Quantification of pentazocine in human plasma by HPLC with electrochemical detection

Abstract A rapid and sensitive high performance liquid chromatographic method with electrochemical detector was described to measure pentazocine concentrations in plasma. The separation of pentazocine and an internal standard, levallorphan, from interfering compound in plasma was achieved by reversed phase phenyl column chromatography in combination with a solid extraction cartridge as clean-up. Analytical recoveries for pentazocine and levallorphan were determined as 88.6 % and 92.8 %, respectively. The detection limit was determined as 500 pg/ml plasma. This method has been successfully applied to the pharmacokinetic study of pentazocine in healthy male volunteers dosed rectum at 50 mg and plasma levels monitored up to 24 h after dosing.