Spectrofluorometric determination of pyronaridine, an antimalarial

A spectrofluorometric method for determination of pyronaridine (2-methoxy-7-chloro-10-[3’,5’-bis(pyrrolidinyl-1-methyl)-hydroxy-anilino]benzo[b]-1,5-naphthyridine tetraphosphate; PND) was established in biological samples and water solution. PND in the samples was extracted with n-heptane/isoamyl alcohol (98/2, vol/vol) at pH 10-11. After back-extraction into 0.1 N NaOH, and then placed in a bath of 60 degrees for 15 min. The fluorescence of the extract with n-heptane/isoamyl alcohol from the heated NaOH solution was measured at 394 and 458 nm. The fluorescence was linear with PND concentrations over the range of 10-1000 ng/mL. The overall recovery from rabbit whole blood, plasma, urine, liver homogenate, and water solution was 100+/-4% with a detectable limit of 10 ng/ml. the fluorescent spectra and TLC analysis showed that the method was specific for determination of unchanged PND in the biological samples. The assay was precise as indicated by a SD being 10.9 ng/ml, and coefficient of variation 4.7% estimated from 35 determinations. The reproducibility was assessed by 7 successive runs for 2 blood samples, and the values obtained were 183+/-4 ng/ml with a coefficient of variation 2.0%, and 345+/-12 ng/ml, 3.4%. Rabbit blood concentration after ig 30 mg/kg was followed up to d 13 using this method.