Zaleplon - a review of a novel sedative hypnotic used in the treatment of insomnia

Zaleplon (N-[3-(3-cyanopyrazolo[1,5-a] pyrimidin-7-yl) phenyl] -N-ethyl acetamide) is a non-benzodiazepine recently introduced for clinical use. This agent is indicated for the short-term treatment of insomnia. Preclinical studies have shown that the benzodiazepines triazolam and Ro17-1812 can substitute for zaleplon in animals trained to distinguish zaleplon from saline. The benzodiazepine antagonist flumazenil can antagonise the discriminative stimulus effect of zaleplon. These findings suggest that zaleplon is recognised by animals as a benzodiazepine agent. Zaleplon is active after ip. and oral administration in a variety of motor performance tests, including locomotor activity, rotarod and the loaded grid. Zaleplon has been shown to be active in a number of different anticonvulsant models, including the pentylenetetrazole, isoniazid and electroshock models. The compound is also reported to be active against convulsions induced by bicuculline, picrotoxin and strychnine. Studies in anxiolytic models suggest that zaleplon may have weak anxiolytic activity. From preclinical studies, it appears zaleplon possesses a reduced risk of tolerance compared to triazolam, is less likely to potentiate the effects of ethanol and is unlikely to produce amnestic effects. In man, zaleplon is rapidly absorbed and undergoes extensive presystemic metabolism. The compound has a plasma half-life of approximately one hour and is metabolised primarily via the aldehyde oxidase system to form 5-oxo-zaleplon. This metabolite, along with other minor metabolites formed in vivo, do not appear to contribute to the activity of zaleplon. Metabolites of zaleplon are excreted primarily via the urine. Phase I studies suggest that single daytime doses of zaleplon up to 15 mg are well-tolerated. Short-term impairment of performance occurs when zaleplon is administered during the day at doses greater than or equal to 20 mg. However, given the short half-life of the compound, significant impairment of daytime performance is unlikely if zaleplon is administered at bedtime or shortly after retiring for the evening. Results from Phase II/III studies suggest that zaleplon (5 - 20 mg) produces a dose-dependent reduction in sleep latency in patients suffering from primary insomnia. The clinical efficacy of zaleplon persists for at least four weeks at doses of 10 mg and 20 mg. Studies in patients with a history of drug abuse suggest that the abuse potential of zaleplon (at doses above the therapeutic dose range) is similar to that seen with the benzodiazepine triazolam.     

扎来普隆的合成工艺研究

以3’－氨基苯乙酮为原料，二氯甲烷为溶剂，在K2CO3参与下一锅法进行酰化、缩合反应，制得N－[3-(3－二早基氨基－1－氧代－2－丙烯基）苯基]乙酰胺（收率92．3％），再经溴乙烷乙基化、环合反应合成扎来普隆，总收率68％。     

新型镇静催眠药扎来普隆的合成工艺改进

以苯乙酮为原料,经硝化、还原、酰化、缩合、烃化、环合反应合成了新型镇静催眠药扎来普隆,总收率为22．1％。其结构经^1H-NMR,IR,MS得到确证。在烃化反应中,采用溴乙烷代替价格昂贵的碘乙烷,收率达90％,降低了成本,适于工业生产。     

非苯二氮(艹卓)类镇静催眠药埃佐匹克隆

埃佐匹克隆（Luneata^TM）为新型非苯二氮[艹卓]类镇静催眠药，是佐匹克隆的（S）-异构体。临床研究表明其耐受性良好，无明显反跳性失眠。已被FDA批准用于治疗成人失眠。现对其作用机制、药效学、药动学及临床评价做一介绍。     

非苯二氮类镇静催眠药埃佐匹克隆

埃佐匹克隆(Lunesta TM)为新型非苯二氮类镇静催眠药,是佐匹克隆的(S)-异构体。临床研究表明其耐受性良好,无明显反跳性失眠。已被FDA批准用于治疗成人失眠。现对其作用机制、药效学、药动学及临床评价做一介绍。     

Pharmacodynamic and pharmacokinetic profile of S 17092, a new orally active prolyl endopeptidase inhibitor, in elderly healthy volunteers. A phase I study

