Death attributed to the toxic interaction of triazolam, amitriptyline and other psychotropic drugs

A 71-year-old man was found dead in a car into which exhaust fumes had been introduced. His wife who was in the same car recovered consciousness following hospitalization. She claimed that they had both attempted suicide by taking a large number of sleeping pills. Autopsy revealed no significant external injuries or medical disorders that would have led to the husband's death. The concentrations of alcohol and carbon-monoxide hemoglobin in his whole blood were 0.26 mg/ml and < 10%, respectively. Therefore, poisoning by carbon monoxide from the exhaust fumes was ruled out, and further toxicological examinations were undertaken. Triazolam, pentobarbital, amitriptyline and bromazepam were all detected in the tissues of the victim; whole blood concentrations were 45.60, 386.4, 521.2 and 166.7 ng/g, respectively. Triazolam (7.350 ng/g) and pentobarbital (288.2 ng/g) were also detected in the whole blood of the wife, collected 17 h after admission to hospital. When evaluating these results in the light of existing literature, we concluded that the victim and his wife had indeed attempted suicide by taking triazolam and pentobarbital. However, only the man had died of triazolam poisoning due to its apparently lethal combination with amitriptyline and other psychotropic drugs which had been prescribed to treat his depression.

Effects of tetrahydroprotoberberines on dopamine D2 receptors in ventral tegmental area of rat

AIM

To compare the actions of tetrahydroprotoberberines (THPB) on dopamine (DA) D2 receptors in the ventral tegmental area (VTA) of rat.

METHODS

Extracellular single unit recording technique was used in i.v. gallamine-paralyzed rats.

RESULTS

Eleven THPB analogs tested completely attenuated the apomorphine (Apo, 20 micrograms.kg-1)-induced inhibition on VTA DA cell firing activity. The OH group on C2 at THPB was linked with the reversal of Apo-induced inhibition. Their reversal potencies (ED50, microgram.kg-1) for D2 receptors were: THPB-143 (5.6) > SPD (8.5) > Iso (17.0) > THP (33) > THB (48) > THPB-18 (66) > THPB-1 (179) > THPB-19 (408) > THPB-126 (510) > THPB-104 (1019) > THPB-10 (4815).

CONCLUSION

Among these 11 THPB, the 2-hydroxyl-THPB (THPB-143) showed the strongest antagonistic action on D2 receptors.

[Blockade of (+/-) 12-chloroscoulerine on feed-back regulation of dopamine D2 autoreceptors]

AIM

To verify whether (+/-) 12-chloroscoulerine (CSL) is antagonist or agonist effect to D2 autoreceptors.

METHODS

The levodopa content accumulated in the rat striatum was measured by HPLC-ECD, and the DA neuron firing activity in the substantia nigra zona compacta (SNC) was recorded.

RESULTS

The accumulated levodopa content induced by CSL 40 mg.kg-1 was much more than that of 1,4-butyro-lactone (BL) group (P < 0.01). After i.p. injection of apomorphine (Apo) 5 mg.kg-1, the levodopa content was decreased below that of BL group (P < 0.05). The Apo inhibition on levodopa content was completely reversed by CSL (40 mg.kg-1, i.p.) and then increased the levodopa content (2.5 +/- 1.1 micrograms.g-1) over that of Apo group (0.7 +/- 0.3 microgram.g-1, P < 0.01). In the electrophysiologic recording, Apo (15 micrograms.kg-1, i.v.) induced the decrease of SNC DA cell firing rate nearly to zero. At the accumulated dose of CSL up to 80 micrograms.kg-1 (i.v.), the inhibition of Apo was attenuated and the firing activity was restored to predrug level.

CONCLUSION

CSL showed an antagonistic action, an action to D2 autoreceptors.

Inhibition of agonist-induced Ca2+ entry in endothelial cells by myosin light-chain kinase inhibitor

Identification of the signal which links the depletion of Ca2+ stores to a Ca2+ entry pathway in the plasma membrane remains to be determined. In the present study, effects of ML-9 and wortmannin, inhibitors of myosin light-chain kinase (MLCK), on agonist-stimulated Ca2+ response were investigated in porcine aortic endothelial cells loaded with the Ca(2+)-sensitive dye fura-2. Bradykinin (BK) caused a rapid increase in [Ca2+]i, followed by a sustained increase due to the influx of Ca2+ from the extracellular space. ML-9 almost completely abolished the sustained increase in [Ca2+]i in BK-stimulated cells, while it did not affect the mobilization of Ca2+ from intracellular stores. ML-9 also abolished the sustained increase in [Ca2+]i caused by thapsigargin. Wortmannin mimicked the effect of ML-9 on the thapsigargin-stimulated Ca2+ response. These findings document for the first time the involvement of MLCK inhibitor in Ca2+ signaling in endothelial cells.

