A sensitive and specific liquid chromatography–mass spectrometry method for determination of metacavir in rat plasma

A sensitive and specific liquid chromatography–electrospray ionization-mass spectrometry (LC–ESI-MS) method has been developed and validated for the quantification of metacavir in rat plasma using tinidazole as an internal standard (I.S.). Following ethyl acetate extraction, the analytes were separated on a Shim-pack ODS (4.6 μm, 150 mm × 2.0 mm I.D.) column and analyzed in selected ion monitoring (SIM) mode with a positive ESI interface using the respective [M + H]+ ions, 266 for metacavir and 248 for tinidazole. The method was validated over the concentration range of 1–600 ng/mL for metacavir. Between and within-batch precisions (R.S.D.%) were all within 15% and accuracy (%) ranged from 92.2 to 105.8%. The lower limit of quantification (LLOQ) was 1 ng/mL. The extraction recovery was on average 89.8%. The validated method was used for the pharmacokinetic study of metacavir in rats.