AIMS: The aim of this study was to characterize the pharmacodynamics and the pharmacokinetics of S 17092, a new orally active prolyl endopeptidase inhibitor following single and repeated administration in elderly healthy volunteers. METHODS: This was a double-blind, randomized, placebo-controlled, single and multiple dose study in elderly healthy male and female volunteers (n = 36). Four doses were investigated in sequential order: 100, 400, 800 and 1200 mg. Each dose was administered orally once a day in single administration and then, after a 1 week washout period, during 7 days. Pharmacodynamics were assessed by measurement of plasmatic prolyl endopeptidase (PEP) activity, quantitative electroencephalogram (EEG) and psychometric tests. S 17092 concentrations in plasma were quantified by high performance liquid chromatography with tandem mass spectrometric detection. RESULTS: PEP activity in plasma was dose-dependently inhibited both after administration of a single dose and after repeated doses of S 17092. The mean maximal inhibition was obtained within 0.5-2 h after dosing, while inhibition lasted at least 12 h after dose administration. S 17092 appeared to be a centrally active substance as it induced statistically significant modifications in EEG compared with placebo. S 17092 at 100 mg exerted an acute increase in alpha band following single administration at 4 h and 8 h postdosing. When administered repeatedly over 7 days S 17092 did not appear to induce significant lasting central nervous system (CNS) effects. In psychometric tests, response times in the numeric working memory were significantly reduced compared with placebo, following the 800 mg dose. There were some beneficial residual effects of the 1200 mg dose on day 13: delayed word recall and word recognition sensitivity improved compared with the declines noted under placebo. Maximum measured concentration (Cmax) and area under the curve (AUC) parameters increased in proportion to the dose. The terminal half-life (t(1/2)) values ranged between 9 and 31 h on day 1 and between 7 and 18 h on day 14. A high interindividual variability was observed at all dose levels. S 17092 was well tolerated with no clinically significant changes in laboratory or physical parameters observed at any dose. CONCLUSIONS: S 17092 had a potent, dose-dependent inhibitory effect on plasmatic PEP, increased alpha band EEG at the 100 mg dose and improved performance in two verbal memory tests at the 1200 mg dose while there were disruption to the vigilance task. The results obtained in elderly healthy subjects indicated that S 17092 is suitable for once-daily dosing without any serious adverse events.     

扎来普隆片的人体药动学研究

目的 :研究国产扎来普隆片在中国人体内的药动学特征。方法 :20名健康志愿者单剂量口服15mg 扎来普隆片后 ,采用高效液相色谱法测定其血浆中扎来普隆浓度。结果与结论 :扎来普隆供试片药 -时曲线符合一房室模型 ,其Cmax 为 (55 90±16 20)ng/ml ,Tmax 为 (1 05±0 32)h ,Ke为 (0 74±0 18)h -1,T1/2ke 为 (1 00±0 29)h ,AUC0～8 为 (123 70±25 64) (ng·h)/ml,AUC0～∞为 (125 20±25 80) (ng·h)/ml ,与国外文献报道基本一致。     

Computer-analysed EEG and psychometric assessment of two new non-benzodiazepine tranquillizers in healthy volunteers

The effects on CEEG, psychomotor performance and attention of diazepam 10 mg, RU 43028 100 mg, RU 32698 100 mg and placebo administered orally have been investigated in 12 healthy subjects in a double-blind controlled study. The effects of the compounds were evaluated by objective tests (CEEG, measurement of body sway, critical flicker fusion, visual reaction time, tapping test, arithmetical calculation) and subjective measurements (visual analogue scales and side-effects questionnaire). Measurements were taken before treatment and after 30 min, 2 h, 3.5 h and 6.5 h. Placebo and RU 43028 did not affect any of the tests used. Diazepam induced an increase in beta rhythms and a decrease in theta and alpha rhythms on CEEG. These expected patterns were correlated with plasma concentrations. It also induced sedative side-effects characterized by an increase of body sway and reaction time and a decrease of CFF and arithmetical calculation. RU 32698 displayed on atypical profile on CEEG with a reduction of alpha and theta rhythms without changes in beta and delta rhythms. It did not have any psychometric incapacitating effect.     

