Overview
Phenibut is an unregulated supplement with GABA-B receptor agonist behavior. Originally designed as an anxiolytic for astronauts in Russia, and is prescribed in that region for GAD, social anxiety, PTSD, stuttering, ADHDH, vestibular disorder, and alcohol withdrawal
Can be purchased online as a dietary supplement
Taken orally, recreational doses range from 500 mg – 9 g (average 2.43 g).
Half life approx. 6 hours, excreted in urine unchanged and not detected in standard UDS.
Chronic use of phenibut can lead to dependence (even within days) and withdrawal when use is stopped.
Similar to alcohol and benzodiazepine withdrawal, phenibut withdrawal appears to have a range of severity.
Intoxication – similar to ETOH
AMS, psychotic symptoms, Reduced LOC, lethargy, agitation (paradoxically)
Withdrawal Syndrome + Treatment
Patients who abruptly discontinue phenibut may have progressive symptoms worsening during early withdrawal — a snowball effect.
Similar to ETOH withdrawal – anxiety, sweating, insomnia
In its most severe presentation, phenibut withdrawal can cause symptoms such as delirium, hallucinations, and seizures.
There is no standard treatment for outpatient management
However, phenibut tapers with or without adjunctive GABA agonist therapy may be successful
Slow taper, e.g. 7 -12 weeks
Adjunctive baclofen can be helpful : daily dose ranges from 3-10 mg baclofen per gram of phenibut, divided TID or QID
References:
1. Coenen NCB, Dijkstra BAG, Batalla A, Schellekens AFA. Detoxification of a Patient With Comorbid Dependence on Phenibut and Benzodiazepines by Tapering With Baclofen: Case Report. Journal of Clinical Psychopharmacology. 2019;39(5):511. doi:10.1097/JCP.0000000000001104
2. Samokhvalov AV, Paton-Gay CL, Balchand K, Rehm J. Phenibut dependence. BMJ Case Rep. 2013;2013:bcr2012008381. doi:10.1136/bcr-2012-008381
3. Weleff J, Kovacevich A, Burson J, Nero N, Anand A. Clinical Presentations and Treatment of Phenibut Toxicity and Withdrawal: A Systematic Literature Review. Journal of Addiction Medicine. 2023;17(4):407. doi:10.1097/ADM.0000000000001141