Gaboxadol (THIP)
Gaboxadol is a GABA-A agonist selective for extrasynaptic delta-subunit receptors, originally developed as a hypnotic for insomnia and later studied in Angelman and Fragile X syndromes. It reached late-stage insomnia trials but was discontinued over efficacy and psychiatric side effects at higher doses. It is not approved, and appears on the grey market as a research chemical.
01 Overview
Also known as THIP, gaboxadol enhances tonic inhibition by activating extrasynaptic GABA-A receptors containing the delta subunit, a different target from benzodiazepines and Z-drugs. Its hypnotic development for insomnia was halted in the late 2000s after phase III programs showed limited efficacy and dose-related psychiatric adverse events such as disorientation and hallucinations. It was later revived clinically for neurodevelopmental disorders.
Because it is unapproved and sometimes sold to consumers, its use outside trials is unvalidated. At recreational doses users report sedation and dissociative or hallucinatory effects, which mirror the adverse events that ended its insomnia development.
02 Mechanism
Selective agonist at extrasynaptic delta-subunit-containing GABA-A receptors, enhancing tonic inhibitory current rather than the phasic inhibition targeted by benzodiazepines.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Insomnia (investigational) | 5–15 mg | Oral | Doses studied in discontinued insomnia trials; higher doses raised psychiatric adverse events. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Sedation / sleep inductionPromotes sleep and increases slow-wave sleep in trials, though efficacy was ultimately judged insufficient. | Modest | Clinical | |
| Increased slow-wave sleepEnhances deep non-REM sleep via extrasynaptic GABA-A activation. | Measured on EEG | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Psychiatric effects (disorientation, hallucinations)Confusion, disorientation and hallucinations at higher doses, a key reason insomnia development stopped. | Severe | Dose-related | Clinical | |
| Next-day sedation and unsteadinessResidual drowsiness and impaired coordination. | Mild | Common | Clinical |