Counterfeit ACT could support the spread of drug resistant malaria strains from South-East Asia, where chloroquine first became ineffective, to sub-Saharan Africa.
Resistance to artemisinin‐based combination therapies (ACT) on the Cambodia-Thailand border is increasing the time treatment takes to clear malaria. The World Health Organization (WHO) is working to contain the resistant strain but there are concerns counterfeit ACT will hinder efforts.
Chloroquine first became ineffective on the Cambodia-Thailand border, described by the WHO as the epicenter for malaria resistance in Asia, before the problem spread to other areas. Resistance also emerged independently in other areas, such as South America, according to the WHO.
Counterfeit and substandard ACT is contributing to resistance and could support its spread, said Patrick Lukulay, director of the promoting the quality of medicines (PQM) initiative at the US Pharmacopeia (USP).
The USP is working with regulators to educate people and reduce the prevalence of counterfeit and substandard medicines. Expansion of the programme will see the USP begin work in Nigeria next year, Lukulay said at an AAPS session, with more countries to be added in the future.
Successes in Nigeria
Nigeria is an example of what can be achieved to tackle counterfeits with limited resources, Roger Bate, of the American Enterprise Institute (AEI), said at AAPS. Research published by Bate in Malaria Journal showed drug quality in Lagos, Nigeria probably improved in recent years.
Testing old monotherapies, such as amodiaquine, mefloquine and sulphadoxine-pyrimethamine; artemisinin monotherapies; and ACT bought in Lagos pharmacies a lower percentage of substandard medicines were found in 2010 than 2007.
However, the number of counterfeits detected varied depending on which tests was used. Testing with a Minilab, a portable laboratory used for rapid screening, identified fewer substandard drugs than Raman spectroscopy.
Natural variation caused by differences between the tests is the most likely explanation, writes Bate, but there is anecdotal evidence that counterfeiters are increasingly adding roughly the right amount of active pharmaceutical ingredient (API).
The Minilab assay semi-quantitatively assesses API concentration. Consequently, counterfeit medicines containing roughly the right amount of active “might possibly fool the Minilab API assay”, writes Bate.
More resistance concerns
Adding the correct amount of API is only one aspect of producing a bioequivalent drug though. Bioequivalence requires the product to be properly formulated, a skilled process, and without this the substandard product could still cause more harm than good.
“Such drugs may have positive impact on the patients' condition, but are more likely not to cure, and are more likely to promote resistance, and thus pose a much more insidious risk”, writes Bate.
However, another, “and perhaps more likely”, interpretation is that the discrepancy is a statistical outlier, caused by differences between the tests, or unreliable methods established for Raman.