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Fatal overdose may occur when benzodiazepines are combined with other depressants such as opiates, barbiturates, gabapentinoids, thienodiazepines, alcohol or other GABAergic substances.[1]

It is strongly discouraged to combine these substances, particularly in common to heavy doses.


This page has not been approved by the PsychonautWiki administrators.

It may contain incorrect information, particularly with respect to dosage, duration, subjective effects, toxicity and other risks.

Summary sheet: Phenazepam
Chemical Nomenclature
Common names Phenazepam, Bromdihydrochlorphenylbenzodiazepine
Substitutive name Phenazepam
Systematic name 7-Bromo-5-(2-chlorophenyl)-1,3-dihydro-2H-1,4-benzodiazepin-2-one
Class Membership
Psychoactive class Depressant
Chemical class Benzodiazepine
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Threshold 0.5 mg
Light 1 - 2 mg
Common 2 - 3 mg
Strong 4 - 5 mg
Heavy 5 mg +
Total 15 - 24 hours
Onset 15 - 40 minutes
Peak - hours
Offset - hours
After effects 15 - 36 hours

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.

Phenazepam is a depressant substance of the benzodiazepine class. Notable effects include anxiety suppression, disinhibition, sedation, muscle relation, and amnesia. Phenazepam has the street names "Bonsai", "Soviet Benzo", "Fenaz", "Panda".

Sudden discontinuation of benzodiazepines can cause seizures (which may be life-threatening in certain cases[2]) for individuals who have been heavily using them for a prolonged period of time. For this reason, it is recommended to gradually lower the daily dose over a period of time instead of stopping abruptly — a technique known as tapering.[3]

History and culture

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Phenazepam is a drug of the benzodiazepine class. Benzodiazepine drugs contain a benzene ring fused to a diazepine ring, which is a seven membered ring with the two nitrogen constituents located at R1 and R4. The benzyl ring of phenazepam is substituted at R7 with a bromine group. Like most benzodiazepines, phenazepam has a phenyl ring in R5 which is substituted by chlorine in the R2' group. Phenazepam also contains an oxygen group double bonded to R2 of its diazepine ring to form a ketone. This oxygen substitution at R2 is shared with other benzodiazepine drugs with the suffix -azepam.

Like other benzodiazepines, phenazepam (7-bromo-5-(2-chlorophenyl)-1,3-dihydro-1,4-benzodiazepin-2-one) is composed of a benzene ring fused to a seven-membered 1,4-diazepine ring. A 2-chlorophenyl ring is attached at the 5-position and a bromine is attached at the 7-position. Phenazepam has a molecular formula of C15H10BrClN2O and a molecular weight of 349.6 g/mol.[4]


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This pharmacology section is incomplete.

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While the toxicity of phenazepam is relatively low in relation to dosage, it still carries the addiction, overdose, and withdrawal risks associated with benzodiazepines. Additionally, the drug is potent at one-tenth of the normal dose of diazepam. Higher doses of phenazepam are sometimes prescribed for severe anxiety or epileptic seizures.[5]

Phenazepam is an agonist of the gamma-aminobutyric acid-A (GABAA) receptor and produces CNS depression. In plus-maze and conflict tests in male rats, very low doses of phenazepam showed an anxiolytic effect. Phenazepam in conventional doses acts as a potent tranquilizer. Phenazepam has been shown to fully substitute for pentobarbital in adult rats trained to discriminate pentobarbital vs saline. In the antagonism tests, the discriminative effects of phenazepam were fully antagonized by the selective benzodiazepine antagonist flumazenil. Phenazepam has a half-life of up to 60 hours and onset of effects is approximately 2-3 hours following oral administration; due to this, there is a potential for users to re-dose prior to the observation of its effects. 3-Hydroxyphenazepam, a metabolite of phenazepam, is also a GABAA receptor agonist. This pharmacokinetic data suggests that phenazepam would have a high overdose potential.[6]

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), a research literature based on collected anecdotal reports and the personal experiences of PsychonautWiki contributors. As a result, they should be regarded with a healthy degree of skepticism. It is worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce a full spectrum of effects. Likewise, adverse effects become much more likely with higher doses and may include addiction, serious injury, or death ☠.

Physical effects

Paradoxical effects
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Cognitive effects

After effects
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Experience reports

There are currently no anecdotal reports which describe the effects of this compound within our experience index. Additional experience reports can be found here:

Toxicity and harm potential

Radar plot showing relative physical harm, social harm, and dependence of benzodiazepines in comparison to other drugs.[14]

Phenazepam likely has a low toxicity relative to dose.[15] However, it is potentially lethal when mixed with depressants like alcohol or opioids.

It is strongly recommended that one use harm reduction practices, such as volumetric dosing, when using this substance to ensure the administration of the intended dose.

Tolerance and addiction potential


This toxicity and harm potential section is a stub.

As a result, it may contain incomplete or even dangerously wrong information. You can help by expanding upon or correcting it.
Note: Always conduct independent research and use harm reduction practices if using this substance.

