Liposomal benznidazole: a high-performance liquid chromatographic determination for biodistribution studies

In this work, an isocratic high-performance liquid chromatographic method for quantitation of liposomal benznidazole (BNZ) in biological tissues is presented. The method comprises protein precipitation together with an efficient extraction of bulk or liposomal BNZ with acetonitrile-dimethylsulfoxide (1:1, v/v) at a 2:1 (extraction solvent-tissue matrix, v/v or /vw) ratio; the process is completed by a final precipitation with trichloroacetic acid. The resultant supernatants are assayed chromatographically using a Kromasil C18 (25- x 0.4-cm i.d., 100 A, 5- microm particle size), with an isocratic mobil phase consisting of acetonitrile-water (40:60, v/v), a flow rate of 0.9 mL/min, and detected at 324 nm. Bulk BNZ is used as a reference standard for the analysis of samples containing liposomal BNZ. The assay is linear over a concentration range of 0.75 (the lowest quantity of analyte determined with precision and accuracy of >or= 20%) to 25 microg/mL-g in all liquid and solid matrices. Within-day precision is better than 6.4% in plasma and 8.6% in liver, the same for the two assayed concentrations. Between-day precision is 5.4% and 12.3% in plasma and 9% and 6.9% in liver for the two assayed concentrations, respectively. The absolute recoveries range between 70% and 97%. Therefore, the method is accurate and precise to be employed for detection of minor quantities of liposomal BNZ in biological tissues.