Methaqualone (Quaaludes)

Methaqualone was introduced as a supposedly safer alternative to barbiturates for treating insomnia and anxiety, and became one of the most heavily abused recreational drugs of the 1970s ('disco biscuits'). Escalating misuse led the U.S. to tighten its control — first to Schedule II in 1973, then to Schedule I in 1984, ending legal manufacture and prescription. It is no longer available as a pharmaceutical in the U.S., but is still manufactured illicitly in parts of Africa and Asia, notably as 'mandrax' (often combined with cannabis in a preparation called 'white pipe'), where it remains a significant public-health concern.

Methaqualone is a central-nervous-system depressant that acts as a positive allosteric modulator of the GABA-A receptor, the brain's main inhibitory neurotransmitter-gated channel. Unusually, it does not bind the same sites as benzodiazepines or barbiturates; research using cryo-electron microscopy locates its action at a transmembrane subunit interface overlapping the site of general anesthetics such as etomidate. By enhancing GABA-driven inhibition it slows brain activity, producing relaxation, drowsiness, and euphoria, with progressively deeper depression of the nervous system at higher doses.

Users historically reported intense relaxation, euphoria, a sense of well-being, and reduced anxiety, along with impaired coordination, slurred speech, and numbness — effects often likened to a combination of alcohol intoxication and sedation. Tolerance develops quickly, pushing users toward higher doses. Because the drug is now produced only illicitly, anything sold as a 'Quaalude' today has no quality control and may contain unknown or more dangerous substances entirely.

Methaqualone has a narrow therapeutic index — the gap between an intoxicating dose and a dangerous one is small — and overdose can cause respiratory depression, coma, and death, with a particularly high risk when combined with alcohol or other CNS depressants. Unlike some barbiturate overdoses, severe methaqualone toxicity has also been reported to cause muscle spasms, convulsions, and involuntary movements. Regular use produces tolerance and physical dependence, and abrupt discontinuation can produce a dangerous withdrawal syndrome. Because all current supply is illicit, adulteration — including with far more potent substances — is a major additional hazard.