Tsuyoshi Goromaru

Identification and Quantitative Determination of Fentanyl Metabolites in Patients by Gas Chromatography-Mass Spectrometry

Although fentanyl has been used widely as a short-acting narcotic analgesic, its metabolism in humans has not been clarified. In this study, three fentanyl metabolites were identified in the urine of eight surgical patients receiving 0.3-0.5 mg of fentanyl intravenously. The metabolites 4-N-(N-propionylanilino)piperidine, 4-N-(N-hydroxypropionylanilino)piperidine and 1-(2-phenethyl)-4-N-(N-hydroxypropionylanilino)piperidine, and unchanged fentanyl were identified by GC-mass spectrometry in urine collected 6 h after administration. Fentanyl and its main metabolite, 4-N-(N-propionylanilino)piperidine, were determined quantitatively in the urine of five additional patients receiving 0.5 mg fentanyl intravenously. Urinary excretion of fentanyl and 4-N-(N-propionylanilino)-piperidine during the first 12 h after injection accounted for 0.3-4.0% and 26 to 55% of the dose, respectively.

High-affinity [3H]6-nitroquipazine binding sites in rat brain.

6-Nitroquipazine is a very potent and selective inhibitor of neuronal 5-hydroxytryptamine (5-HT; serotonin) uptake. We have characterized the specific binding of [3H]6-nitroquipazine to rat brain membranes at 22 degrees C. The present results indicate the presence of a single saturable high-affinity binding component for [3H]6-nitroquipazine. Scatchard analysis revealed an apparent equilibrium dissociation constant (Kd) of 93.0 +/- 2.23 pM, and a maximal number of binding sites (Bmax) of 831.7 +/- 18.7 fmol/mg protein (mean +/- S.D., n = 4). The kinetically derived dissociation constant was 74.5 pM. [3H]6-Nitroquipazine binding was inhibited selectively by 5-HT uptake inhibitors, and a good correlation was demonstrated between the potency of various drugs to inhibit [3H]6-nitroquipazine binding and [3H]5-HT uptake. The highest densities of [3H]6-nitroquipazine binding were obtained in the hypothalamus and midbrain, intermediate binding was observed in the striatum, hippocampus, medulla oblongata and cortex, and the lowest binding was observed in the cerebellum. Lesioning of 5-HT neurons with p-chloroamphetamine resulted in a 72% reduction in [3H]6-nitroquipazine binding compared to controls. These results indicate that the binding site specifically labelled by [3H]6-nitroquipazine is associated with the neuronal 5-HT transporter complex. [3H]6-Nitroquipazine is an excellent radioligand for the study of the 5-HT uptake system.

Effects of benzylpiperazine derivatives on the neurotoxicity of 3,4-methylenedioxymethamphetamine in rat brain

The neurotoxicity of 3,4-methylenedioxymethamphetamine (MDMA) in rat brain was attenuated significantly by coadministration of several benzylpiperazines (p-nitrobenzylpiperazine, p-chlorobenzylpiperazine and 1-piperonylpiperazine), which were weak inhibitors for [3H]6-nitroquipazine binding to the 5-hydroxytryptamine (5-HT) transporter in rat brain. These results suggest that these benzylpiperazines may inhibit the MDMA-induced neurotoxicity by a novel neuropharmacological effect other than 5-HT uptake inhibition.

Drug effects on distribution of [3H]3,4-methylenedioxymethamphetamine in mice

The present study was undertaken to examine the drug interactions between 3,4-methylenedioxymethamphetamine (MDMA) and paroxetine or several compounds including the 3,4-methylenedioxybenzyl (piperonyl) group in mice. The time course of radioactivity in the mouse brain after i.v. administration of the tracer amount (approximately 70 ng/kg) of [3H]MDMA was altered significantly by coinjection of carrier MDMA (15 mg/kg) or by pretreatment with paroxetine (10 mg/kg, i.p., 5 min). Furthermore, the radioactivity in the brain 60 min after injection of [3H]MDMA was increased significantly by pretreatment with paroxetine, but not by pretreatment with 6-nitroquipazine, fluoxetine, clomipramine, GBR 12909 or desipramine, indicating that paroxetine-induced alteration of the brain radioactivity was not due to the inhibitory effect of 5-hydroxytryptamine (5-HT) uptake of paroxetine. The radioactivity in the brain 60 min after injection of [3H]MDMA was increased significantly by pretreatment with 3,4-methylenedioxyamphetamine (MDA), MDMA, 1-piperonylpiperazine and N, alpha-dimethylpiperonylamine, but not by pretreatment with piperonylacetone, piperonyl butoxide and piperonyl isobutyrate. HPLC analyses indicated that the alteration of brain radioactivity 60 min after injection of [3H]MDMA was, in part, due to inhibition in the metabolism of [3H]MDMA to radioactive metabolite(s). The present results suggest that a specific mechanism for the 3,4-methylenedioxyphenyl group which rapidly alters the disposition and metabolism of [3H]MDMA may exist in brain and peripheral organs of mice.

High-affinity [3H]6-nitroquipazine binding to the 5-hydroxytryptamine transport system in rat lung.

[3H]6-Nitroquipazine bound to rat lung membranes at 37 degrees with a dissociation constant (Kd) of 0.310 +/- 0.13 nM and a maximal number of binding sites (Bmax) of 1752 +/- 334 fmol/mg protein (mean +/- SD, N = 4). The binding was saturable, of high affinity and sodium dependent. Drug inhibition studies indicated that [3H]6-nitroquipazine binding in the lung is similar to that already reported in the rat brain and human platelets. Scatchard analysis indicated that 5-hydroxytryptamine (5-HT) inhibited [3H]6-nitroquipazine binding to rat lung membranes in a competitive manner. The present results suggest that [3H]6-nitroquipazine binding sites in the rat lung are associated with the uptake system of 5-HT.

