[First-degree heart block caused by voluntary zopiclone poisoning].
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Zopiclone is a new hypnotic cyclopyrrolone with a short elimination half-life (5.3 h). The pharmacokinetic profile of this drug was studied in 7 chronic renal failure (CRF) patients given 7.5 mg nocte for 7 consecutive nights. The pharmacokinetic values obtained were compared with the corresponding values found in healthy young volunteers given the same repeated dosage regimen. C max and T max were not significantly different between the two groups but the C min of unchanged zopiclone (at 24 h) post-dosing was significantly (p less than 0.001) higher in CRF patients (8.16 +/- 5.34 ng/ml) than in healthy volunteers (1.90 +/- 0.82 ng/ml). The AUC values in CRF patients were also significantly increased during the seventh day (742 +/- 212 h ng/ml) compared to healthy subjects (408 +/- 66.5 h ng/ml) and the elimination half-life of zopiclone was also longer in CRF patients (about 8 h) than in the reference group (about 5 h). Nevertheless, the accumulation ratios remained similar in the two groups (1.09 +/- 0.18 in CRF patients and 1.02 +/- 0.2 in healthy subjects). Thus no evident accumulation of zopiclone appeared in the CRF patients. As in the healthy subjects, no metabolites were detected in the plasma of the CRF patients although at steady state the urinary excretion of zopiclone and its N-oxide and N-desmethyl derivatives (2.03% +/- 1.52% and 1.99 +/- 0.65% of the dose, respectively) was significantly decreased compared to healthy subjects (3.7% +/- 2.1% and 32.6% +/- 4.5%, respectively). Zopiclone thus represents a safe alternative to benzodiazepine hypnotic therapy in patients with renal impairment.
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To investigate the effects of zopiclone on the central nervous system, we examined the effects of zopiclone on brain monoamines such as dopamine (DA), noradrenaline (NA) and serotonin (5-HT) and their metabolites such as homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), as well as locomotor activity in comparison with those of nitrazepam and flurazepam. Zopiclone in a dose of 10 mg/kg (p.o.) significantly reduced it (p less than 0.01) in 30 min and the reduced locomotor activity persisted until 180 min. The reducing effect on locomotor activity by zopiclone was similar to that of nitrazepam and more potent than flurazepam. The effects of zopiclone on brain monoamines (MA) were examined. No significant changes in DA, NA and 5-HT were observed, but HVA and 5-HIAA were reduced. A fluorescent-histochemical study conducted simultaneously revealed almost the same results as the biochemical test results. From the facts that zopiclone inhibited locomotor activity in rats, and inhibited brain DA and 5-HT turnover, the mechanism of action of zopiclone in brain MA neurons seems to be similar to that of benzodiazepine derivatives.
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The effects of zopiclone on sleep spindles were analyzed in six normal volunteers by using an improved waveform recognition method. The appearance rate of spindles during stage 2 of NREM sleep showed a significant increase on the drug night, which returned to the baseline on the withdrawal night. The mean duration of spindles was significantly prolonged on the drug night. No definite changes were observed in the average spindle frequency. The mean amplitude of spindles had a tendency to decrease on the drug night. On the withdrawal night, the mean amplitude decreased significantly compared with that of the baseline. Our results indicate that zopiclone is one of the spindle enhancing drugs, and that its property resembles that of benzodiazepines.
The effects of zopiclone (7.5 mg/per os/day), a new non-benzodiazepine drug, on anxiety levels, time of sleep induction, hours of sleep, number of nocturnal arousals, quality of sleep and of daytime arousal were evaluated by using psychometric ratings. A random double-blind cross-over study versus nitrazepam (5.0 mg/per os/day) was performed on 20 patients affected by insomnia and generalized anxiety disorder (DSM III-R). The effects were evaluated by using the Hamilton Rating Scale for Anxiety, the Toulouse-Pieron Attention Test and a time-signed quantitative scale for anxiety. The results of the trial confirmed the effectiveness of zopiclone in the treatment of insomnia with effects similar to nitrazepam on the quality and duration of sleep and number of nocturnal arousals, but with an improvement in all the other parameters.
