Indiplon is a nonbenzodiazepine, hypnotic sedative that was proposed for the treatment of insomnia. It is a high-affinity allosteric potentiator of GABAA responses that demonstrates preference for α1 subunit-containing GABAA receptors. There is minimal potential for adverse effects, residual daytime sedation, tolerance, respiratory depression. The simultaneous administration of indiplon and alcohol did not result in any significant pharmacokinetic changes. There is little risk of pharmacokinetic interaction between indiplon and any co-administered drugs. Developer (Neurocrine) decided to discontinue all clinical and marketing development of Indiplon in the United States.

Gaboxadol (or THIP) is a direct GABA mimetic ligand at delta-containing receptors. Gaboxadol went into human clinical trials to test if the drug promoted sleep. It was generally well tolerated. Gaboxadol enhances delta power in NREM sleep in humans. Gaboxadol failed in Phase III for sleep studies. The side effects of Gaboxadol have been described as mild and similar in quality to those of other GABA-mimetics. Gaboxadol is in development with Ovid Therapeutics as a treatment for Angelman syndrome, fragile X syndrome and epilepsy.

MK-3697 a drug, currently being developed by Merck, for the treatment Insomnia. MK-3697 is a potent and selective Orexin receptor type 2 antagonist.

Triclofos is primarily indicated in conditions like Insomnia, and can also be given in adjunctive therapy as an alternative drug of choice in Nausea, vertigo, labyrinthine disorders. It is also used sedate people suffering from anxiety or tension before medical investigations. Triclofos is converted to Trichloroethanol in the body .This act on brain and produces sleep. Trichloroethanol decreases time taken to fall asleep and lengthen the sleep. Triclofos is most commonly used agent for sedation in neonates as well as in older infants and children in Japan.

Levomepromazine (also known as methotrimeprazine) is a phenothiazine neuroleptic drug. It is sold in many countries under the generic name (levomepromazine) or under brand names such as Nozinan, Detenler and many more. Levomepromazine is an antipsychotic drug is commonly used as an antiemetic to alleviate nausea and vomiting in palliative care settings particularly in terminal illness. Levomepromazine is a phenothiazine with pharmacological activity similar to that of both chlorpromazine and promethazine. It has the histamine-antagonist properties of the antihistamines together with central nervous system effects resembling those of chlorpromazine. Levomepromazine's antipsychotic effect is largely due to its antagonism of dopamine receptors in the brain. In addition, it can block 5HT2 receptors and some others, like histamine, serotonin.

CHLORAL BETAINE, a chemical complex of chloral hydrate and betaine, is a nonbarbiturate sedative and hypnotic. It is indicated for sleep induction, preoperative sedation, and daytime sedation. CHLORAL BETAINE is converted to chloral hydrate in the body and its action on the central nervous system is identical with that of chloral hydrate.

Methaqualone is a depressant that modulates the activity of the GABA receptors in the brain and nervous system. It promotes relaxation, sleepiness and sometimes a feeling of euphoria. It causes a drop in blood pressure and slows the pulse rate. These properties are the reason why it was initially thought to be a useful sedative and anxiolytic. Common side effects of Methaqualone include dizziness, nausea, vomiting, diarrhea, abdominal cramps, fatigue, itching, rashes, sweating, dry mouth, tingling sensation in arms and legs, seizures and its depressant effects include reduced heart rate and respiration. The drug became banned in many countries and was withdrawn from many markets in the early 1980s.

Propiomazine is a typical antipsychotic, blocking H1 receptors and is primarily indicated in conditions Insomnia. Propiomazine was also used under brand name largon for the relief of restlessness and apprehension, preoperatively or during surgery. In addition largon was used as an adjunct to analgesics for the relief of restlessness and apprehension during labor. But this drug was discontinued.

Glutethimide is a GABA agonist that was introduced by Ciba in 1954 as a safe alternative to barbiturates to treat insomnia. Before long, however, it had become clear that glutethimide was just as likely to cause addiction and caused similarly severe withdrawal symptoms. Glutethimide was discontinued in the US by manufacturers in 1993. Current production levels in the United States point to it only being used in small-scale research.

Ethinamate was used to treat insomnia (trouble in sleeping) under the brand name VALMID, but then was replaced by other more efficacy medicines. The mechanism of action was not known. However, was studies, which showed that ethinamate inhibits carbonic anhydrases I and did not inhibit II. Nevertheless, even inhibition carbonic anhydrases I is not sufficiently strong to implicate carbonic anhydrases I in the mechanism of action.