To the Editor: Your editorial¹ on chloroquine resistance among Saudis with Plasmodium falciparum infections rightly points to the role of sublethal concentrations of drugs, noncompliance of recommended therapeutic regimens, as well as the indiscriminate usage of antimalarial formulations in the emergence of drug-resistant Plasmodium strains. To prevent the spread of drug-resistant Plasmodium strains, it would be desirable to monitor the potency and bioavailability of different antimalarials offered to the general population. Samples of chloroquine being sold at pharmacies in Dar es Salaam in Tanzania were examined for potency and dissolution rate. The nine brands complied with the USP requirement for chloroquine content, but one did not pass the dissolution test.² In Sudan, bioavailability of one of the five brands sold in chloroquine was lower than the others.³ One would sincerely hope that, like in Sierra Leone, where use of expired drugs is an established practice,⁴ postexpiry antimalarials are not offerred to the general population even in remote and isolated locations in Saudi Arabia.

Undoubtedly, poor potency and bioavailability antimalarials would be of no benefit to the individual. This would encourage the emergence of chemotherapeutic resistance among different plasmodial strains. Even patients who are sincere and serious about the compliance of the prescribed treatment would contribute to an increased resistance in the community.

The menace of poor quality antimalarials could be minimized through simple, sensitive drug assay procedures that would not require trained personnel and costly equipment. Recently, a semi-quantitative paracetamol-specific spot test that enables the screening of paracetamol in the field itself⁵ has been standardized. Similar tests for assaying different antimalarial drugs in the field would be useful in remote areas, and could ensure that no poor potency drugs were offered to the general population.

There should be no hesitation in accepting the concept of a central laboratory in Saudi Arabia to tackle national and international issues concerning malaria.¹ Integration of field monitoring of antimalarials by the proposed organization would ensure that potency, dissolution and bioavailability of antimalarials were ideal. Lastly, there are anecdotes on the bitterness or sweetness of different brands of antimalarials in pharmacy stores in metropolitan areas. Regular surveillance of the quality of active ingredients alone would establish if there are any preparations with a poor potency and bioavailability, but with a sweet taste.