Zopiclone, sold under the brand name Imovane among others, is a nonbenzodiazepine used to treat difficulty sleeping. Zopiclone is molecularly distinct from benzodiazepine drugs and is classed as a cyclopyrrolone. However, zopiclone increases the normal transmission of the neurotransmitter gamma-aminobutyric acid (GABA) in the central nervous system, via modulating benzodiazepine receptors in the same way that benzodiazepine drugs do.
Zopiclone is a sedative. It works by causing a depression or tranquilization of the central nervous system. After prolonged use, the body can become accustomed to the effects of zopiclone. When the dose is then reduced or the drug is abruptly stopped, withdrawal symptoms may result. These can include a range of symptoms similar to those of benzodiazepine withdrawal. Although withdrawal symptoms from therapeutic doses of zopiclone and its isomers (i.e., eszopiclone) do not typically present with convulsions and are therefore not considered life-threatening, patients may experience such significant agitation or anxiety that they seek emergency medical attention.
In the United States, zopiclone is not commercially available, although its active stereoisomer, eszopiclone is. Zopiclone is a controlled substance in the United States, Japan, Brazil, and some European countries, and may be illegal to possess without a prescription. However, it is readily available in other countries and is not a controlled substance.
Zopiclone is known colloquially as a “Z-drug”. Other Z-drugs include zaleplon and zolpidem and were initially thought to be less addictive than benzodiazepines. However, this appraisal has shifted somewhat in the last few years as cases of addiction and habituation have been presented. Zopiclone is recommended to be taken on a short-term basis, usually no more than a week or two. Daily or continuous use of the drug is not usually advised, and caution must be taken when the compound is used in conjunction with antidepressants, sedatives or other drugs affecting the central nervous system.