Baclofen
Baclofen is a depressant and muscle relaxant of the butyric acid class that acts as a GABA-B receptor agonist.12 Originally synthesized in 1962 to treat epilepsy, it proved ineffective for that purpose but was later approved in 1977 for managing muscle spasticity.31 Chemically related to phenibut, pregabalin, and gabapentin, it produces sedation, anxiety suppression, and moderate euphoria. It has also been researched as a potential treatment for alcohol dependence.42
Contents
Dosage & Duration
Dosage
Significant risk of blackout and respiratory depression above 125 mg. Tolerance develops rapidly with repeated use.
Duration
Subjective Effects
The baclofen experience is dominated by muscle relaxation, sedation, and anxiety suppression, with a mild euphoria reported at recreational doses. The overall character is frequently compared to phenibut, a structurally related GABA-B agonist, though baclofen is generally considered less recreational. Sensory alteration is essentially absent; the experience is defined by its depressant body effects and a calm, dulled mental state.
Physical
Pronounced muscle relaxation and a heavy, sedated body feeling are the core physical effects, often accompanied by drowsiness, weakness, and dizziness. Nausea, headaches, and impaired motor coordination can occur, and respiratory depression becomes a serious risk at high doses.
Sedation
Uncomfortable
Cognitive
The headspace is calm and anxiolytic, with reduced anxiety as the most consistently reported mental effect alongside a mild euphoria. At higher doses, concentration and memory become noticeably impaired, and thinking takes on a foggy, sedated quality.
Emotional
Suppressions
Reagent Testing
Loading reagent data
Pharmacology
Pharmacodynamics
Baclofen acts as an agonist at the GABA-B receptor, binding to both the B1 and B2 subunits on pre- and post-synaptic neurons.5 Receptor activation causes neuronal hyperpolarization through potassium influx, reducing presynaptic calcium entry and decreasing the release of excitatory neurotransmitters, which inhibits both mono- and polysynaptic reflex transmission at the spinal cord.51 Baclofen also blocks α2δ subunit-containing voltage-gated calcium channels, though with weak affinity (Ki = 156 μM) that is considered likely not clinically relevant. GABA-B receptor activation is additionally thought to reduce dopaminergic activity in the mesolimbic pathway.5
Pharmacokinetics
Baclofen is rapidly absorbed through the gastrointestinal tract following oral administration, with a bioavailability of approximately 70-85%.6 Only about 15% of the oral dose is metabolized in the liver, primarily through deamination.57 The elimination half-life following oral administration ranges from approximately 2 to 6 hours, with longer estimates of approximately 5.6 to 6.8 hours also described.51
Dangerous
Highest riskThese combinations are considered extremely harmful and should always be avoided. Reactions to these drugs taken in combination are highly unpredictable and have a potential to cause death.
Caution
Use cautionThese combinations are not usually physically harmful, but may produce undesirable effects, such as physical discomfort or overstimulation. Extreme use may cause physical health issues. Synergistic effects may be unpredictable. Care should be taken when choosing to use this combination.
Tolerance
GABAergic depressants
Harm Potential
Addiction & Dependence
Psychological
ModerateModerate abuse potential with risk of psychological dependence. Compulsive redosing has been reported as an after effect of use.
Physical
HighPhysical dependence develops with chronic use, potentially occurring within weeks of regular dosing at low or high doses. Withdrawal syndrome resembles benzodiazepine and alcohol withdrawal, with symptoms ranging from anxiety, tremors, and insomnia to severe manifestations including hallucinations, delirium, psychosis, seizures, and extreme muscle rigidity resembling neuroleptic malignant syndrome.81 Abrupt discontinuation is not advised; gradual tapering is necessary.1
Toxicity
CNS depression including sedation, somnolence, and ataxia occurs at therapeutic and recreational doses; overdose may cause altered mental status, hypothermia, and coma that can mimic brain death.9
Respiratory depression and insufficiency may occur, particularly at higher doses or in overdose; risk increases significantly when combined with other CNS depressants.5
Cardiovascular depression is possible at high doses; overdose may cause bradycardia, tachycardia, hypertension, and cardiac conduction abnormalities, though these effects are uncommon.5
Rhabdomyolysis may occur if baclofen use is stopped abruptly after chronic administration; this is a withdrawal complication rather than a direct toxic effect during use.1
Baclofen should be avoided in chronic kidney disease and end-stage renal disease as even small doses can cause excessive toxicity due to impaired drug clearance; this represents accumulation toxicity rather than direct nephrotoxicity.11
Psychosis Risk
Psychosis, hallucinations (auditory, visual, and tactile), delusions, delirium, confusion, disorientation, and mania may occur during withdrawal from chronic use, particularly with abrupt discontinuation.81 These psychiatric symptoms are associated with the withdrawal syndrome rather than acute intoxication.12
Seizure Risk
Seizures may occur in overdose or with abrupt discontinuation after chronic use.1 Withdrawal-related seizures are a serious concern requiring gradual tapering when discontinuing therapy.5 High-dose combinations with sedatives may also precipitate de novo seizures.