(-)-Stepholidine acts as a D1 partial agonist on firing activity of substantia nigra pars reticulata neurons in 6-hydroxydopamine-lesioned rats

(-)-Stepholidine (SPD), a novel dopamine (DA) D1 and/or D2 receptor antagonist in normosensitive animals, shows agonistic effects on D1 receptors in rotational behavior of 6-hydroxydopamine (6-OHDA)-lesioned rats. To further characterize the pharmacological properties of SPD, we investigated the effects of SPD on firing activity of substantia nigra pars reticulata (SNR) neurons in different sensitive models. In control rats, the selective D1 agonist SKF38393 (4 mg/kg, i.v.) induced inconsistent changes (i.e. increase, decrease or no change) in firing of SNR neurons. These effects were completely antagonized by SPD (i.v.), regardless of the changes induced by SKF38393. SPD (4 mg/kg), per se, increased firing by 30.9 +/- 14.4%. In reserpinized rats, SKF38393 also induced SPD-reversible inconsistent changes as in control rats. Nevertheless, SPD per se produced no alteration in firing of SNR neurons. In 6-OHDA-lesioned rats, 5/6 SNR neurons were inhibited by SKF38393. The inhibition was completely abolished by Sch23390, a selective D1 antagonist (0.5-2 mg/kg), but partially reversed by SPD (1-16 mg/kg). Moreover, SPD (4 mg/kg) itself caused SNR increased or decreased neuron firing, and these effects were completely reversed by Sch23390 (0.5-2 mg/kg) in 8/12 neurons recorded. These results suggest that SPD acts as a partial agonist to D1 receptors in 6-OHDA-lesioned rats, but as an antagonist to D1 receptors in normal and reserpinized rats.

Sensitive determination of bromazepam in human tissues using capillary gas chromatography-mass spectrometry

A reliable and sensitive gas chromatographic-mass spectrometric method was devised to determine the levels of bromazepam in human tissues. Bromazepam was extracted from body tissues using a three-step solvent extraction procedure. N-Desmethyldiazepam served as the internal standard. Selected ion monitoring with m/z 317 for bromazepam and m/z 270 for internal standard was used for quantitation. Calibration curves in all body tissues were linear over the concentration range from 50-500 ng/g. The lower detection limit in body tissues was 2-5 ng/g and the absolute recovery in body tissues was 27.8-68.0%. This method was used to determine the levels of bromazepam in tissues of an autopsied individual who had been prescribed psychotropic drugs and who was found dead in a car.

(-)-stepholidine vs 12-chloroscoulerine enantiomers on firing activity of substantia nigral dopamine neurons

AIM

To compare the potencies between (-)-stepholidine ((-)-SPD) and 12-chloroscoulerine (CSL) enantiomers on firing of substantia nigra (SN) dopamine (DA) neurons.

METHODS

Extracellular single unit recordings in paralyzed rats.

RESULTS

In rats, (-)-SPD, (-)-, ( +/- )-, and (+)-CSL attenuated i.v. apomorphine (Apo, 10 micrograms.kg-1)-induced inhibition on firing of DA cell, and their ED50 values were 15.1 (11.9-19.4), 7.8 (7.0-8.7), 12.6 (2.0-17.9) micrograms.kg-1, and 2.9 (2.6-3.3) mg.kg-1, respectively. Thus, (-)-CSL was 1 time more potent than (-)-SPD and 371 times more potent than (+)-CSL on D2 receptors. In reserpinized rats, (-)-SPD, (-)-, ( +/- )-, and (+)-CSL blocked the inhibition caused by i.v. 4 mg.kg-1 SKF-38393, with ED50 values of 0.53 (0.51-0.55), 0.51 (0.43-0.60), 1.2 (0.7-2.0), and 5.9 (4.9-7.1) mg.kg-1, respectively. The potency of (-)-CSL was similar to that of (-)-SPD on D1 receptors and 11 times higher than that of (+)-CSL.

CONCLUSION

CSL enantiomers are D1/D2 mixed antagonists as (-)-SPD. (-)-CSL is the most, while (+)-CSL is the least, potent one among them.

Effect of desipramine on spontaneous activity of hippocampal CA1 neuron after transient cerebral ischemia in rats

AIM

To study the spontaneous firing of CA1 neurons in rat hippocampus after transient cerebral ischemia and the effect of desipramine (Des) on the post-ischemic electric activity of CA1 neurons.

METHODS

Single-unit extracellular recordings were performed in rats on d 3 after 10 min of cerebral ischemia by occlusion of 4 arteries. Des and saline were injected into a tail vein. The histological changes of CA1 neurons was assessed by the neuronal density of the CA1 sector.

RESULTS

The spontaneous firing rate of CA1 neurons on d 3 after ischemia was enhanced in comparison with the control value. Des (0.2 and 0.4 mg.kg-1, i.v., n = 5 & 6, respectively) reduced dose-dependently the increase of firing rate with maximal inhibition by 6 min (58% & 85%) to 9 min (69% & 94%) (vs vehicle group, P < 0.01). About 50% cells in CA1 region showed necrotic changes.

CONCLUSION

Des antagonized the hyperexcitability of CA1 neurons after cerebral ischemia.

