Development and application of immunoassays for rapid quality control of the antimalarial drug combination artesunate-mefloquine

•A highly specific monoclonal antibody against mefloquine was produced.•Two immunoassays dcELISA and dipsticks were developed for quantification of mefloquine commercial drugs.•The dipstick for simultaneously qualitative analysis of artesunate and mefloquine was developed.•The dipsticks have the potential for artesunate-mefloquine quality control as point-of-care devices. Artesunate-mefloquine is one of the commonly-used artemisinin-based combination therapies (ACTs). Given the significance of drug quality in the management of malaria cases, the objective of this study was to develop antibody-based assays as the point-of-care (POC) tests for monitoring the quality of this ACT. Using mefloquine conjugated to a carrier protein as the immunogen, we selected a specific monoclonal antibody (mAb) against mefloquine with no cross-reactivity to other antimalarial drugs. Using this mAb, we developed a direct competitive enzyme-linked immunosorbent assay (dcELISA) and a lateral flow immunoassay (LFIA) to measure the mefloquine contents. The dcELISA for mefloquine showed a 50% inhibitory concentration (IC50) and a working range of 2.79 ng/mL and 0.58–16.37 ng/mL, respectively. With the aid of a portable optical scanner, the LFIA had a working range of 0.15–2.67 µg/mL for mefloquine. When used to measure mefloquine contents in commercial drugs, the dcELISA and LFIA results were compatible with those determined using high-performance liquid chromatography. Using the same LFIA format, we developed a combination LFIA, which correctly estimated the artesunate and mefloquine contents in commercial ACTs. Therefore, both LFIAs could be used as POC devices for rapid quality control of artesunate and mefloquine in ACTs.