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

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

Summary sheet: Metizolam
Chemical Nomenclature
Common names Metizolam, Desmethyletizolam
Systematic name 4-(2-chlorophenyl)-2-ethyl-6H-thieno[3,2-f] [1,2,4]triazolo[4,3-a] [1,4]diazepine
Class Membership
Psychoactive class Depressant
Chemical class Thienodiazepine
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 < 1 mg
Light 1 - 2 mg
Common 2 - 4 mg
Strong 4 - 6 mg
Heavy 6 mg +
Total 5 - 8 hours
Onset 30 - 90 minutes
After effects 10 - 30 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.


Metizolam (also known as Desmethyletizolam) is a synthetic depressant of the thienodiazepine chemical class that reportedly produces etizolam-like effects such as anxiety suppression, disinhibition, sedation, muscle relaxation and memory suppression when administered. It is half as potent and has a 60% longer half-life than etizolam.[citation needed]

This compound was patented in 1995 by a Japanese company as a medication for treating anxiety.[2][3][4] Despite this, it has little to no history of human usage prior to its release as a grey area research chemical by online vendors in September 2015.[citation needed]

Similar to benzodiazepines, the sudden discontinuation of thienodiazepines can be potentially dangerous or life-threatening for individuals using regularly for extended periods of time, sometimes resulting in seizures or death. It is highly recommended to taper one's dose by gradually lowering the amount taken each day for a prolonged period of time instead of stopping abruptly.[5]


Metizolam, or desmethyletizolam, is the demethylated analogue of the closely related etizolam. It is a structural relative of benzodiazepines whereby the benzene ring has been replaced by a thiophene ring, classifying it as a thienodiazepine. It differs structurally from its parent compound etizolam through the removal of the methyl group on the triazole ring.

Metizolam contains a thiophene ring fused to a diazepine ring, which is a seven member ring with the two nitrogen constituents located at R1 and R4. Thiophene is a five member aromatic ring with one sulfur atom. This forms the thienodiazepine core of metizolam. An ethyl chain is bound to this bicyclic structure at R7.

Additionally, an R2 chlorine-substituted phenyl ring is bound to this structure at R5. Metizolam also contains a triazole ring fused to and incorporating R1 and R2 of its diazepine ring, classifying it as a thienotriazolodiazepine. Deschloroetizolam shares this fused triazole ring substitution with certain benzodiazepine substances, called triazolobenzodiazepines (distinguished by the suffix "-zolam").


Thienzodiazepines produce a variety of effects by binding to the benzodiazepine receptor site and magnifying the efficiency and effects of the neurotransmitter gamma aminobutyric acid (GABA) by acting on its receptors.[6] As this site is the most prolific inhibitory receptor set within the brain, its modulation results in the sedating (or calming effects) of metizolam on the nervous system.

Metizolam is absorbed fairly rapidly, with peak plasma levels achieved between 30 minutes and 2 hours. It has a mean elimination half life of about 3.4 hours. Metizolam acts as a full agonist at the benzodiazepine/GABAa receptor to produce its range of therapeutic and adverse effects.

Thienotriazolodiazepines are easily oxidized, rapidly metabolized, and have a lower risk of accumulation, even after prolonged treatment. Metizolam has a powerful anxiolytic action that is about 6 times greater than that of diazepam. At higher dosages, metizolam allows for a reduction in time taken to fall asleep, an increase in total sleep time, and a reduction in the number of awakenings. Metzolam has also shown some similar characteristics to tricyclic antidepressants.

Although Metizolam has certain potential benefits such as anxiety suppression and muscle rest, it should be administered with caution and in small doses because of its harm and abuse potential. Metizolam can be life-threatening if administered with other depressants, including alcohol and opiates.

The harm potential due to long-term usage and toxicity dosage levels of Metizolam are not yet clear since the substance has not been adequately studied and analyzed in a scientific context. This is simply because of the lack of a known history of human usage.

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Cognitive effects

Potentially dangerous interactions

Although many drugs are safe on their own, they can become dangerous and even life-threatening when combined with other substances. The list below contains some common potentially dangerous combinations, but may not include all of them. Certain combinations may be safe in low doses of each but still increase the potential risk of death. Independent research should always be done to ensure that a combination of two or more substances is safe before consumption.

