior drug for which is in line with the quality standard. Such drugs cause great disaster to human's health, or at least pose serious threats to the drug market.At present the common tricks include substituting cheap drugs for expensive ones with similar chemical structures (type I), embezzling famous brand by the same kind of drug with similar or inferior quality (type II), producing herbal medicines or health-care products adulterated with undeclared curative or even toxic ingredient (type III), and so on. These tricks vary a lot in form, content and inundated area, so do the analytical techniques employed. This paper focuses on ultraviolet (UV), near infrared (NIR) and mid infrared (IR) spectroscopy, combined with suitable spectral information processing method (chemometrics), in investigating above-mentioned 3 types of counterfeit or inferior drugs. The fundamental (method suitability) and application study was carried out.Chapter 1 Identification of the type I counterfeit drugs by UV spectroscopy(Type I: substituting cheap drugs for expensive ones with similar chemical structures)The first type of adulteration was the most primitive of all. This problem can surely be resolved by applying NIR or IR methods, considering the universality, the UV method were applied, though. 23 kinds of steroid hormones listed in Chinese Pharmacopoeia (2000 II) were selected as study objects. Convolution transform- visualization fingerprint-similarity coefficient analysis and convolution spectroscopy differential spectra technology were used to analyze their UV spectra as to investigate the similarity coefficient, differential spectra ratio and structure similarity. Concentrations (high, moderate and low) of the same sample did not influence the step convolution spectrum differential spectra rate, which was in good accordance with the rules of similarity coefficient analysis and was therefore ideal for qualitative identification. Two-step and three-step convolution spectra amplified the spectra difference, which made it easier to identify the structures even if the structures of the samples were very similar, such as dexamethasone sodium phosphate and betamethasone sodium phosphate. So convolution spectrum differential spectra outdid similarity coefficient analysis in this aspect. Comparing the two analysis methods, similarity coefficient analysis reflected the similar degree of substances, while differential spectra analysis reflected the differential degree of substances. Convolution spectrum differential spectra analysis may be a more applicable tool in this study because our purpose was to identify the differences between the authentic and false drugs.Chapter 2 Identification of the type II counterfeit or inferior drugs by NIR spectroscopy(Type II: embezzling famous brand by the same kind of drug with similar or inferior quality)The second adulteration is more advanced than the other two in technology and UV method couldn't solve these problems. Because of the availability of the control drugs, NIR method is appropriate for solving these problems. We chose 11 species, 33 batches of metronidazole tablets in the current markets as fictitious analysis objects, and the metronidazole tablets produced by LUKANQ Co. LTD as fictitious brand drugs. The NIR spectra of metronidazole tablets were collected, and analyzed by convolutiontransform-visualization fingerprint-similarity coefficient system to obtain a whole identification of the spectra, including principal agent and accessories. The results showed that similarity coefficient 0.99 was the watershed between brand drugs and non-brand drugs. It was evident that similarity coefficient analysis was more direct and objective in this study compared with the cluster analysis.Simultaneously, NIR method was also applied to analyze the concentration of the principal component, pH value and moisture of 188 batches of benzylpenicillin sodium for injection (power). The calibration model was set up and prediction research was further carried out. The quantitative studies of multiple quality parameters can also help prevent this kind of adulteration phenomenon.Chapter 3 Discrimination of type III drugs by IR spectroscopy(Type HI: herbal medicines or health-care products adulterated with undeclared curative or even toxic ingredients)Although the third adulteration technique may not involve a high technology, UV or NIR method is almost helpless in the analysis of these samples because of the complexity of traditional Chinese medicine and the lack of negative control in general. So IR method was selected in this study to make sure if sildenafil citrate was added in the 19 species health care products (major ingredients are traditional Chinese medicine) for nourish yang. The 8-strong-peaks method, that is, weighted sum (SP value), was adopted to analyze the IR spectra of the samples using HPLC result as a reference. This discrimination method summed 8 relative characteristic strong peaks (619, 818,1582cm'1 etc) intensity ratio in the IR spectra between the samples and sildenafil citrate. The SP value was zero when no sildenafil citrate added to the samples, and when sildenafil citrate was added in, the dependability between the SP values and concentrations was 0.857. The prediction results of the simulate samples were also good and therefore a basic discrimination was achieved. |
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