扎来普隆治疗失眠的随机、双盲双模拟、平行对照多中心临床试验

目的评价扎来普隆治疗失眠的有效性和安全性。方法采用随机、双盲双模拟、阳性药平行对照、多中心、剂量可调整的研究方法。受试者分别服用扎来普隆胶囊5～10mg,qn或唑吡坦片10mg,qn,共2wk。意向性数据集(ITT)样本224例,其中唑吡坦组112例,扎来普隆组112例。符合方案数据集(PP)样本206例,其中唑吡坦组103例,扎来普隆组103例。采用睡眠障碍评定量表(SDRS)评价治疗失眠的疗效,治疗药物副作用量表(TESS)、ECG等评价药物的安全性。结果SDRS评分在治疗结束时均较治疗前显著减少(P<0.01);治疗1wk后,唑吡坦组的有效率为62.5%,扎来普隆组的有效率为58.0%;治疗2wk后,唑吡坦组的有效率为79.5%,扎来普隆组为79.5%,2组相比较,P>0.05;2药较常见的不良反应为轻度头昏、口干、头痛、嗜睡及厌食等,扎来普隆组头昏发生率显著少于唑吡坦组(P<0.05);2组中各有小部分患者出现反跳性失眠。结论扎来普隆治疗失眠的疗效与唑吡坦相似,但不良反应发生率较低。     

新型镇静催眠药扎来普隆的合成

扎来普降是一种非苯二氮(?)类的新型镇静催眠药,以间硝基苯乙酬为原料,经还原、酰化、缩合、烃化、环合反应合成了扎来普隆(Zaleplon)。并对此工艺的还原、酰化及烃化反应进行研究,通过铁粉-冰醋酸还原酰化一锅煮工艺,合成3-(N-乙酰基)氨基苯乙酮,收率达81%。烃化反应采用TEBA相转移催化剂,用溴乙烷烃化,简化操作,成本降低。     

The pharmacology and mechanisms of action of new generation, non-benzodiazepine hypnotic agents

The new generation hypnotic drugs, zolpidem, zopiclone and zaleplon, are at least as efficacious in the clinic as benzodiazepines and may offer advantages in terms of safety. These drugs act through the BZ binding sites associated with GABAA receptors, but show some differences from benzodiazepines in pharmacological effects and mechanisms of action. Of particular interest is the finding that zolpidem shows a wide separation between doses producing sedative effects and those giving rise to other behavioural actions, and induces less tolerance and dependence than benzodiazepines. Zolpidem also demonstrates selectivity for GABAA receptors containing alpha1 subunits. Recent studies using genetically modified mice have confirmed that receptors containing alpha1 subunits play a particularly important role in mediating sedative activity, thus providing an explanation for the pharmacological profile of zolpidem.     

Effects of single and multiple doses of a new reversible MAO-A inhibitor,befloxatone, on psychomotor performance and memory in healthy subjects

The effects on memory, psychomotor performance and mood of two dosage regimens of befloxatone, a new reversible and selective MAO-A inhibitor were assessed in a randomized, double-blind, cross-over, placebo-controlled study involving 12 healthy young male volunteers. Befloxatone and a placebo were orally administered as single (5 and 10 mg) and repeated doses (10 mg once daily and 5 mg twice daily) at one week wash-out intervals. Objective tests evaluated both memory (working memory, immediate and delayed free recall of a word list, dual coding and faces recognition) and vigilance continuous performance task (CPT), and digit symbol substitution (DSST). Subjective mood and sleep were assessed using visual analogue scales and the Leeds Sleep Evaluation Questionnaire. Statistical analysis was conducted using an ANOVA with pairwise comparisons using the Student Newman Keuls procedure. Both dosage regimens of befloxatone (10 mg once daily or 5 mg twice daily) were free of any detrimental effect on vigilance (CPT) and information processing (DSST) and did not significantly disrupt short- and long-term memory (working memory, free recall of words, dual coding and faces recognition). In addition, no subjective sedation or sleep disturbances were recorded. In conclusion, this study gives no evidence to suggest that befloxatone, at a daily dose which shows potent MAO-A inhibition, has any sedative or amnestic properties likely to interfere with the activities of everyday-life in young subjects and therefore may be safely administered in depressed outpatients.     