  • Depressants (1,4-Butanediol, 2-methyl-2-butanol, alcohol, barbiturates, GHB/GBL, methaqualone, opioids) - This combination can result in dangerous or even fatal levels of respiratory depression. These substances potentiate the muscle relaxation, sedation and amnesia caused by one another and can lead to unexpected loss of consciousness at high doses. There is also an increased risk of vomiting during unconsciousness and death from the resulting suffocation. If this occurs, users should attempt to fall asleep in the recovery position or have a friend move them into it.
  • Dissociatives - This combination can result in an increased risk of vomiting during unconsciousness and death from the resulting suffocation. If this occurs, users should attempt to fall asleep in the recovery position or have a friend move them into it.
  • Stimulants - It is dangerous to combine thienzodiazepines with stimulants due to the risk of excessive intoxication. Stimulants decrease the sedative effect of benzodiazepines, which is the main factor most people consider when determining their level of intoxication. Once the stimulant wears off, the effects of thienzodiazepines will be significantly increased, leading to intensified disinhibition as well as other effects. If combined, one should strictly limit themselves to only dosing a certain amount of thienzodiazepines per hour. This combination can also potentially result in severe dehydration if hydration is not monitored.

Toxicity and harm potential

The toxicity and long-term health effects of recreational metizolam use have not been studied in any scientific context and the exact toxic dosage is unknown. This is because metizolam is a research chemical with very little history of human usage. Anecdotal evidence from people within the psychonaut community who have tried metizolam suggests that there are no negative health effects attributed to simply trying the substance by itself at low to moderate doses and using it very sparingly (but nothing can be completely guaranteed). Independent research should always be done to ensure that a combination of two or more substances is safe before consumption.

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

Lethal dosage

The lethal dosage of metizolam has not been established; however, (like many benzodiazepines) it has a large therapeutic index and margin of safety. Complications may arise when administered in excess as this compound has not been formally studied and has little to no history of human usage.

As with all GABAergic drugs, overdose can be lethal when mixed with other depressants including alcohol or opioids.

It is strongly recommended that one use harm reduction practices when using this substance.

Tolerance and addiction potential

Thienzodiazepines are extremely addictive. Tolerance to the sedative-hypnotic effects develops within a couple of days of repeated administration. After that, it takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption). Metizolam presents cross-tolerance with all thienzodiazepines and benzodiazepines, meaning that after the consumption of metizolam all compounds of the same class will have a reduced effect.

Abrupt discontinuation of metizolam following regular dosing over several days can result in a withdrawal phase which includes rebound symptoms such as increased anxiety and insomnia. It is possible to gradually reduce the dose over the course of several days, which will lengthen the duration of the withdrawal period, but reduce the perceived intensity.

Thienzodiazepine 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 seizure following discontinuation. Drugs which lower the seizure threshold such as tramadol should be avoided during withdrawal.


Thienodiazepine overdose may occur when a thienodiazepine is taken in extremely heavy quantities or concurrently with other depressants. This is particularly dangerous with other GABAergic depressants such as barbiturates and alcohol since they work in a similar fashion, but bind to distinct allosteric sites on the GABAA receptor. Thus their effects potentiate one another. Thienodiazepines increase the frequency in which the chlorine ion pore opens on the GABAA receptor while barbiturates increase the duration in which they are open, meaning when both are consumed, the ion pore will open more frequently and stay open longer.[7] Thienodiazepine overdose is a medical emergency that may lead to a coma, permanent brain injury or death if not treated promptly and properly.

Symptoms of a thienodiazepine overdose may include severe thought deceleration, slurred speech, confusion, delusions, respiratory depression, coma or death. Thienodiazepine overdoses may be treated effectively in a hospital environment, with generally favorable outcomes. Thienodiazepine overdoses are sometimes treated with flumazenil, a GABAA antagonist,[8] however care is primarily supportive in nature.

Paradoxical effects

Paradoxical reactions to benzodiazepines such as increased seizures (in epileptics), aggression, increased anxiety, violent behavior, loss of impulse control, irritability and suicidal behavior sometimes occur (although they are rare in the general population, with an incidence rate below 1%).[9][10]

These paradoxical effects occur with greater frequency in recreational abusers, individuals with mental disorders, children, and patients on high-dosage regimes.[11][12] Due to the close structural and pharmacological similarities they share, it is likely that these same risks apply to thienodiazepines as well.

Preparation methods

  • Volumetric liquid dosing - If one's thienodiazepines are in powder form, they are unlikely to weigh out accurately without the most expensive of scales due to their extreme potency. To avoid this, one can dissolve the thienodiazepine volumetrically into a solution and dose it accurately based upon the methodological instructions linked within this tutorial here.

Legal status


This legality section is a stub.

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

Metizolam is currently a grey area compound within most parts of the world. This means that it is not known to be specifically illegal within any country, but people may still be charged for its possession under certain circumstances such as under analogue laws and with intent to sell or consume.