Benzodiazepines are known to be extremely physically and psychologically addictive.[citation needed]

Tolerance will develop to the sedative-hypnotic effects within a couple of days of continuous use.[16] After cessation, the tolerance returns to baseline in 7-14 days. Withdrawal symptoms or rebound symptoms may occur after ceasing one's usage abruptly following a few weeks or longer of steady dosing, and may necessitate a gradual dose reduction.[17][18]


Benzodiazepine overdose may occur with extremely high doses or, more commonly, when it is taken with other depressants. This risk is especially present with other GABAergic depressants, such as barbiturates and alcohol, since they work in a similar fashion but bind to distinct sites on the GABAA receptor, resulting in significant cross-potentiation.[citation needed]

Benzodiazepine overdose is a medical emergency that may lead to a coma, permanent brain injury or death if not treated promptly. Symptoms may include severe slurred speech, confusion, delusions, respiratory depression, and non-responsiveness. The user might seem like they are sleepwalking. The user is also more susceptible to consume more of the same or another substance due to their impaired judgement, which is typically not seen with other substances during overdose.

Benzodiazepine overdoses may be treated effectively in a hospital environment, with generally favorable outcomes. Care is primarily supportive in nature, although overdoses are sometimes treated with flumazenil, a GABAA antagonist[19] or additional procedures such as adrenaline injections if other substances are involved.[citation needed]

Discontinuation and withdrawal

Benzodiazepine discontinuation is notoriously difficult; it is potentially life-threatening for individuals using regularly to discontinue use without tapering their dose over a period of weeks. There is an increased risk of high blood pressure, seizures, and death.[20] Substances which lower the seizure threshold such as tramadol should be avoided during withdrawal.[citation needed] Abrupt discontinuation also causes rebound stimulation which presents as anxiety, insomnia and restlessness.[citation needed]

If one wishes to discontinue after a period of regular use, it is safest to reduce the dose each day by a very small amount for a couple of weeks until close to abstinence. If using a short half-life benzodiazepine such as alprazolam or etizolam, a longer acting variety such as diazepam or clonazepam can be substituted. Symptoms may still be present, but their severity will be reduced significantly.

For more information on tapering from benzodiazepines in a controlled manner, please see this guide. Small quantities of alcohol can also help to reduce the symptoms, but otherwise cannot be used as an effective tapering agent.

The duration and severity of withdrawal symptoms depend on a number of factors including the half-life of the substance used, tolerance and the duration of abuse. Major symptoms will usually start within just a few days after discontinuation and persist for around a week for shorter lasting benzodiazepines. Benzodiazepines with longer half-lives will exhibit withdrawal symptoms with a slow onset and extended duration.[citation needed]

Dangerous interactions

Although many psychoactive substances are reasonably safe to use on their own, they can suddenly become dangerous or even life-threatening when combined with other substances. The following list includes some known dangerous combinations (although it is not guaranteed to include all of them). Independent research (e.g. Google, DuckDuckGo) should always be conducted to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions have been sourced from TripSit.

  • Stimulants - It can be dangerous to combine depressants with stimulants due to the risk of accidental excessive intoxication. Stimulants mask the sedative effect of depressants, which is the main factor most people use to gauge their level of intoxication. Once the stimulant effects wear off, the effects of the depressant will significantly increase, leading to intensified disinhibition, motor control loss, and dangerous black-out states. This combination can also potentially result in severe dehydration if one's fluid intake is not closely monitored. If choosing to combine these substances, one should strictly limit themselves to a pre-set schedule of dosing only a certain amount per hour until a maximum threshold has been reached.

Legal status


This legality section is a stub.

As such, it may contain incomplete or wrong information. You can help by expanding it.

  • Russia: Phenazepam is only available through a prescription, and it is the only typical benzodiazepine drug, which is not listed in III schedule which means it is not strictly controllable by the law. The second and atypical benzodiazepine also availible with only prescription is Tofisopam.

See also

External links


  1. Risks of Combining Depressants (Tripsit) |
  2. A fatal case of benzodiazepine withdrawal. ( / NCBI) |
  3. Canadian Guideline for Safe and Effective Use of Opioids for Chronic Non-Cancer Pain - Appendix B-6: Benzodiazepine Tapering |
  7. Henriksen, O. (1998) ‘An overview of Benzodiazepines in seizure management’, Epilepsia, 39(SUPPL. 1), pp. 2–6. doi: 10.1111/j.1528-1157.1998.tb02601.x.
  8. | Saïas T, Gallarda T | Paradoxical aggressive reactions to benzodiazepine use: a review
  9. Paton C | Benzodiazepines and disinhibition: a review | Psychiatr Bull R Coll Psychiatr |
  10. Bond AJ | Drug-induced behavioural disinhibition: incidence, mechanisms and therapeutic implications | CNS Drugs
  11. Drummer OH | Benzodiazepines—effects on human performance and behavior | Forensic Sci Rev
  12. | Benzodiazepine Pharmacology and Central Nervous System–Mediated Effects
  13. Goyal, Sarita. "Drugs and Dreams." Indian Journal of Clinical Practice (n.d.): n. pag. Web. |
  14. Development of a rational scale to assess the harm of drugs of potential misuse (ScienceDirect) |
  15. Benzodiazepine metabolism: an analytical perspective ( / NCBI) |
  16. Principles and Practice of Psychopharmacotherapy |
  17. Clinical Pharmacology, Clinical Efficacy, and Behavioral Toxicity of Alprazolam: A Review of the Literature |
  18. The American Psychiatric Publishing Textbook of Substance Abuse Treatment |
  19. Amrein, R., Leishman, B., Bentzinger, C., & Roncari, G. (1987). Flumazenil in benzodiazepine antagonism. Medical Toxicology and Adverse Drug Experience, 2(6), 411-429. PMID: 8306565
  20. A fatal case of benzodiazepine withdrawal. ( / NCBI) |