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Thomas P. Layloff describes the advantages of using thin-layer chromatography methods for counterfeit detection. This article contains bonus online material.
The World Health Organization estimates that potentially more than 30% of pharmaceuticals in developing nations could be counterfeit. Thin-layer chromatography (TLC) is used in these areas to detect substandard medications and help protect consumers. Portable TLC kits are economical, do not require extensive training for use, and allow for rapid screening of product in the field (1). An example of such a portable laboratory is the GPHF-Minilab, which was developed by the Global Pharma Health Fund (GPHF), a charitable organization funded by Merck KGaA.
Pharmaceutical Technology talked to Thomas P. Layloff, PhD, senior quality assurance advisor for the Supply Chain Management System, part of the President’s Emergency Plan for AIDS Relief, about the use of TLC in developing countries.
PharmTech: Can you explain why TLC is the leading method used by developing countries to screen for drugs and authenticate medicines?
Layloff: The use of TLC to determine whether the right drug is present in approximately the right amount is very widespread because of ease of application, sustainability, low cost, and very minimal support infrastructure required. For example over 300 GPHF TLC-based Minilabs have been sold and put in use all over the world. The Minilab technology requires no laboratory facilities or electricity; detection is based on visual comparisons. Since the TLC plates are single use, there is no maintenance of the chromatographic media. There are numerous other technologies which can be used to assess the above attributes but in general those are much more expensive in terms of capital, training, and maintenance costs. However, the use of TLC is not a panacea because of the limited separation capacity; cogeners of the parent drug cannot be discerned by the technology but fortunately these types of counterfeit products are expensive to manufacture and they occur in the high cost markets such as the US.
PharmTech: How is does TLC stand out from other anticounterfeiting solutions and alternative analytical-detection methods?
Layloff: In general, all anticounterfeiting solutions are chromatographically based and are coupled with various detection technologies ranging from visual to diode arrays to coupled mass spectrometers. These latter systems cost tens to hundreds of thousands of dollars and require significant infrastructure support. Although TLC cannot approach the detection and discrimination levels of these technologies, these technologies usually cannot be sustained in the developing countries. The TLC stands out for speed and cost, but there is a tradeoff in the ability to detect sophisticated counterfeit products.
PharmTech: In your opinion, what is the best approach to combat the problem of counterfeit drugs in the supply chain (e.g., on-dose and/or on-package authentication technology, serialization, in-the-field analytical detection methods)?
Layloff: Counterfeiters are in business to make money, and their activities range from petty acts, such as revising expiration dates and repackaging counterfeit products in authentic packaging, to very brilliant sophisticated synthesis of products. The best way to avoid counterfeit products is to maintain tight control on the pedigree of your supply chain from the manufacturer through to the consumer. On-package authentication is a good means to maintain control of the chain and can be useful because the authentication is an on-board pedigree confirmation. Testing is less effective because it is a destructive process and cannot be applied on large-scale distributions.
To read the special report on analytical detection methods for counterfeit drugs, see “Chemical Confirmation.”
J. Sherma, Acta Chromatographica, 19, 5–20 (2007).