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

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


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Summary sheet: Meprobamate
Chemical Nomenclature
Common names Meprobamate, Miltown, Equanil
Systematic name [2-(carbamoyloxymethyl)-2-methyl-pentyl] carbamate
Class Membership
Psychoactive class Depressant
Chemical class Carbamate
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.

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.


Meprobamate, also known by the brand names Miltown and Equanil, is a carbamate sedative-hypnotic. Meprobamate has been used medically as a centrally-acting muscle relaxant, anxiolytic, antidepressant, analgesic and hypnotic for the short-term treatment of insomnia. Meprobamate produces similar effects to barbiturates. It is the active metabolite of carisoprodol, to which its effects are extremely similar.

Meprobamate, like carisoprodol and barbiturates, has been primarily replaced by benzodiazepines due to a larger therapeutic window, having less severe adverse effects and being physically safer in the case of overdose.

History and culture

Meprobamate was first synthesized by chemists Frank Berger and Bernard John Ludwig in 1950.[2] It was licensed by Wallace Laboratories as Miltown and marketed in 1955 as a minor tranquilizer (antidepressant/anxiolytic). It quickly became the first blockbuster drug and a mainstay of American popular culture, with one in three prescriptions at one point being for meprobamate.[3][4]

In 1965, the US ruled it to be a sedative rather than a tranquilizer.[5] Two years later, the US Food, Drugs, and Cosmetics Act was amended to require strict monitoring of the production, distribution, and prescription of meprobamate.[6] Three years later, it became a controlled substance. The advent of the benzodiazepines, which served most of the same purposes but have a more favorable safety profile, caused a long decline in the use of meprobamate.

In 2012, the EU removed all meprobamate-containing drugs from the European market.[7] A year later, Canada followed suit.[8]


Chemically, meprobamate is classified as a carbamate. It is extremely similar in structure to carisoprodol, the only difference being a primary amine in place of carisoprodol's secondary amine. Carbamates are derivatives of carbamic acid. The empirical formula of meprobamate is C9H18N2O4 and it has a molar mass of 218.250 grams per mole.


The precise mechanism of meprobamate is not completely understood. However it is believed that meprobamate acts similarly to benzodiazepines and barbiturates, acting as a positive allosteric modulator of a GABAA receptor[9]. Unlike barbiturates and benzodiazepines, in animal studies meprobamate has been shown to retain most of its effects without having gamma-aminobutyric acid present, which may also make meprobamate a direct agonist of the GABAA receptor[9]. Meprobamate has also been noted to be an adenosine reuptake inhibitor, making it unique among hypnotics[10].

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 ☠.

Physical effects

Visual effects

Cognitive effects

Experience reports

There are currently no anecdotal reports which describe the effects of this compound within our experience index.

Toxicity and harm potential

Meprobamate likely has moderate toxicity relative to dose. However, meprobamate is potentially lethal when mixed with depressants like alcohol or opioids. Meprobamate has been taken off the market in most countries such as Sweden and Indonesia due to side effects and abuse.

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

Tolerance and addiction potential

Meprobamate is extremely physically and psychologically addictive. Carbamate withdrawal, like barbiturate withdrawal, is medically serious and can potentially cause a life-threatening withdrawal syndrome that can cause seizures, psychosis, and death. Drugs which lower the seizure threshold such as tramadol and amphetamine should be avoided during withdrawal.

Tolerance will develop to the sedative-hypnotic effects of meprobamate after prolonged use. It is unknown exactly how long it takes for tolerance to reach baseline.

Dangerous interactions

Warning: Many psychoactive substances that are reasonably safe to use on their own can suddenly become dangerous and even life-threatening when combined with certain other substances. The following list provides some known dangerous interactions (although it is not guaranteed to include all of them).

Always conduct independent research (e.g. Google, DuckDuckGo, PubMed) to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions have been sourced from TripSit.

  • Depressants (1,4-Butanediol, 2M2B, alcohol, benzodiazepines, barbiturates, GHB/GBL, methaqualone, opioids) - This combination potentiates the muscle relaxation, amnesia, sedation, and respiratory depression caused by one another. At higher doses, it can lead to a sudden, unexpected loss of consciousness along with a dangerous amount of depressed respiration. There is also an increased risk of suffocating on one's vomit while unconscious. If nausea or vomiting occurs before a loss of consciousness, users should attempt to fall asleep in the recovery position or have a friend move them into it.
  • Dissociatives - This combination can unpredictably potentiate the amnesia, sedation, motor control loss and delusions that can be caused by each other. It may also result in a sudden loss of consciousness accompanied by a dangerous degree of respiratory depression. If nausea or vomiting occurs before consciousness is lost, users should attempt to fall asleep in the recovery position or have a friend move them into it.
  • Stimulants - 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

In most jurisdictions, meprobamate is considered a prescription-only and/or controlled drug.

  • Canada: Meprobamate is a Schedule IV drug in Canada. Additionally, Health Canada has withdrawn the substance from the market.[8]
  • Germany: Meprobamate is an authorized-only, unprescribable substance, in Anlage II.[11]
  • United States: In the United States, meprobamate is a Schedule IV Controlled Substance[12]. Therefore, it is prescription-only and anyone caught in possession of the substance with or without intent to distribute is punishable by law. In addition, it is no longer on the market, making prescriptions extremely unlikely.

External links


  1. Risks of Combining Depressants - TripSit 
  2. Ludwig BJ, Piech E (1951). "Some anticonvulsant agents derived from 1, 3-propanediol". J Am Chem Soc. 73 (12): 5779–5781. doi:10.1021/ja01156a086. 
  3. 1964-, Tone, Andrea (2009). The age of anxiety : a history of America's turbulent affair with tranquilizers. New York: Basic Books. ISBN 9780786727476. OCLC 302287405. 
  4. "Miltown: a game-changing drug you've probably never heard of | CBC Radio". CBC (in English). Retrieved 2018-09-22. 
  5. "MILTOWN OFF LIST OF TRANQUILIZERS; But It Will Continue to Be Used as a Sedative". The New York Times. 1965-04-22. Retrieved 2009-02-01. 
  6. "Tranquilizer Is Put Under U.S. Curbs; Side-Effects Noted". The New York Times. 1967-12-06. Retrieved 2009-02-01. 
  7. "Questions and answers on the suspension of the marketing uthorisations for oral meprobamate-containing medicines" (PDF). 2012-01-19. Retrieved 2012-01-20. 
  8. 8.0 8.1 "282 MEP (meprobamate-containing medicine) - Market Withdrawal, Effective October 28, 2013 - For Health Professionals". Health Canada. 
  9. 9.0 9.1 Barbiturate-Like Actions of the Propanediol Dicarbamates Felbamate and Meprobamate |
  10. A purinergic component in the central actions of meprobamate. |
  12. DEA Scheduled Drugs |