  • Canada: All benzodiazepines are Schedule IV controlled substances in Canada.[13]
  • Germany: Metizolam is controlled under the NpSG (New Psychoactive Substances Act)[14] as of July 18, 2019.[15] Production and import with the aim to place it on the market, administration to another person and trading is punishable. Possession is illegal but not penalized.[16]
  • Sweden: Following its sale as a designer drug, metizolam was made illegal in Sweden on January 26, 2016.[17]
  • Switzerland: Metizolam is a controlled substance specifically named under Verzeichnis E.[18]
  • Turkey: Metizolam is a classed as drug and is illegal to possess, produce, supply, or import.[19]
  • United Kingdom: It is illegal to produce, supply, or import this drug under the Psychoactive Substance Act, which came into effect on May 26, 2016.[20]

See also

External links


  1. Risks of Combining Depressants - TripSit 
  2. Weber, K.-H., Bauer, A., Langbein, A., Daniel, H. (20 September 1978). "Heteroaromaten mit anellierten Siebenringen, III. Umwandlung von Thienotriazolooxazepinen in Diazepine". Justus Liebigs Annalen der Chemie. 1978 (8): 1257–1265. doi:10.1002/jlac.197819780806. ISSN 0075-4617. 
  3. Nakanishi, M., Tahara, T., Araki, K., Shiroki, M., Triazolothienodiazepine compounds 
  4. Kitajima, H., Ehara, S., Sato, H., Moriwaki, M., Onishi, K., Thienylazole compound and thienotriazolodiazepine compound 
  5. Kahan, M., Wilson, L., Mailis-Gagnon, A., Srivastava, A. (November 2011). "Canadian guideline for safe and effective use of opioids for chronic noncancer pain. Appendix B-6: Benzodiazepine Tapering". Canadian Family Physician. 57 (11): 1269–1276. ISSN 0008-350X. 
  6. Haefely, W. (29 June 1984). "Benzodiazepine interactions with GABA receptors". Neuroscience Letters. 47 (3): 201–206. doi:10.1016/0304-3940(84)90514-7. ISSN 0304-3940. 
  7. Twyman, R. E., Rogers, C. J., Macdonald, R. L. (March 1989). "Differential regulation of γ‐aminobutyric acid receptor channels by diazepam and phenobarbital". Annals of Neurology. 25 (3): 213–220. doi:10.1002/ana.410250302. ISSN 0364-5134. 
  8. Hoffman, E. J., Warren, E. W. (September 1993). "Flumazenil: a benzodiazepine antagonist". Clinical Pharmacy. 12 (9): 641–656; quiz 699–701. ISSN 0278-2677. 
  9. Mancuso, C. E., Tanzi, M. G., Gabay, M. (September 2004). "Paradoxical Reactions to Benzodiazepines: Literature Review and Treatment Options". Pharmacotherapy. 24 (9): 1177–1185. doi:10.1592/phco.24.13.1177.38089. ISSN 0277-0008. 
  10. Paton, C. (December 2002). "Benzodiazepines and disinhibition: a review". Psychiatric Bulletin. 26 (12): 460–462. doi:10.1192/pb.26.12.460. ISSN 0955-6036. 
  11. Bond, A. J. (1998). "Drug-Induced Behavioural Disinhibition: Incidence, Mechanisms and Therapeutic Implications". CNS Drugs. 9 (1): 41–57. doi:10.2165/00023210-199809010-00005. ISSN 1172-7047. 
  12. Drummer, O. H. (February 2002). "Benzodiazepines - Effects on Human Performance and Behavior". Forensic Science Review. 14 (1–2): 1–14. ISSN 1042-7201. 
  13. Branch, L. S. (2022), Consolidated federal laws of Canada, Controlled Drugs and Substances Act 
  14. "Anlage NpSG" (in German). Bundesministerium der Justiz und für Verbraucherschutz. Retrieved December 10, 2019. 
  15. "Verordnung zur Änderung der Anlage des Neue-psychoaktive-Stoffe-Gesetzes und von Anlagen des Betäubungsmittelgesetzes" (PDF). Bundesgesetzblatt Jahrgang 2019 Teil I Nr. 27 (in German). Bundesanzeiger Verlag. July 17, 2019. Retrieved December 28, 2019. 
  16. "§ 4 NpSG" (in German). Bundesministerium der Justiz und für Verbraucherschutz. Retrieved December 10, 2019. 
  17. (in Swedish) Folkhälsomyndigheten. |
  18. "Verordnung des EDI über die Verzeichnisse der Betäubungsmittel, psychotropen Stoffe, Vorläuferstoffe und Hilfschemikalien" (in German). Bundeskanzlei [Federal Chancellery of Switzerland]. Retrieved January 1, 2020. 
  19. "Karar Sayısı: 2016/9019" (PDF). Resmî Gazete, Sayı: 29790 (in Turkish). June 22, 2016. 
  20. Psychoactive Substances Act 2016