Pharmacological properties of tracazolate: a new non-benzodiazepine anxiolytic agent

Tracazolate (ICI 136,753, 4-butylamino-1-ethyl-6-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester) demonstrated dose-related anticonflict activity in rats and mice. The potency of tracazolate appears to be one-quarter to one-half that of chlordiazepoxide. No tolerance to the anticonflict activity of either tracazolate or chlordiazepoxide was evident following 12 consecutive days of treatment. Tracazolate exhibits a much greater separation between sedative and therapeutic doses than does chlordiazepoxide. Furthermore, based on rodent studies, tracazolate should be much less likely than the benzodiazepines to potentiate the actions of barbiturates and ethanol in man. Tracazolate potentiated both the anticonvulsant and anxiolytic effects of chlordiazepoxide in rodents. Unlike benzodiazepines, tracazolate enhances the binding of benzodiazepines to its receptor site. These results suggest that tracazolate is a novel agent with potential clinical utility as an anxiolytic drug.     

The psychomotor and cognitive effects of a new antihistamine,mizolastine, compared to terfenadine,triprolidine and placebo in healthy volunteers

Eighteen healthy volunteers received mizolastine 5 mg, 15 mg or 45 mg, terfenadine 60 mg, triprolidine 10 mg or placebo in a 6-way crossover, double blind study. Following each dose, subjects performed a series of tests of cognitive function and psychomotor performance at 1, 3, 5, 8 and 24 hours post-dose. The test battery included critical flicker fusion, choice reaction time, tracking, Stroop and Sternberg memory tests and assessment of subjective sedation.Sedative effects and a concomitant reduction in psychomotor and cognitive function were observed following triprolidine, terfenadine and the highest dose of mizolastine, 45 mg, e.g. triprolidine reduced CFF threshold by 1.5 Hz and increased reaction time by 50 ms, impairments comparable to those caused by blood alcohol concentrations of 50 mg%, the legal limit in many countries. Mizolastine 5 mg did not differ significantly from placebo and at 15 mg differed only at one test point at one time.It may be concluded that mizolastine (5 mg and 15 mg) is free from disruptive effects on cognitive function and psychomotor performance, in contrast to terfenadine 60 mg, triprolidine 10 mg and mizolastine 45 mg.     

Indiplon: the development of a new hypnotic

Indiplon is a short-acting hypnotic that is currently being developed as a treatment for insomnia by Neurocrine Biosciences and Pfizer, and is expected to be marketed in mid-2006. It is a high-affinity allosteric potentiator of GABA_A responses that demonstrates preference for α1 subunit-containing GABA_A receptors. Indiplon will be an addition to the general category of newer-generation hypnotics that now includes zaleplon, zolpidem, zopiclone and eszopiclone. Clinical trials were carried out with an immediate-release capsule and a modified-release tablet and demonstrate very positive efficacy and safety profiles. The major challenge will be developing a commercial success in the crowded insomnia treatment marketplace.     

The sedative-hypnotic properties of quazepam, a new hypnotic agent

7-Chloro-1-(2,2,2-trifluoroethyl)-5-(o-fluorophenyl)-1,3-dihydro-2H-1, 4-benzodiazepine-2-thione (Sch 16134, quazepam) is a new hypnotic drug with demonstrated clinical efficacy. Quazepam has been shown in our laboratories to have potent hypnotic activity and fewer side effects at effective doses than flurazepam, which was studied concurrently. Hypnotic potency was estimated in mice via antagonism of electroshock-induced convulsions (ECS), potentiation of hexobarbital-induced sleeping time, and chlorprothixene potentiation. The respective oral ED50's (95% fiducial limits) in the 3 tests were 0.9 (0.4-2.0), 0.5 (0.3-0.8) and 0.05 (0.02-0.08) mg/kg for quazepam and 1.6 (1.1-2.3), 0.6 (0.4-1.0) and 0.11 (0.07-0.42) mg/kg for flurazepam. The duration of action of quazepam as measured by antagonism of ECS in mice was similar to that of flurazepam at equi-effective doses but quazepam had a faster onset. When potential tolerance to hypnotic efficacy was studied, quazepam did not show tolerance after dosing 20 mg/kg p.o. twice daily (b.i.d.) for 5 days, whereas tolerance was seen with flurazepam at equi-effective doses b.i.d. for 5 days. In conscious, unrestrained squirrel monkeys and cats, quazepam produced sedation with less ataxia and less evidence of CNS stimulant action than flurazepam. On the basis of the aforementioned studies, quazepam should be an effective hypnotic with less potential for ataxia, paradoxical excitation, and tolerance than flurazepam.     

