E-drug: TB drug screening methods
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I am with the US Centers for Disease Control and Prevention (CDC) based in
Atlanta. Because of the importance of drug quality, and the relative lack
of resources to test large quantities of drugs using legal reference methods
such as UV or HPLC, we have been working with the FDA to field test thin
layer chromatography (TLC) as a primary screening tool to test TB drugs.
TLC is a semi-quantitative and qualitative method to screen drugs. TLC
analysis is quantitative in that it indicates whether the sample drug being
tested is within 85% to 115% of its stated content. It is qualitative in
that it determines whether the stated drug is present at all, by comparison
to a known standard, and whether contaminants are present. The TLC methods
were published in 1992 (J Liquid Chromatography 1992; 15: 1639-53), and were
endorsed by the WHO as a simple test for primary screening of drug quality
in 1994 (WHO/Pharm/95.290). We have demonstrated (in press) that TLC can
help to identify poor quality TB drugs, and detect spurious and counterfeit
products in a timely and cost-effective manner. In our field tests, both
the sensitivity and the specificity of TLC exceed 85% when compared to the
legal reference methods.
The methods are available on request to professionals who want to use them
to monitor drug quality.
Kayla Laserson
Division of TB Elimination
International Activity
Centers for Disease Control and Prevention
Atlanta, GA 30333
404-639-8120
404-639-8604 (fax)
KEL4@cdc.gov (email)
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