History & Culture
Discovery and Development
Baclofen was first synthesized in 1962 by Swiss chemist Heinrich Keberle at Ciba-Geigy in Basel, Switzerland.13 The compound was designed with the intention of enhancing the lipophilicity of gamma-aminobutyric acid (GABA) to enable penetration of the…
Legality
International
1961 Single Convention: baclofen is not scheduled.
1971 Convention on Psychotropic Substances: baclofen is not scheduled.
1988 Convention: baclofen is not listed in precursor Tables I or II.
By Country
References
Source Pages
Citations
- (n.d.). Ozobax- baclofen solution. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=92153f69-bc9b-4bef-9a8e-751effde5c7e#ozobax-baclofen-oral-solution1234567891011
- (n.d.). Classics in Chemical Neuroscience: Baclofen. ACS Chemical Neuroscience. https://doi.org/10.1021/acschemneuro.0c0025412
- (n.d.). Baclofen therapeutics, toxicity, and withdrawal. AAPS PharmSciTech. https://pmc.ncbi.nlm.nih.gov/articles/PMC8182184/1
- (January 2023). Baclofen for alcohol use disorder. The Cochrane Database of Systematic Reviews, 1(1). https://doi.org/10.1002/14651858.cd012557.pub31
- (2021). Baclofen therapeutics, toxicity, and withdrawal: A narrative review. SAGE Open Medicine, 9. https://doi.org/10.1177/2050312121102219712345678
- (May 2022). StatPearls [Internet]. StatPearls Publishing. https://pubmed.ncbi.nlm.nih.gov/30252293/1
- (n.d.). KEMSTRO (baclofen orally disintegrating tablets) label. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f133fe04-1550-4fa4-9dc4-652c27936bf212
- (January 2017). Oral Baclofen Withdrawal Resulting in Progressive Weakness and Sedation Requiring Intensive Care Admission. The Neurohospitalist, 7(1), 39–40. https://doi.org/10.1177/194187441663740412
- (June 2021). Toxicologic Confounders of Brain Death Determination: A Narrative Review. Neurocritical Care, 34(3), 1072–1089. https://doi.org/10.1007/s12028-020-01114-y1
- (June 1998). Baclofen overdose: drug experimentation in a group of adolescents. Pediatrics, 101(6), 1045–1048. https://doi.org/10.1542/peds.101.6.10451
- (26 October 2011). Baclofen toxicity in patients with advanced nephropathy: proposal for new labeling. American Journal of Nephrology, 34(6), 491–495. https://doi.org/10.1159/0003332471
- (Nov–Dec 2005). Delirium associated with baclofen withdrawal: a review of common presentations and management strategies. Psychosomatics, 46(6), 503–507. https://doi.org/10.1176/appi.psy.46.6.5031
- Ameisen O. (March-April 2005). Complete and prolonged suppression of symptoms and consequences of alcohol-dependence using high-dose baclofen: a self-case report of a physician. Alcohol and Alcoholism, 40(2), 147-150. https://pubmed.ncbi.nlm.nih.gov/15596425/1
- (n.d.). Baclofen. Chemistry World. https://www.chemistryworld.com/podcasts/baclofen/3010770.article12
- (October 2022). Baclofen in alcohol use disorder: An analysis of the data provided by the French 'Temporary Recommendation for Use' 2014–2017 cohort. Drug and Alcohol Dependence Reports. https://pmc.ncbi.nlm.nih.gov/articles/PMC9597083/1
- (January 2020). France Grants an Approval to Baclofen for Alcohol Dependence. Alcohol and Alcoholism, 55(1), 44. https://doi.org/10.1093/alcalc/agz07012
- (n.d.). Health Canada Drug Product Database. health-products.canada.ca. https://health-products.canada.ca/dpd-bdpp/index-eng.jsp1
- (2022). Baclofen in alcohol use disorder: An analysis of the data provided by the French "Temporary Recommendation for Use" 2014–2017 cohort. Frontiers in Psychiatry. https://doi.org/10.3389/fpsyt.2022.9497501
- (2020). Anlage 1 AMVV. https://www.gesetze-im-internet.de/amvv/anlage_1.html1
- (n.d.). Baclofen Medical Valley 10 mg tabletter – Bipacksedel (Swedish MPA patient information leaflet). Läkemedelsverket (Swedish Medical Products Agency). https://docetp.mpa.se/LMF/Baclofen%20Medical%20Valley%20tablet%20PL_09001bee80e7e67c.pdf1
- (n.d.). Federal Food, Drug, and Cosmetic Act; current DailyMed labeling. dailymed.nlm.nih.gov. https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=baclofen1
Automated synthesisInformation aggregated and synthesized using an autonomous workflow built by Josie Kins.
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