Development of a lateral flow dipstick for simultaneous and semi-quantitative analysis of dihydroartemisinin and piperaquine in an artemisinin combination therapy.

Dihydroartemisinin (DHA) and piperaquine (PPQ) are two drugs used in an artemisinin-based combination therapy (ACT). The circulation of counterfeit antimalarial drugs demands the development of simple, point-of-care (POC) tests for monitoring drug quality. Here we aimed to design an antibody-based lateral flow dipstick assay for simultaneous quality control of DHA and PPQ. To obtain a monoclonal antibody (mAb) for PPQ, one structural unit of the symmetric PPQ molecule was used to derive a carboxylic acid for linkage to a carrier protein as immunogen. Screening of hybridoma cells identified an mAb 4D112B2 that reacted with the PPQ-based immunogen. A highly-sensitive icELISA was designed based on this mAb, which showed 50% inhibition concentration of PPQ at 1.66 ng/mL and a working range of 0.35 - 7.40 ng/mL. The mAb showed 10.2, 15.9 and 30.4% cross reactivity to hydroxychloroquine sulfate, chloroquine and amodiaquine, respectively. No cross reactivity was observed to lumefantrine, mefloquine artemisinin and its derivatives. Using our previous DHA dipstick design, a lateral flow dipstick for simultaneous analysis of PPQ and DHA was developed. The indicator ranges for PPQ and DHA were 2 - 5 μg/mL and 250 - 500 ng/mL, respectively. The dipstick was used to semi-quantitatively analyze PPQ and DHA content in commercial ACT drugs, which produced agreeable results to those determined by high-performance liquid chromatography. This combination dipstick makes it a potential POC device for quality control of the two active ingredients in a commonly used ACT.