[Studies on function of vegetative nervous system in cardiopathic patients with heart-qi deficiency syndromes and heart-yin deficiency syndromes]

To explore the changes of the function of vegetative nervous system in the patients with the syndromes of Heart-Qi Deficiency (HQD) and Heart-Yin Deficiency (HYD), 53 cases of heart diseases were divided into HQD and HYD, the duration between heart beats, differences of blood pressure in the lying and standing position, and urine-catecholamine/24 hrs was determined separately, and compared with control group. The results showed that the duration between heart beats and heart rate in the lying position in those patients of HQD didn't manifest significant difference with control group. But in 78.9% of patients, the differences of heart rate in expiration/inspiration, surpassed 15 beats per minute, and the proportion of 30/15 was less than 1.03. Compared with control group, the difference was significant (P < 0.01). Meantime, the differences of heart rate of lying/standing position was less than 15 beats per minute, and the difference of blood pressure had an increasing tend in 47.4% of the cases. Those patients of HYD didn't show any difference in the above indexes. Urine-catecholamine/24 hrs in both of the two groups surpassed that of control group (P < 0.01). In short, this study showed that syndromes of HQD and HYD both displayed disturbed function of the vegetative nervous system, and their types and severities were correlated with the difference of Syndromes.

Agonistic actions of pergolide on firing activity of dopamine neurons in substantia nigra compacta area

AIM

To study the potency of pergolide as a D2 receptor agonist on the firing activity of substantia nigra compacta (SNC) dopamine (DA) neurons compared with that of bromocriptine and to determine whether pergolide has the nature of D1 receptor agonist in vivo.

METHODS

Extracellular single unit recording techniques.

RESULTS

Both pergolide and bromocriptine decreased the spontaneously firing rate of "sensitive" and "insensitive" DA cells. In regard of ID50 values, pergolide (11.9, 95% fiducial limits, 5.7-25.1 micrograms kg-1) was more potent than bromocriptine (7.8, 95% fiducial limits, 3.3-18.5 mg kg-1). The discharge inhibition of pergolide was attenuated following the injection of selective D2 receptor antagonist spiperone 0.25 mg kg-1 or selective D1 receptor antagonist Sch-23390 1-2 mg kg-1. However, the inhibition caused by bromocriptine was not always attenuated by spiperone.

CONCLUSION

Pergolide is 650 times more potent than bromocriptine at D2 receptors, and possesses D1 receptor agonist characteristics in vivo.

Technetium-99m N,N'-bis(2-mercapto-2-methylpropyl)-2-aminobenzylamine: technetium-99m complexes of a novel bis(aminoethanethiol) ligand

A new N2S2 ligand system, N,N'-bis(2-mercapto-2-methylpropyl)-2- aminobenzylamine, U-BAT, 1, containing uneven amine groups (two amine groups with different pKa values) for complexing [TcVO]3+, was prepared. The reaction of this novel ligand with [99mTc]pertechnetate, in the presence of stannous tartrate as the reducing agent, produces the neutral and lipid-soluble [99mTc]TcVO(U-BAT), TcS2C15H23N2O, 2. However, when the same reaction was carried out at a higher pH, 9-10, and with 30 min of heating (100 degrees C), a second neutral but more lipid-soluble complex, [99mTc]TcVO(OU-BAT), TcS2C15H21N2O, 3, was isolated. The X-ray crystallography data of the 99Tc complexes show square pyramidal coordination with N2S2 as the base and the Tc = O in the apical position. Compound 3 can be derived from 2 by an oxidation of the ligand to form an imine. After iv injection into rats, the neutral and lipid-soluble technetium-99m complexes showed significant brain uptake, 1.54 and 1.07% dose/organ at 2 min for [99mTc]TcVO(U-BAT) and TcVO(OU-BAT), respectively. The novel Tc chemistry of this new ligand system may provide a useful foundation for designing Tc complexes with a built-in redox mechanism.

Cytogenotoxicity of N-acetyl-S-(1/2-phenyl-2-hydroxyethyl)-cysteine (NAPEC) in cultured human blood lymphocytes

N-Acetyl-S-(1/2-phenyl-2-hydroxyethyl)-cysteine (NAPEC) is a cysteine conjugate derived from the glutathione conjugate of styrene oxide. The dose- and time-dependent effects of NAPEC on SCEs and cell kinetics were studied in cultured human blood lymphocyte in vitro. Different concentrations of NAPEC (0-1500 microM) were added into the lymphocyte cultures. After 36 h of exposure, both the induction of SCEs and cell-cycle delay were increased with increasing concentrations of NAPEC. When the lymphocyte cultures were exposed to 1000 microM NAPEC for 22, 36 and 72 h during a total of 72-h culture period, no significant differences in the induction of SCEs or cell-cycle delay were noticed due to 3 exposure times. These results suggest that NAPEC possesses the potential to induce SCEs and to inhibit cell-cycle progression and such potential seems to be independent of duration of exposure to NAPEC.