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.