Eszopiclone is a nonbenzodiazepine hypnotic, pyrrolopyrazine derivative of the cyclopyrrolone class and is indicated for the short-term treatment of insomnia. While Eszopiclone is a hypnotic agent with a chemical structure unrelated to benzodiazepines, barbiturates, or other drugs with known hypnotic properties, it interacts with the gamma-aminobutyric acid-benzodiazepine (GABABZ) receptor complex. Subunit modulation of the GABABZ receptor chloride channel macromolecular complex is hypothesized to be responsible for some of the pharmacological properties of benzodiazepines, which include sedative, anxiolytic, muscle relaxant, and anticonvulsive effects in animal models. Eszopiclone binds selectively to the brain alpha subunit of the GABA A omega-1 receptor. The mechanism of action of Eszopiclone is not completely understood. It is thought that Eszopiclone acts on the benzodiazepine receptors as an agonist and interacts with GABA-receptor complexes. Used for the treatment of insomnia.

(R)-Zopiclone is the (R)-enantiomer of benzodiazepine modulator Zopiclone. (S)-Zopiclone binding at benzodiazepine recognition sites is about 50-fold higher than of the (R)-zopiclone, and the pharmacokinetics of the enantiomers varies between individuals differently. In rats, there is no stereo conversion from (S)- to (R)-Zopiclone, whereas (R)-Zopiclone converts to (S)-Zopiclone, which is preferentially distributed into the brain. (R)-Zopiclone is known to have sedative and anxiolytic effects and as well as effects towards locomotor activity reduction.