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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.

Summary sheet: Methaqualone
Chemical Nomenclature
Common names Methaqualone, Quaaludes, Ludes, Mandrax, Sopor, Quack, Vitamin Q, Soaper
Substitutive name Methaqualone
Systematic name 2-Methyl-3-(2-methylphenyl)-4(3H)-quinazolinone
Class Membership
Psychoactive class Depressant
Chemical class Quinazolinone
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 50 mg
Light 50 - 100 mg
Common 100 - 200 mg
Strong 200 - 300 mg
Heavy 300 mg +
Total 1 - 2 hours
Threshold 75 - 150 mg
Light 150 - 300 mg
Common 300 - 500 mg
Strong 500 - 600 mg
Heavy 600 mg +
Total 5 - 8 hours
Onset 30 minutes
Come up 30 minutes
Peak 2 - 4 hours
Offset 2 - 4 hours
After effects 6 - 8 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.


Methaqualone (brand name Quaalude in the US and Mandrax in the UK) is a central nervous system (CNS) depressant of the quinazolinone class that acts as a sedative and hypnotic. The sedative–hypnotic activity of methaqualone was first noted by researchers in the 1950s and in 1962 methaqualone itself was patented in the US by Wallace and Tiernan.[2] Its use peaked in the early 1970s as a hypnotic, for the treatment of insomnia, and as a sedative and muscle relaxant. It is still produced and used clandestinely as a recreational drug throughout the world. The drug was popular in the 1970s with hippies and in the disco club scene, known as ludes (from "quaaludes") or disco biscuits.


Methaqualone, or 2-methyl-3-(2-methylphenyl)-4(3H)-quinazolinone, is a compound of the quinazolinone class. Quinazolinone is a bicyclic structure containing a phenyl ring bound to another six-membered ring with two nitrogen members and a ketone group bound to R4. In methaqualone, this structure is substituted at R2 with a methyl group. Additionally, methaqualone contains a phenyl ring with a methyl group bound to R2 which is attached to the quinazolinone structure at R3.

Methaqualone is also known as 3,4-dihydro-2-methyl-4-oxo-3-o-tolylquinazoline, 2-methyl-3-(2-methylphenyl)-4-(3H)-quinazolinone, Metholquizolone, QZ-2, 2-Methyl-3-o-tolyl-4(3H)-quinazolinone, RIC-272, TR-495 and Quaalude. The Methaqualone LD50 for mice is 1250 mg/kg, and for rats both the values 255 and 326 mg/kg has been published. A common human dose (as sedative) is 150 mg for a 75 kg person.[3]


Despite prior speculation, a 2015 study demonstrates that methaqualone exhibits distinct functional properties at the GABA receptor sites compared with other allosteric modulators, and it mediates these through a different mechanism than the barbiturates and benzodiazepines that it historically has been lumped together with.[4] These distinctions could contribute to the reported differences in the in vivo effects induced by methaqualone and classic CNS depressants. In any case, the multifaceted functionality of methaqualone at GABAA receptors seems to be at the root of its clinical efficacy, as well as the addiction liability and recreational use associated with the drug.[4]

Methaqualone is a member of the class of quinazolines that is quinazolin-4-one substituted at positions 2 and 3 by methyl and o-tolyl groups respectively. A depressant that increases the activity of the GABA receptors in the brain and nervous system, it is used as a sedative and hypnotic medication. It has a role as a GABA agonist and a sedative.[5]

It could be speculated that despite differences in targeted receptors, methaqualone essentially produces a variety of effects by binding to its receptor sites and magnifying the efficiency and effects of the neurotransmitter gamma aminobutyric acid (GABA) by acting on its receptors. As this site is the most prolific inhibitory receptor set within the brain, its modulation would explain the resulting sedating or calming effects which ensue.

Although some early research indicated it may operate at the benzodiazepine receptor site, this doesn’t appear to be the case. More recent evaluations have pointed to a different GABAA modulatory site located on the transmembrane b(+)/a(-) subunit interface.

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

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

Independent research should always be done to ensure that a combination of two or more substances is safe before consumption.

Overdose of methaqualone can lead to seizures, coma or death. Taking doses of over 300mg can be dangerous for first time users. Depending on the state of the user's individual tolerance, doses of about 8,000mg per day can be fatal whilst others on even higher doses (of up to 20,000mg) may survive.

Although the exact lethal dosage of methaqualone has not been formally established, like many depressants, it is safe at appropriate dosages. Complications may arise when administered in excess or in combination with other depressants.

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

Quaaludes that are sold only for illicit recreational use now are synthesized in illegal laboratories. Illegally produced Quaaludes can contain other central nervous system depressants such as benzodiazepines or even fentanyl.

Tolerance and addiction potential

Methaqualone is 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). Methaqualone presents cross-tolerance with all gabaergic depressants, meaning that after the consumption of methaqualone all compounds of the same class will have a reduced effect.

Abrupt discontinuation of methaqualone 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.

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

  • Australia: Methaqualone is Schedule 9 in Australia, meaning it is illegal without a license and deemed to have no medical value.[citation needed]
  • Austria: Methaqualone is illegal to possess, produce and sell under the SMG (Suchtmittelgesetz Österreich).[citation needed]
  • Canada: Methaqualone is Schedule III in Canada, meaning it requires a prescription or license to legally possess.[citation needed]
  • Germany: Methaqualone is controlled under BtMG Anlage II, making it illegal to manufacture, import, possess, sell, or transfer it without a license.[6]
  • Switzerland: Methaqualone is a controlled substance specifically named under Verzeichnis A. Medicinal use is permitted.[7]
  • United Kingdom: Methaqualone is a Class B drug.[8]
  • United States: Methaqualone is a Schedule I drug, and is illegal to possess without a license.[9]

See also

External links


  1. Risks of Combining Depressants - TripSit 
  2. Vithal, S. B., Campanella, L. A., Hays, E. E., Hydroxy and alkoxy aryl quinazolinones 
  3. Methaqualone (Quaalude) Synthesis - [] 
  4. 4.0 4.1 Hammer, H., Bader, B. M., Ehnert, C., Bundgaard, C., Bunch, L., Hoestgaard-Jensen, K., Schroeder, O. H.-U., Bastlund, J. F., Gramowski-Voß, A., Jensen, A. A. (August 2015). "A Multifaceted GABAA Receptor Modulator: Functional Properties and Mechanism of Action of the Sedative-Hypnotic and Recreational Drug Methaqualone (Quaalude)". Molecular Pharmacology. 88 (2): 401–420. doi:10.1124/mol.115.099291. ISSN 1521-0111. 
  5. methaqualone (CHEBI:6821) 
  6. Anlage II BtMG - Einzelnorm 
  7. "Verordnung des EDI über die Verzeichnisse der Betäubungsmittel, psychotropen Stoffe, Vorläuferstoffe und Hilfschemikalien" (in German). Bundeskanzlei [Federal Chancellery of Switzerland]. Retrieved January 1, 2020. 
  8. Participation, E., Misuse of Drugs Act 1971