The effects of a minor tranquilizer, zopiclone, on endocrine system in male rats were assessed to clarify the mechanisms whereby large doses of zopiclone may induce testicular damage. 1) Zopiclone had no significant effect on plasma and tissue levels of hormones of the hypophyseo-gonadal or -thyroid system in rats given 10, 100 and 250 mg/kg/day orally for 28 days. 2) Rats given zopiclone in doses of 10 and 100 mg/kg/day orally for 14 days had lowered serum levels of PGE2 and PGF2 alpha but the testicular PGF2 alpha concentration remained unchanged. Therefore, oral administration of high doses of zopiclone to rats has no evident influence on endocrine system related to male reproduction. And these findings support our previous paper that repeated dose of zopiclone cause no significant change in plasma or epididymal TS levels, nor to any change in lipid peroxidation in testicular tissues.
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The effects of zopiclone (0.1-100 mg/kg) were studied alone and in combination with the benzodiazepine receptor antagonist Ro 15-1788 and the inverse agonist ethyl-beta-carboline-3-carboxylate (beta-CCE). Under one procedure, food-maintained responding of squirrel monkeys was punished during one component of a multiple schedule. Each 30th response during both components produced food and, during the punishment component, also produced electric shock. Intermediate doses of zopiclone (0.3-30 mg/kg) did not affect or decreased unpunished responding and produced large increases in punished responding; higher zopiclone doses decreased responding under both conditions. beta-CCE (0.1-3 mg/kg) reversed both the rate-increasing and the rate-decreasing effects of zopiclone under each condition, producing a dose-dependent shift to the right of the zopiclone dose-effect curves. All doses of beta-CCE higher than 0.1 mg/kg decreased responding when given alone. Ro 15-1788 (0.1 or 1 mg/kg), which had no effect on punished or unpunished responding, reversed both the rate-increasing and the rate-decreasing effects of zopiclone. Under a second procedure, zopiclone increased responding of squirrel monkeys maintained by food under a 5-min fixed-interval schedule at doses that did not affect or decreased responding comparably maintained in an alternate component by response-produced electric shock. These effects were also reversed by both Ro 15-1788 and beta-CCE. When administered alone, beta-CCE produced effects opposite those of zopiclone and the benzodiazepines by decreasing responding maintained by food and increasing shock-maintained responding.(ABSTRACT TRUNCATED AT 250 WORDS)
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A double-blind, randomized, cross-over study was carried out in 10 normal healthy volunteers to investigate the residual effects of 7.5 mg zopiclone, 1 mg lormetazepam, 0.25 mg triazolam, 1 mg flunitrazepam and placebo. Tests of psychomotor performance and analogues of car driving ability were administered the morning following night-time medication. Changes with respect to placebo in an information-processing task one hour after taking the medications confirmed the hypnotic efficacy of zopiclone, triazolam and flunitrazepam. Flunitrazepam also produced a significant depression of the Critical Flicker Fusion Threshold (CFF) and increased subjective ratings of sedation one hour after nocturnal dosing. Flunitrazepam impaired the reaction time on the information-processing test the morning following doses of 1 mg.
The effects of zopiclone, CL 218,872 and diazepam were compared in squirrel monkeys trained to respond under a fixed-interval (FI) schedule of food presentation. Dose-response curves were determined for each drug by administering cumulative doses i.v. during timeout periods that preceded sequential components of the FI schedule. Low and intermediate doses of zopiclone (0.03-1.0 mg/kg), CL 218,872 (0.3-3.0 mg/kg) or diazepam (0.1-1.0 mg/kg) produced dose-related increases in the rate of FI responding. The highest doses of diazepam (10.0 mg/kg) and CL 218,872 (30.0 mg/kg), but not of zopiclone (30.0 mg/kg), decreased FI responding markedly. Doses of zopiclone, CL 218,872 and diazepam that were effective in increasing FI responding were similar to the doses reported previously to increase suppressed (punished) responding in squirrel monkeys. Pretreatment with the benzodiazepine antagonists Ro 15-1788 or CGS 8216 (1.0 or 3.0 mg/kg) reduced or eliminated the increases in FI responding produced normally by intermediate doses of zopiclone, CL 218,872 or diazepam, suggesting that the rate-increasing effects of the three agonists reflect similar actions at benzodiazepine recognition sites. In contrast, Ro 15-1788 and CGS 8216 were less effective or ineffective in attenuating the marked decreases in FI responding produced by the highest doses of CL 218,872 or diazepam, suggesting that the rate-decreasing effects of these agonists are mediated differently from their rate-increasing effects.