(42) A Case of Baclofen-Managed Phenibut Dependence With Concurrent Opioid Use Disorder

Background & Introduction: Opioid use disorder (OUD) for many patients does not occur in isolation, which can present treatment challenges when OUD is a part of a larger polysubstance use disorder with concurrent mental health conditions. Polysubstance use disorder treatments can be complex and require consistent monitoring and altering of care plans in response to the patient’s salient needs.
The following case report reviews a patient with persistent anxiety, depression with a history of suicidal ideation and attempts, to which after trialing standardized antidepressants and anxiolytics unsuccessfully, utilized illegally manufactured substances to self-medicate. The patient had a history of alcohol, opioid, benzodiazepine, crack, cocaine, crystal methamphetamine and ketamine use/misuse.
Persistent anxiety led the patient to trial phenibut, a prescribed anxiolytics available in Russia and some Eastern European countries. He sourced his phenibut powder from the black market online and developed phenibut dependency while also seeking treatment for OUD. His OUD was stabilized with injectable extended-release buprenorphine (XR-BUP), then the patient requested help to address his phenibut dependency. The case report reviews how baclofen was utilized to replace phenibut, before a baclofen taper was initiated and then bridged to a pregabalin titration for anxiety management.

Case Description: A 27-year-old male self-referred to the Virtual Opioid Dependency Program (VODP) due to OUD, he disclosed intravenous fentanyl use for the past 12 years of unknown amount, had stopped fentanyl use a few days prior and was low dosing sublingual buprenorphine (SL-BUP) from a home supply and street obtained alprazolam for withdrawal management. He had previously been treated with methadone and SL-BUP treatment from a different MOUD provider. He stabilized on 16mg SL-BUP and dosed consistently for 17 months before bridging to XR-BUP, two loading injections of 300mg, followed by 100mg monthly maintenance doses. His OUD was well managed on buprenorphine treatment.
At the time of VODP OUD treatment initiation, the client was in remission from the majority of substances with the exemption of benzodiazepines. For 2 years prior to VODP admission, he had been purchasing black market phenibut powder to manage his anxiety as he reported traditional treatments were unsuccessful. He tried to cease phenibut use, experienced withdrawal and used street alprazolam for withdrawal. A benzodiazepine taper was recommended starting with 0.25mg BID clonazepam, for which he found unsuccessful and reverted to phenibut use.
After 3.5 years of sustained OUD remission, he requested assistance to address his phenibut dependency; he was dosing 1.5-2g daily. His addiction specialist, in consultation with his psychiatrist and the patient, decided to trial baclofen to replace phenibut, and slowly taper baclofen, before introducing and titrating pregabalin for anxiety management. Baclofen was chosen due to its similar molecular structure to phenibut, and its longer half-life.
Baclofen was initiated at 20mg for 4 weeks and had to be increased to 30mg due to lingering withdrawal symptoms. After 4 weeks of 30mg he stabilized and did not experience phenibut cravings or side effects from baclofen. He was tapered on baclofen at 2.5mg/month; at every taper, it would take 2-3 days to stabilize on the lower dose. When his baclofen taper reached 22.5mg, pregabalin was introduced at 25mg.
Baclofen was slowly tapered by 2.5mg/month over 12 months while pregabalin was slowly titrated from 25mg to 200mg to reach a therapeutic dose and baclofen was stopped. The client has been in remission from phenibut dependency for 10 months, since baclofen was stopped. He has tolerated pregabalin for anxiety management and experienced significant improvements in his psychosocial wellbeing. He maintains 100mg XR-BUP monthly injections and his OUD is in remission for 4.5 years.

Conclusion & Discussion: OUD and treatment with buprenorphine and methadone is well studied; polysubstance use requires more complex treatment regimens utilizing various medications and psychosocial supports. Baclofen can be used for the treatment of phenibut dependency in the detox phase to address withdrawal symptoms, however, longer-term baclofen treatment is not well studied outside of some published case reports.
A recommended baclofen dose is 10mg per 1g of phenibut for the acute phase of withdrawal. On this recommendation, the patient should have required between 15-20mg baclofen, which was reported as too low a dose and he required 30mg to stabilize. As the patient had been using phenibut for several years, he required a longer-term baclofen treatment taper schedule to ensure he could safely cease using phenibut and sustain remission. The baclofen taper took 12 months in total.
To ensure the patient’s anxiety was managed between psychosocial and psychiatrist supports, and medication, pregabalin was chosen due to unsuccessful trials of traditional anxiolytics and antidepressants. Baclofen has shown some success in the treatment of phenibut dependency; however, longer-term treatment may be required, further study is essential to prove efficacy, and patients must address their underlying mental health conditions for successful recovery.

References: Morris, M., Espinosa, J., Lucerna, A., & Lahr, R. (2023). A case of phenibut withdrawal and treatment with baclofen. World journal of emergency medicine, 14(4), 338–340. https://doi.org/10.5847/wjem.j.1920-8642.2023.059
Samokhvalov AV, Paton-Gay CL, Balchand K, Rehm J. Phenibut dependence. BMJ Case Rep. 2013;2013:bcr2012008381. Published 2013 Feb 6. doi:10.1136/bcr-2012-008381
June 11 ESU, 2019. What Is Phenibut & The Risks of Addiction? American Addiction Centers. https://americanaddictioncenters.org/phenibut