Quinazolinones

Methaqualone and its analogues — mecloqualone, etaqualone, methylmethaqualone — built on a quinazolin-4-one core. They are GABA-A positive modulators acting at a site that is not the benzodiazepine site, so flumazenil does not reverse them, while cross-tolerance with the rest of this subject still applies. The sedation is closer to a barbiturate's than a benzodiazepine's, and so is the margin.

Medical use ended almost everywhere once the dependence and overdose record accumulated, and no reference product survives, so material sold under the old trade names is of unknown identity — substitution with other sedatives is the norm rather than the exception, and the substitutes are not equivalent. The analogues are not interchangeable with the parent either: the methylated one is reported to be convulsant, which methaqualone is not. Respiratory depression, particularly in combination, is how this family kills.