Sedative Hypnotics zopiclone

Sedative/hypnotics zopiclone Beta-blockers propranolol, warfarin, theophylline... 

A class of sedative/hypnotic type drug that exert their effects through the benzodiazepine binding site on GABAa receptors. The class consists both of molecules that contain the benzodiazepine moiety, for example diazepam, lorazepam and flunitrazepam, and the newer, non-benzodiazepine compounds such as zolpidem, zopiclone, indiplon and zaleplon. BzRAs are primarily used for the treatment of anxiety, insomnia and to elicit varying levels of sedation. The wide selection of compounds currently available affords the prescribing clinician extensive options in terms of relative efficacies and durations of action. 

Zopiclone is widely used as a sedative-hypnotic. It is metabolized to an inactive N-desmethylated derivative and an active N-oxide compound, both of which contain chiral centres. S-Zopiclone has a 50-fold higher affinity for the benzodiazepine receptor site than the R-enantiomer. This could be therapeutically important, particularly if the formation and the urinary excretion of the active metabolite benefits the S-isomer, which appears to be the case. As the half-life of the R-enantiomer is longer than that of the S-form, it would seem advantageous to use the R-isomer in order to avoid the possibility of daytime sedation and hangover effects which commonly occur with long-acting benzodiazepine receptor agonists. 

Anxiolytics, sedatives, hypnotics (benzodiazepines, barbiturates, chloral derivatives, chlormethiazole, zopiclone, zolpidem)... 

Several drugs with novel chemical structures have been introduced more recently for use in sleep disorders. Zolpidem, an imidazopyridine, zaleplon, a pyrazolopyrimidine, and eszopiclone, a cyclopyrrolone (Figure 22-4), although structurally unrelated to benzodiazepines, share a similar mechanism of action, as described below. Eszopiclone is the (S) enantiomer of zopiclone, a hypnotic drug that has been available outside the United States since 1989. Ramelteon, a melatonin receptor agonist, is a new hypnotic drug (see Ramelteon). Buspirone is a slow-onset anxiolytic agent whose actions are quite different from those of conventional sedative-hypnotics (see Buspirone). 

The newer sedative-hypnotics that are not benzodiazepines are rapidly becoming the first-line treatment for insomnia. These agents not only have pharmacodynamic advantages over benzodiazepines in terms of their mechanism of action, but perhaps more importantly, pharmacokinetic advantages as well. Three nonbenzodiazepine sedative-hypnotic agents that are now available are zaleplon (a pyrazolopyrimidine), zopiclone (a cyclopyrrolone not available in the United States), and zolpidem (an imidazopyridine) (Figs. 8—28-8—30 Table 8—4). 

The nonbenzodiazepine sedative-hypnotics zaleplon, zolpidem, and zopiclone are replacing benzodiazepine sedative-hypnotics as first-line treatments for insomnia. Some antidepressants, such as sedating tricyclic antidepressants and trazodone, are also used as sedative-hypnotic agents for the treatment of insomnia. 

Until about 1980, it was widely accepted that the benzodiazepine structure was a prerequisite for the anxiolytic profile and for the recognition of and binding to the benzodiazepine receptor. More recently, however, a chemically unrelated drug, the cyclopyrrolone zopiclone, has been shown to be a useful sedative hypnotic with a benzodiazepine-like profile. Other chemical classes of drugs that are also structurally dissimilar to the benzodiazepines (e.g. triazolopyridazines) have also been developed and shown to have anxiolytic activity in man these non-benzodiazepines also act via the benzodiazepine receptor. Thus the term "benzodiazepine receptor ligand" has been introduced to describe all drugs, irrespective of their chemical structure, that act on benzodiazepine receptors and thereby modulate inhibitory transmission in the brain. 

Zopiclone was the first of the new sedative-hypnotics to be launched in the late 1970s and has been shown to be equi-effective with the standard sedative-hypnotic benzodiazepines such as flurazepam and temazepam. There is evidence that zopiclone may cause less "hang-over effects than the conventional benzodiazepines but some studies have shown that this drug does produce performance decrement when this is tested shortly after treatment. A similar profile has been reported for zolpidem while abercarnil... 

From the published clinical studies, it would appear that the partial agonists bretazenil and abercamil are less likely to cause physiological dependence, have lower reinforcing effects and a lower incidence of subjective effects associated with abuse liability than the conventional 1,4-benzodiazepine sedative-hypnotics. It is presently unclear whether the full agonists for the GABA-A receptor, zolpidem and zopiclone, offer a real advance in the treatment of insomnia although their adverse effect profiles and abuse liability may be lower than that of the conventional benzodiazepines. 

Zopiclone, zolpidem, and zaleplon have made major inroads in capturing significant market shares of the sedative-hypnotic market segment. 

Zopiclone. Zopiclone is a full agonist that has been shown to have sedative properties in experimental animals and to be a potent hypnotic in humans. It has a short duration of action and minimal effects on sleep architecture, which means that it has few residual effects on waking. It appears to cause less tolerance and problems on withdrawal than the classic benzodiazepines and is currently marketed as a hypnotic. 

Diazepam is better indicated if insomnia is associated with daytime anxiety. Other benzodiazepines prescribed for insomnia include nitrazepam, flur-azepam, loprazolam, lormetazepam and temazepam. The non-benzodiazepine hypnotics zaleplon, zolpidem and zopiclone are not licensed for long-term use. The sedative antipsychotic promethazine hydrochloride is sometimes used to facilitate sleep, with a 25-50 mg recommended dose. Melatonin has proved effective for some clients, mostly in regulating the sleep/waking cycle. Although evidence of efficacy is limited, some clients use herbs such as valerian and chamomile. If Mr AB will finally be diagnosed with depression, a trial with an antidepressant will be indicated. 

Some work in our laboratories was also devoted to improve the preparation process of carbamoyl chlorides containing tertiary alkylamine functions,such as N-chloro-carbonyl, N -methyl piperazine hydrochloride. This carbamoyl chloride is for example used in the synthesis of the sedative and hypnotic pharmaceutical Zopiclone as shown in scheme 122 (Ref. 175). 

Fluconazole, itraconazole and ketoconazole very markedly increase the serum levels of midazolam and triazolam, thereby increasing and prolonging their sedative and amnesic effects. Similar but smaller effects are seen with itraconazole or ketoconazole and alprazolam and with itraconazole and brotizolam. Even less effect is seen with etizolam and itraconazole and no important interaction occurs between estazolam and itraconazole. Small effects are found with the non-benzodiazepine hypnotic, zolpidem, with ketoconazole and even less effects with zopiclone and itraconazole. 

Zopiclone appears to counter the stimulant effects of caffeine more easily than caffeine counters the sedative effects ofzopiclone. No pharmacokinetic interaction occurred between zolpidem and caffeine (given as one cup of coffee containing caffeine 300 mg), and the hypnotic effects of zolpidem were unchanged. ... 

Drugs employed have sedative or hypnotic properties with a rapid onset and induce memory loss during the period when the drug is active. The most-prevalent drugs detected, apart from alcohol, are the benzodiazepines and h5 notics (zolpidem and zopiclone). A wide range of other drugs, such as GHB, ketamine, sildenafil, methadone, buprenorphine, diphenhydramine, trimeprazine, acepromazine, thiopental, pentobarb, doxylamine, and cyamemazine, have also been reported in DFC cases. 

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