A Sensitive HPLC Method for Determination of Isoniazid in Rat Plasma, Brain, Liver and Kidney

A simple and rapid reverse phase high performance liquid chromatography (RP-HPLC) method was developed and validated for quantitative determination of Isoniazid (INH) in plasma, brain, liver and kidney samples and in solid lipid nanoparticles (SLNs). Isoniazid was analyzed by using a reverse phase column (Waters, Symmetry shield RP18, 4.6 mm x 150 cm, 5 microns), with mobile phase consisting of 0.1 M phosphate buffer, pH 5 (pH adjusted with ortho phosphoric acid) and methanol and the detection was made at 254 nm using Photo Diode Array detector at a temperature of 30°C (sample 4°C). The retention time for INH was around 3.5 minutes. The calibration curves were linear (r2 0.9998) over a concentration range from 250 ng to 25,000 ng/mL. Limit of detection (LOD) was 150 ng/mL and the Limit of quantitation (LOQ) was 200 ng/mL for plasma and tissue homogenates (brain, liver and kidney). Intra and inter-day variability’s (RSD) for extraction of INH from plasma and other tissue homogenates were less than 5% and accuracy was ± 5%. The results established selectivity and suitability of the method for pharmacokinetic studies of INH from INH SLNs.