Development and validation of a clinical HPLC method for the quantification of hydroxychloroquine and its metabolites in whole blood

Background: Therapeutic drug monitoring for hydroxychloroquine (HCQ) has been suggested to assess nonadherence and optimize treatment efficacy in systemic lupus erythematosus patients. Materials & methods: After protein precipitation, HCQ and its metabolites, desethylhydroxychloroquine and desethylchloroquine were separated on a phenyl column and monitored by fluorescence detection. The method was linear from 50 to 4000 ng/ml for HCQ. The intra-day and inter-day precision of HCQ, desethylhydroxychloroquine and desethylchloroquine ranged from 4.3 to 10.3%. LLOQ was 50 ng/ml for HCQ. Conclusion: The method is very practical and was applied to routinely monitor the steady state whole blood exposure of HCQ and its metabolites in systemic lupus erythematosus patients. It well correlated with our LC-MS/MS and another HPLC method. Plaquenil (hydroxychloroquine) is an inexpensive antimalarial drug, now regarded as a safe and reasonably effective treatment for various autoimmune rheumatic diseases including systemic lupus erythematosus. We developed a simple HPLC method for monitoring the hydroxychloroquine concentration in patient whole blood. The clinical indication for the testing is to identify patient nonadherence and optimize treatment efficacy. The method is easy to operate in a clinical laboratory. The result well correlated with other methods.