Phenazepam
Phenazepam is a benzodiazepine first developed in the Soviet Union in 1975.12 It is prescribed in Russia and other countries for psychiatric conditions including anxiety and schizophrenia, as well as for epilepsy, alcohol withdrawal, and surgical premedication.13 Phenazepam is notable for its exceptionally long duration of action and high potency.42 The substance has gained notoriety for problematic recreational use, with numerous reports of compulsive redosing and reckless behavior due to its subtle onset and extended effects.14
Contents
Dosage & Duration
Dosage
Duration
Subjective Effects
The experience is dominated by heavy sedation, anxiolysis, and physical relaxation, with no reported alteration of sensory perception. Coordination becomes unreliable, and at higher doses recall of the period following ingestion can be substantially impaired.
Physical
Muscle relaxation, drowsiness, and hypnotic sedation are the primary physical effects, accompanied by dizziness and loss of coordination.
Cognitive
Anxiety is reduced and the mental state is markedly sedated, with anterograde amnesia becoming pronounced as dose increases.
Reagent Testing
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Pharmacology
Pharmacodynamics
Phenazepam is a benzodiazepine that acts as a positive allosteric modulator at GABA-A receptors, enhancing the inhibitory effects of gamma-aminobutyric acid in the central nervous system.5 This mechanism produces anxiolytic, sedative, hypnotic, anticonvulsant, and muscle relaxant effects characteristic of the benzodiazepine class.6 The drug is notable for its high potency and prolonged duration of action compared to many other benzodiazepines.5
Pharmacokinetics
Phenazepam has an intermediate elimination half-life and produces active metabolites that contribute to its prolonged duration of action.5 The presence of these active metabolites means that effects and potential withdrawal symptoms may persist or emerge over an extended period following discontinuation. Blood concentrations during therapeutic use are typically less than 30 μg/L, though substantially higher concentrations have been observed in cases of impairment.
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.
Unsafe
AvoidThere is considerable risk of physical harm when taking these combinations, they should be avoided where possible.
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.
Harm Potential
Addiction & Dependence
Psychological
HighHigh abuse potential with significant risk of psychological dependence.9 Anecdotal reports indicate a notable suggestibility for compulsive redosing and reckless usage patterns, particularly due to the drug's subtle onset and amnestic effects.9
Physical
HighPhysical dependence develops with regular use, and treatment courses are typically limited to two weeks due to dependence risk.97 Abrupt discontinuation following prolonged use can cause severe withdrawal symptoms including restlessness, anxiety, insomnia, seizures, convulsions, and potentially death.107 Due to its intermediate half-life and active metabolites, withdrawal symptoms may take two or more days to manifest.9
Seizure Risk
Seizures and convulsions are documented withdrawal symptoms following abrupt discontinuation of prolonged use.107 Gradual dose reduction is necessary to prevent withdrawal-induced seizures.107
History & Culture
Phenazepam is a benzodiazepine that was first developed in the Soviet Union in 1975.9 The synthesis method was developed at the Physico-Chemical Institute of the Academy of Sciences of the Ukrainian SSR during the 1970s. The substance is now produced in Russia and several…
Legality
By Country
References
Source Pages
Citations
- (April 2012). Phenazepam: the drug that came in from the cold. Journal of Forensic and Legal Medicine, 19(3), 122–5. https://doi.org/10.1016/j.jflm.2011.12.014123
- (2012). New Uncontrolled Benzodiazepine, Phenazepam, Emerging Drug of Abuse. https://pmc.ncbi.nlm.nih.gov/articles/PMC3472894/12
- (n.d.). Phenazepam Pre-Review Report, Agenda item 5.8, Expert Committee on Drug Dependence. https://ecddrepository.org/en/phenazepam12
- (July 2012). Phenazepam abuse in Finland: Findings from apprehended drivers, post-mortem cases and police confiscations. Forensic Science International, 220(1–3), 111–7. https://doi.org/10.1016/j.forsciint.2012.02.00612
- (2001). Modulation of GABAA receptor-mediated currents by phenazepam and its metabolites. 364(1), 1-8. https://doi.org/10.1007/s0021001004031234
- (2023). GABA Receptor Positive Allosteric Modulators. https://www.ncbi.nlm.nih.gov/books/NBK554443/1
- (n.d.). Phenazepam 1 mg Tablets — Arpimed Prescribing Information. https://arpimed.am/phenazepam-1-mg-tablets/12345
- (n.d.). Addiction: Part I. Benzodiazepines — Side Effects, Abuse Risk and Alternatives. American Family Physician, April 2000.. https://www.aafp.org/pubs/afp/issues/2000/0401/p2121.html12
- (2015). Phenazepam Pre-Review Report, Agenda Item 5.8 — WHO Expert Committee on Drug Dependence, 37th Meeting. https://ecddrepository.org/sites/default/files/2023-04/5.8_phenazepam_prerev.pdf1234567
- (2018). Challenges of the pharmacological management of benzodiazepine withdrawal, dependence, and discontinuation — Fluyau et al., Therapeutic Advances in Psychopharmacology, 2018. https://doi.org/10.1177/2045125317753340123
- (June 2012). Phenazepam and cannabinomimetics sold as herbal highs in New Zealand. Drug Testing and Analysis, 4(6), 409–14. https://doi.org/10.1002/dta.3491
- (2011-06-30). Dunne: Health Ministry to recall Kronic brand — New Zealand Government press release. https://www.beehive.govt.nz/release/dunne-health-ministry-recall-kronic-brand1
- (n.d.). Феназепам® (0.5 мг) — MedElement Kazakhstan (РК-ЛС-5№013289). https://drugs2.medelement.com/drug/%D1%84%D0%B5%D0%BD%D0%B0%D0%B7%D0%B5%D0%BF%D0%B0%D0%BC-0.5%D0%BC%D0%B3-%D0%B8%D0%BD%D1%81%D1%82%D1%80%D1%83%D0%BA%D1%86%D0%B8%D1%8F/229733571477650962?instruction_lang=RU12
- (n.d.). Fenazepam Olainfarm Summary of Product Characteristics — Latvia State Agency of Medicines (99-0882). https://dati.zva.gov.lv/zalu-registrs/info/99-0882/smpc-w12
- (n.d.). Феназепам — Vidal.ru (Russian drug reference). https://www.vidal.ru/drugs/phenazepam12
Further Reading
Automated synthesisInformation aggregated and synthesized using an autonomous workflow built by Josie Kins.
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