Effects of three doses of 3-indole pyruvic acid on subjective and objective measures of sleep and early morning performance

The effects of 3-indole pyruvic acid (IPA) on sleep and morning after performance were investigated in 10 volunteers with previous complaints of mild insomnia. Three doses of IPA (100, 200 and 300 mg) were compared to placebo to assess their effect on sleep, cognitive function and psychomotor performance. The psychometric battery consisted of tests of Critical Flicker Fusion, Choice Reaction Time, Short Term Memory and Compensatory Tracking. The Leeds Sleep Evaluation Questionnaire was also administered shortly after waking the morning following medication. Results show that IPA had no significant effects on any aspect of sleep architecture. However, sleep efficiency was significantly higher on night 1 when subjects had taken 200 or 300 mg IPA compared to those who had received either placebo or 100 mg IPA. No further effects were found on subsequent nights with any of the treatments. There were no morning after effects of IPA on cognitive function or psychomotor performance. The ‘first night’ effect of sleeping in an unfamiliar environment possibly caused transient insomnia in the subjects and while this effect was not mitigated by placebo or 100 mg IPA, 200 and 300 mg IPA seem to exert sufficient hypnotic effects to overcome the sleep disturbance. These results suggest that the two higher doses of IPA exert a mild hypnotic action, perhaps by relieving the stress experienced in situations that are liable to cause transient insomnia.     

扎来普隆与唑吡坦治疗失眠症的多中心随机双盲对照比较

目的 :评价国产Ⅱ类新药扎来普隆治疗失眠症的有效性和安全性。方法 :采用多中心随机双盲双模拟、阳性药平行对照研究。唑吡坦组 12 0例 ,扎来普隆组 118例分别口服扎来普隆片 10mg·d- 1或唑吡坦片 10mg·d- 1。 14d为一个疗程。结果 :意向性 (ITT)分析样本病人有 2 38例。疗效评价的睡眠障碍量表 (SDRS)评分在治疗结束时较基线显著减少 (F检验 ,P <0 .0 1)。唑吡坦组的有效率77.5 % ,扎来普隆组的有效率 73.7% ,差异无显著意义 (P >0 .0 5 )。不良反应分析显示 2组较常见的不良反应为思睡、口干、便秘、头晕和头痛。结论 :国产扎来普隆与唑吡坦具有类似的疗效 ,不良反应相当。为治疗睡眠障碍的安全而有效的新药。     

Effect of zaleplon, a non-benzodiazepine hypnotic, on melatonin secretion in rabbits

Melatonin, a major hormone secreted by the pineal gland, is known to play an important role in regulation of the circadian rhythm. (N-[3-(3-cyanopyrazolo[1,5-a]pyrimidin-7-yl)phenyl]-N-ethylacetamide (zaleplon) is a non-benzodiazepine hypnotic that acts via the benzodiazepine site of the GABA(A) receptor. In the present study, we investigated the effect of zaleplon on melatonin secretion in rabbits using RIA and compared the effect to triazolam and zopiclone. Zaleplon increased a dose-dependent concentration of melatonin in rabbit plasma collected at 30 min after intravenous administration at doses of 1 and 2 mg/kg. The zaleplon-induced increase in plasma melatonin level was not blocked by flumazenil, a benzodiazepine-receptor antagonist. In contrast, triazolam and zopiclone failed to affect the plasma melatonin level. We also investigated the effect of zaleplon on intracellular cAMP in rat pinealocytes. Consequently, zaleplon had no effect on the intracellular cAMP levels in rat pinealocytes. These results of the present studies suggest that zaleplon may promote melatonin secretion and the elevation of plasma levels of melatonin may suggest an influence of zaleplon on chronobiology.     

新型安眠药加波沙朵的合成

目的合成新型安眠药加波沙朵。方法以甘氨酸乙酯盐酸盐、氯化苄和γ-丁内酯为原料,合成N-苄基甘氨酸乙酯和4-溴丁酸乙酯,经环合得到N-苄基-3-氧代-4-甲酸乙酯哌啶盐酸盐,该盐经氢化、基团保护,再与羟胺反应环合得到3-羟基-6-甲酸乙酯-4,5,6,7-四氢异唑[5,4-c]吡啶,最后去保护得到目标产物。结果与结论中间体及产物结构经IR、^1H-NMR和^13C-NMR确认。