Extraction of Muscle Relaxants in Human Body Fluids by Solid‐Phase Extraction

Abstract

Three muscle relaxants, tolperisone, eperisone, and tizanidine, were found to be extractable from human whole blood and urine samples by solid‐phase extraction (SPE) with a Sep‐Pak C₁₈ cartridge. Their determination was made using capillary gas chromatography with nitrogen phosphorus detection. Recoveries of the three drugs were 80.0%–97.2% for whole blood and 82.0%–94.5% for urine. The coefficients of within‐day variation in terms of recovery for all compounds in whole blood and urine samples were 2.2%–9.1% and 6.9%–9.6%, respectively; those of day‐to‐day variation for the compounds in both samples were not greater than 18.1%. The regression equations for the compounds showed excellent linearity with detection limits of 1.6–7.7 ng mL⁻¹ for whole blood and 6.0–8.0 ng mL⁻¹ for urine. The data obtained for actual determination of tolperisone in a subject after ingestion of the drugs are also presented.

Keywords:

• Muscle relaxant
• tolperisone
• eperisone
• tizanidine
• solid‐phase extraction
• gas chromatography