MONITORING OF ADHERENCE TO THE 14-DAY COURSE OF PRIMAQUINEIN PATIENTS WITH PLASMODIUM VIVAX MALARIA: APPLICATION OF LIQUID CHROMATOGRAPHY MASS SPECTROMETRY (LC/MS/MS) FOR DETERMINATION OF PRIMAQUINE IN DRIED BLOOD SPOT SAMPLES

Abstract

Primaquine (PQ) is only antimalarial drug for treatment relapse malaria in vivax malaria patient. The long treatment course of primaquine (14 days) related to limits of patient’s compliance which affect to treatment efficacy. Therefore, There are monitoring of adherence to the 14-day course of primaquine in vivax malaria patients. This study aims to the develop and validate a liquid chromatography-mass spectrometry method for determination of primaquine in dried blood spot (DBS) samples. Sample preparation was performed by two-step liquid-liquid extraction with organic solvents. The separation was carried out on a reversed-phase column (50 x 4.6 mm.I.D.) with the mobile phase consisting of 0.1% formic acid and methanol (80:20, v:v) running at a flow rate of 0.5 ml/min. The mass spectrometry was operated with positive electrospray ionization and multiple reactions monitoring (MRM) mode. The ion transitions of PQ and IS were 260.1 m/z to 243.3 m/z and 249.1 m/z to 233.1 m/z, respectively. The limits of quantification of PQ were 1 ng ml−1. Good precision and accuracy (both within-day and day-to-day assays) with good linearity (r2>0.997) and high recovery were over 80 %. Excellent correlation (r = 0.991) was observed between the analysis of PQ in paired whole blood and DBS samples. Patients’ adherence to primaquine therapy was assessed based on primaquine concentrations in finger-prick dried blood spot (DBS) samples and interview questionnaires. Results suggest that the 14-day primaquine when given as an anti-relapse, together with a 3- day blood schizontocidal chloroquine, remains an effective treatment for P. vivax infection in this area with a cure rate of virtually 100% during the 42-day follow-up. Based on the analysis of primaquine concentrations in DBS collected from patients on days 3, 7, and 14 of treatment, adherence rates of as high as 95-98% was observed.