Metabolism and the urinary excretion profile of the recently scheduled designer drug N-Benzylpiperazine (BZP) in the rat.

The metabolism of N-benzylpiperazine (BZP), a recently scheduled designer drug, in the rat has been studied by analyzing its urinary metabolites. p-Hydroxy-BZP (p-OH-BZP) was unequivocally identified as the main metabolite along with a minor metabolite m-hydroxy-BZP (m-OH-BZP), using gas chromatography-mass spectrometry and high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI MS). The time-course excretion profiles of BZP, p-OH-BZP, and m-OH-BZP in the rats were investigated after a single intraperitoneal dosing of 5 mg/kg BZP, by using an optimized analytical procedure that combines solid-phase extraction and LC-ESI MS determination. The cumulative amounts excreted within the first 48 h were approximately 25% for p-OH-BZP and 2% for m-OH-BZP, whereas 6.7% dose of the parent drug BZP was excreted unchanged within 36 h post-dosing. The concentration ratio of p-OH-BZP to m-OH-BZP was 11.6 in the first 4 h, but it increased to 22.7 in 48 h with the elapsed time post-dosing. Most of p-OH-BZP was excreted in urine within approximately 36 h post-dosing, with approximately 50% appearing as the glucuronide conjugate. The present results suggest that p-OH-BZP is the most relevant metabolite to be detected for the proof of BZP intake in the forensic and clinical analysis of human urine.

Direct determination of glucuronide and sulfate of p-hydroxymethamphetamine in methamphetamine users' urine.

Two conjugates of p-hydroxymethamphetamine (p-OHMA), p-OHMA-glucuronide (p-OHMA-Glu) and p-OHMA-sulfate (p-OHMA-Sul) have been identified in methamphetamine (MA) users' urine by using liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS-MS). The synthesis of p-OHMA-Glu and p-OHMA-Sul, and an LC-MS procedure for the simultaneous determination of MA and its four metabolites, amphetamine (AP), p-OHMA, p-OHMA-Glu and p-OHMA-Sul, in urine have also been established. After deproteinizing urine samples with methanol, LC-MS employing a C(18) semi-micro column with a gradient elution program provided the successful separations and MS determinations of these analytes within 20 min. Based on the established method, p-OHMA-Sul was detected at higher concentrations than p-OHMA-Glu in all of the three urine samples tested. These data suggest that sulfation is a major pathway in the MA phase II metabolism.

Development of simultaneous gas chromatography-mass spectrometric and liquid chromatography-electrospray ionization mass spectrometric determination method for the new designer drugs, N-benzylpiperazine (BZP), 1-(3-trifluoromethylphenyl)piperazine (TFMPP) and their main metabolites in urine.

To prove the intake of recently controlled designer drugs, N-benzylpiperazine (BZP) and 1-(3-trifluoromethylphenyl)piperazine (TFMPP), a simple, sensitive and reliable method which allows us to simultaneously detect BZP, TFMPP and their major metabolite in human urine has been established by coupling gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). GC-MS accompanied by trifluoroacetyl (TFA) derivatization and LC-MS analyses were performed after the enzymatic hydrolysis and the solid phase extraction with OASIS HLB, and BZP, TFMPP and their major metabolites, 4'-hydroxy-BZP (p-OH-BZP), 3'-hydroxy-BZP (m-OH-BZP) and 4'-hydroxy-TFMPP (p-OH-TFMPP), have found to be satisfactorily separated on a semi-micro SCX column with acetonitrile-40 mM ammonium acetate buffer (pH 4) (75:25, v/v) as the eluent. The detection limits produced by GC-MS were estimated to be from 50 ng/ml to 1 microg/ml in the scan mode, and from 200 to 500 ng/ml in the selected ion monitoring (SIM) mode. Upon applying the LC-ESI-MS technique, the linear calibration curves were obtained by using the SIM mode for all analytes in the concentration range from 10 ng/ml to 10 microg/ml. The detection limits ranged from 5 to 40 ng/ml in the scan mode, and from 0.2 to 1 ng/ml in the SIM mode. These results indicate the high reliability and sensitivity of the present procedure, and this procedure will be applicable for proof of intake of BZP and TFMPP in forensic toxicology.

In vitro confirmation of selegiline N-oxidation by flavin-containing monooxygenase in rat microsome using LC-ESI MS.

In order to investigate the conversion of selegiline (SG), a drug used in the treatment of Parkinson's disease, to selegiline N-oxide (SGO) as a major metabolic pathway for SG, rat liver microsomal incubations were carried out in vitro in the presence of NADPH. SG was transformed into SGO in vitro as described in our previous human in vivo experiment. In the kinetic studies, the Vmax/Km value of the N-oxidation at pH 8 was found to be approximately four times greater than that at pH 7.4. The N-oxidation was also found to be inhibited by methimazole, an inhibitor of the flavin-containing monooxigenase (FMO) rather than by SKF 525A, an inhibitor of cytochrome P450s, and stimulated approximately two times by n-octylamine, an stimulator of FMO. Moreover, the N-oxidation activity remained almost unchanged in the presence of NADPH even after heating at 50 degrees C for a few minutes. The present data demonstrate that the N-oxidation of SG to SGO is principally mediated by FMO.