Antagonism of 3,4-methylenedioxymethamphetamine-induced neurotoxicity in rat brain by 1-piperonylpiperazine

The effects of 1-piperonylpiperazine and N,alpha-dimethylpiperonylamine, which are weak inhibitors for [3H]5-hydroxytryptamine (5-HT) uptake, on 3,4-methylenedioxymethamphetamine (MDMA)-induced neurotoxicity were examined. The reductions of serotonergic parameters in the rat cerebral cortex produced by multiple administration of MDMA (10 mg/kg) were attenuated significantly by coadministration of 6-nitroquipazine (10 mg/kg), paroxetine (10 mg/kg) or 1-piperonylpiperazine (20 mg/kg), but not by N,alpha-dimethylpiperonylamine (20 mg/kg). The present data suggest that 1-piperonylpiperazine might inhibit the MDMA-induced neurotoxicity by effect(s) other than 5-HT uptake inhibition.

Systematic evaluation of nitric oxide, tetrahydrobiopterin, and anandamide levels in a porcine model of endotoxemia

PurposeUsing a lipopolysaccharide (LPS)-treated porcine model, we examined: (1) whether nitric oxide (NO), anandamide, and tetrahydrobiopterin (BH4) increased or not in early endotoxic shock; and (2) the location of the major site of production of these molecules, by comparing their concentrations in arteries and the portal and hepatic veins.MethodsTen pigs received an infusion of LPS at 1.7 μg·kg−1·h−1 via the portal vein for 240 min. Consecutive changes in systemic hemodynamics, hepatosplanchnic circulation, and oxygen delivery were measured. Furthermore, the variable changes in the concentrations of nitrite and nitrate (NOx), anandamide, and BH4 were measured. To access the effects of surgery, anesthesia, and fluid management on BH4, an experiment without LPS infusion was performed in two other animals.ResultsMean arterial pressure and cardiac index started to decrease at 60 min after LPS infusion. However, systemic vascular resistance remained unchanged. Total hepatic blood flow and hepatic oxygen delivery also decreased significantly. NOx and anandamide did not change during LPS infusion. BH4 values did not change without LPS infusion. However, BH4 values increased significantly in the arterial, portal, and hepatic circulation during LPS infusion, especially in the hepatic vein (from 136.8 ± 27.5 to 281.3 ± 123.2 mol/ml; P < 0.01).ConclusionOur data suggest that the BH4 values were significantly increased in several organs, especially in the liver during endotoxic shock. Impaired cardiac output and decreased blood pressure appeared in the early phase of porcine endotoxemia. Longer-term observation of these parameters after LPS treatment should be performed as the next step in future studies.

Changes in in vivo binding of 3H-Ro 15-1788 in mouse brain by reserpine.

The effects of reserpine on the in vivo binding of 3H-Ro 15-1788, (Ro 15-1788:ethyl 8-fluoro-5,6-dihydro-5-methyl-6-oxo-4H- imidazo[1,5a][1,4]benzodiazepine-3-carboxylate) a selective benzodiazepine antagonist, in the mouse brain were investigated. The biodistributions of tracer amounts of 3H-Ro 15-1788 in mice were significantly altered by pretreatment with reserpine (2.5 or 5.0 mg/kg, 24 h before the tracer administration). The time courses of radioactivity in the brain and the blood following i.v. injection of 3H-Ro 15-1788 with carrier Ro 15-1788 were not changed by pretreatment with reserpine, which suggested that the specific binding process might be altered by reserpine. The degree of alteration in the in vivo binding of 3H-Ro 15-1788 seemed to be dependent upon the dose of reserpine and the duration after the treatment of reserpine. The maximum changes in the biodistribution of 3H-Ro 15-1788 were observed at 1 day after injection of reserpine. The body temperature and the brain monoamine contents (dopamine, norepinephrine and 5-hydroxytryptamine) in mice were measured as indicators of pharmacological effects of reserpine, and good relationships to the degree of changes in the biodistribution of 3H-Ro 15-1788 and either the body temperature or brain monoamine contents, were observed. Furthermore, the changes in the biodistribution of 3H-Ro 15-1788 in the reserpinized mice were significantly suppressed by anti-depressant imipramine treatment. These results suggest that it would be possible to detect the in vivo drug interaction with brain benzodiazepine receptors in the living human brain using 11C-Ro 15-1788 and positron emission tomography (PET).

Isotopic Fractionation of Benzoic Acid and Hippuric Acid from Their Deuterated Analogues by High Performance Liquid Chromatography.

高速液体クロマトグラフィ (HPLC) による安息香酸 (BA) および馬尿酸 (HA) とその重水素標識体 (d5) の分離測定を試みたところ, 通常のカラムを用いて分離測定が可能であることを確認した。本方法を利用して, 重水素標識安息香酸服用後の重水素標識馬尿酸の尿中排泄速度を同位体二重希釈法により容易に測定でき, グリシン抱合能の評価に応用可能であることを認めた。

Isotopic fractionation of aminopyrine from its deuterated analogues and application for evaluation of hepatic function by capillary gas chromatography

キャピラリーガスクロマトグラフィによる重水素標識アミノピリン (AM) と非標識AMとの分離測定を試みたところ, AM-d9とAMとをほぼ完全に分離できることを認めた。これを利用して同位体希釈分析を実施し, AM投与後のラットの血中濃度の時間推移からクリアランスを求めた。四塩化炭素およびフェノバルビタール前処理により, AMのクリアランスは鋭敏に変化し, 肝機能の評価に利用できることを認めた。