Gaboxadol is a drug that made it far along the development process before washing out in Phase III trials. It was intended to treat insomnia, but it is not sold in the US, has not been approved by the FDA, and there are no plans to push it along the regulatory process for sleeping problems.

Early clinical studies found that Gaboxadol helped increased the length of slow wave sleep – deep sleep. It was particularly exciting because the drug worked at a biochemical level by a different mechanism than most insomnia medicines. Developers hoped that it would have very low abuse potential.

Merck, Inc, licensed gaboxadol, from Danish pharmaceutical company Lundbeck for sale in the United States. Following failure in clinical trials, Merck abandoned the drug for sleeping problems. (Merck went on to develop the orexin antagonist suvorexant.)

The scientific name is


Also known as THIP hydrochloride; Molecular formula C6H8N2O2

CAS Number 64603-91-4

It is classified as a a selective extrasynaptic GABA(A) agonist (SEGA).

Research in Germany continues to find gaboxadol works for short-term insomnia with no rebound insomnia.

Never ones to waste opportunities, the pharmaceutical industry frequently tries to turn failed drugs into successes for other illnesses. Gaboxadol doesn't work for insomnia, so there is now research into using it to treat alcoholism.

Tiagabine was the first marketed GABA uptake inhibitor, approved for treatment of seizures and panic disorders.

γ-Aminobutyric AcidA (GABAA) Agonist 4,5,6,7-Tetrahydroisoxazolo[4,5-c]pyridin-3-ol Persistently Increases Sleep Maintenance and Intensity during Chronic Administration to Rats

Effect of repeated gaboxadol administration on night sleep and next-day performance in healthy elderly subjects.

Almorexant was another once-promising insomnia drug that was abandoned in development in Jan 2011. It worked by a different method from any insomnia medication on the market, being a receptor antagonist of the OX1 and OX2 hypocretin receptors.

Indiplon was another drug that got far along and was almost approved by the FDA before it was abandoned by the drug company.

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