Quantitative Gas Chromatographic Analysis of [1-(4-Piperidinyl)-1,3-dihydro-2H-benzimidazole-2-one], the Basic Metabolite of Bezitramide (Burgodin®), in Human Urine

A gas chromatographic procedure with nitrogen-phosphorus detection was developed for the quantitative determination of 1-(4-piperidinyl)-1,3-dihydro-2H-benzimidazole-2-one, the basic metabolite of the narcotic analgesic bezitramide (Burgodin), in urine. Gas chromatography with mass spectrometric detection was used for confirmation. An internal standard with great structural resemblance to the basic metabolite was synthesized in our laboratory. For the isolation of the compound from urine, a liquid-liquid extraction with chloroform/isopropanol was performed. The extract was derivatized with pentafluorobenzoylchloride immediately before chromatographic analysis. The calibration curve was linear over a broad concentration range (10 to 1000 ng/mL). The quantitation limit was 10 ng/mL, and at a 250-ng/mL concentration, coefficients of variation of 2.8 and 3.4% were obtained for within-day and between-day precision, respectively. The selectivity and accuracy of the method were satisfactory. Out of 150 urine samples, mainly from persons suspected of using bezitramide or from known drug abusers, 22 samples revealed basic metabolite concentrations that ranged from 17.0 to 1695.5 ng/mL. The described method allows the quantitation of the basic metabolite of bezitramide with high sensitivity, selectivity, and precision. It can also be used to determine bezitramide abuse and to establish bezitramide overdoses.