phenibut phenibut phenibut, sold under the brand names anvifen, fenibut, and noofen among others, is a central nervous system depressant with anxiolytic effects, and is used to treat anxiety, insomnia, and for a variety of other indications. it is usually taken by mouth as a tablet, but may be given intravenously. phenibutclinical datatrade namesanvifen, fenibut, noofen, othersother namesaminophenylbutyric acid; fenibut; fenigam; phenigam; phenybut; phenygam; phenylgamma; phenigama; phg; phgaba; β-phenyl-γ-aminobutyric acid; β-phenyl-gabaroutes ofadministrationcommon: by mouthuncommon: rectaldrug classgaba receptor agonist; gabapentinoidatc coden06bx22 (who) legal statuslegal status au: s9 (prohibited substance) us: unapproved "new drug" (as defined by 21 u.s. code § 321(p)(1)). use in dietary supplements, food, or medicine is unlawful; otherwise uncontrolled. ru: rx-only pharmacokinetic databioavailabilitywell-absorbed≥63% (250 mg)metabolismliver (minimal)metabolitesinactiveonset of actionoral: 2–4 hoursrectal: 20–30 minuteselimination half-life5.3 hours (250 mg)duration of action15–24 hours (1–3 g)excretionurine: 63% (unchanged)identifiers iupac name 4-amino-3-phenylbutanoic acid cas number1078-21-3 y 3060-41-1 (hydrochloride)pubchem cid14113chemspider13491 yuniit2m58d6la8keggd10509 ychemblchembl315818 ycomptox dashboard (epa)dtxsid70870838 echa infocard100.012.800 chemical and physical dataformulac10h13no2molar mass179.219 g·mol−13d model (jsmol)interactive imagemelting point253 °c (487 °f) smiles o=c(o)cc(c1ccccc1)cn inchi inchi=1s/c10h13no2/c11-7-9(6-10(12)13)8-4-2-1-3-5-8/h1-5,9h,6-7,11h2,(h,12,13) ykey:dafocgyvtaokaj-uhfffaoysa-n y (verify) side effects of phenibut include sedation, sleepiness, nausea, irritability, agitation, dizziness, and headache, among others. overdose of phenibut can produce marked central nervous system depression including unconsciousness. the medication is structurally related to the neurotransmitter γ-aminobutyric acid (gaba), and hence is a gaba analogue. phenibut is thought to act as a gabab receptor agonist, similarly to baclofen and γ-hydroxybutyrate (ghb). however, at low concentrations, phenibut mildly increases the concentration of dopamine in the brain, providing stimulatory effects in addition to the anxiolysis. phenibut was developed in the soviet union and was introduced for medical use in the 1960s. today, it is marketed for medical use in russia, ukraine, belarus, kazakhstan, and latvia. the medication is not approved for clinical use in the united states and most of europe, but it is also sold on the internet as a supplement and purported nootropic. phenibut has been used recreationally and can produce euphoria as well as addiction, dependence, and withdrawal. it is a controlled substance in australia, and it has been suggested that its legal status should be reconsidered in europe as well. medical uses phenibut is used in russia, ukraine, belarus and latvia as a pharmaceutical drug to treat anxiety and to improve sleep (e.g., in the treatment of insomnia). it is also used for various other indications, including the treatment of asthenia, depression, alcoholism, alcohol withdrawal syndrome, post-traumatic stress disorder, stuttering, tics, vestibular disorders, ménière's disease, dizziness, for the prevention of motion sickness, and for the prevention of anxiety before or after surgical procedures or painful diagnostic tests. available forms phenibut is available as a medication in the form of 250 mg or 500 mg tablets for oral administration and as a solution at a concentration of 10 mg/ml for infusion. in the us, dietary supplements labeled as containing phenibut have been found to contain zero to greater than 1,100 mg of phenibut per serving. contraindications contraindications of phenibut include: intolerance to phenibut pregnancy and breastfeeding children who are younger than two years of age liver insufficiency or failure ulcerative lesions of the gastrointestinal tract phenibut should not be combined with alcohol. side effects phenibut is generally well-tolerated. possible side effects may include sedation, somnolence, nausea, irritability, agitation, anxiety, dizziness, headache, and allergic reactions such as skin rash and itching. at high doses, motor incoordination, loss of balance, and hangovers may occur. due to its central nervous system depressant effects, people taking phenibut should refrain from potentially dangerous activities such as operating heavy machinery. with prolonged use of phenibut, particularly at high doses, the liver and blood should be monitored, due to risk of fatty liver disease and eosinophilia. overdose in overdose, phenibut can cause severe drowsiness, nausea, vomiting, eosinophilia, lowered blood pressure, renal impairment, and, above 7 grams, fatty liver degeneration. there are no specific antidotes for phenibut overdose. lethargy, somnolence, agitation, delirium, tonic–clonic seizures, reduced consciousness or unconsciousness, and unresponsiveness have been reported in recreational users who have overdosed. management of phenibut overdose includes activated charcoal, gastric lavage, induction of vomiting, and symptom-based treatment. there have been three associated deaths which found phenibut in the users system but only one of these cases single handedly included phenibut. dependency and withdrawal tolerance to phenibut easily develops with repeated use leading to dependency. withdrawal symptoms may occur upon discontinuation, and, in recreational users taking high doses, have been reported to include severe rebound anxiety, insomnia, anger, irritability, agitation, visual and auditory hallucinations, and acute psychosis. baclofen has successfully been used for treatment of phenibut dependence. interactions phenibut may mutually potentiate and extend the duration of the effects of other central nervous system depressants including anxiolytics, antipsychotics, sedatives, opioids, anticonvulsants, and alcohol. pharmacology