With substandard and counterfeit medicines a dangerous and growing
problem in the developing world and elsewhere, identifying new technologies to
detect such drugs is an urgent matter.
In a new study published in the
Journal of Pharmaceutical and Biomedical Analysis, scientists from the U.S.
Pharmacopeial Convention (USP) evaluated a handheld Raman device’s potential to
detect counterfeit and substandard medicines.
The device, called TruScan®, is
currently used to test Active Pharmaceutical Ingredients (API) and finished
pharmaceutical products, and it was evaluated for its ability to differentiate
among drug products with different APIs, different brands of the same API, and
drug products having the same API but of different strengths, with focus on the
specificity and precision of the testing.
While TruScan could be used
successfully in the initial screening for authentication of the identity of
certain targeted medicines, it may not be reliable enough to establish whether
the medicines are substandard or not. The print version of the study appears in
the journal’s February issue.
“Thin Layer Chromatography (TLC)
test methods, such as Minilab®, which PQM uses on a regular basis to detect
counterfeit and substandard medicines, have been in the market for several
years. They are quite reliable, but require specific training and the use of
chemicals,” said Mustapha Hajjou, Ph.D., lead author of the study, and a
program manager for USP’s Promoting the Quality of Medicines program (PQM),
which is funded by USAID.
“There is an increased interest in other,
‘non-invasive’ spectroscopic methods to detect counterfeit medicines, including
near-infrared (NIR) and Raman spectroscopy, like the device we tested, and
those would undoubtedly be simpler to use. We just have to make sure they
produce reliable results for various types of medicines including substandard
medicines, and that is what we tried to evaluate with the TruScan device,” he
explained.
USP is a scientific, nonprofit
public health organization that sets standards for the quality of medicines,
food ingredients and dietary supplements. USP standards are used in more than
140 countries.
Antimalarial medicines artesunate
and combination sulfadoxine-pyrimethamine (SP) were used in the evaluation
because of their common use and the prevalence of counterfeit and substandard
products in markets where malaria is endemic, and because of previous
unfavorable reports of testing these products with a Raman device. Ibuprofen
and acetyl salicylic acid tablets were also used, due to their wide range of
products with different strengths—allowing the scientists to study the device’s
ability to discriminate between these products. A reference spectrum or
signature, reference standard or a formulation (whole tablet) was created first
to be compared to the spectra of other samples. Samples testing yielded either
a match or fail result.
Results for the evaluation of
antimalarials showed that the device’s precision depend on the nature and strength
of the active pharmaceutical ingredient (API). All medicines tested obtained
acceptable precision results although, for some products, the results were well
below 100 percent. The low matching results were attributed to high
fluorescence masking the Raman signal, which could generate false negative
results in authenticating medicines.
In the specificity evaluation,
the Raman device successfully differentiated APIs, which would be useful in
testing counterfeit finished products containing the wrong API. However, in the
comparison with different lots of the same product and the comparison with
similar products from different manufacturers, some samples did not match
themselves, and the SP samples from four different manufacturers matched the
comparator, showing the device is not sufficient to discriminate among these
samples.
The device was also evaluated for
its ability to detect different strengths of the same API. Acetyl salicylic
acid and acetaminophen tablets all matched the comparator product, regardless
of the sample strength, showing the device’s limitation in possibly detecting
substandard medicines from these classes of drugs.
“We concluded that TruScan will
likely detect counterfeit medicines that lack API or have the wrong API, but we
cannot rely on it to detect substandard medicines. This is especially true in
the case of fixed-dose combinations, where one API may have a strong Raman
scatter, masking the signal for other APIs. Because most of the effective
medicines treating malaria, HIV/AIDS, and tuberculosis are fixed-dose
combinations, we need to be very cautious in using this device for assessment
of substandard medicines, says Patrick Lukulay, Ph.D., vice president of USP’s
Global Health Impact Programs and program director for PQM.
Funding for the study was
provided by USAID. The contents of this study are the responsibility of the PQM
program, implemented by USP, and do not reflect the views of USAID or the
United States Government. TruScan is a registered mark of Thermo Scientific.
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