Methaqualone analogues, also known as qualones, are a group of 4-quinazolinone derivatives typified by the sedative and hypnotic drug methaqualone (former brand name Quaalude). They are known to act as GABAA receptor positive allosteric modulators to produce their effects.
Methaqualone itself was invented in the 1950s as an alternative to the older barbiturate class of sedatives. It has sedative/hypnotic and muscle relaxant effects and was sold mainly as a sleeping pill, but also as an anxiolytic. Methaqualone was widely prescribed during the 1960s and 1970s but was removed from sale following issues with substance abuse and addiction.
While it did have some safety advantages over barbiturates in terms of its acute potential for lethal overdose, methaqualone became known for its tendency to produce euphoria and aphrodisiac effects, and is also highly disinhibiting, with a large proportion of methaqualone associated fatalities due to traffic accidents following driving under the influence of methaqualone, or comparable fatal accidents. Unlike most sedative/hypnotic drugs, methaqualone and its relatives can also produce a paradoxical lowering of the seizure threshold, which causes complications with treatment of overdose because most anticonvulsant medications are also sedatives and so can be dangerous to combine with other sedative/hypnotic drugs. It is also powerfully synergistic with alcohol and is much more dangerous when mixed with alcohol than when consumed by itself.
Following the withdrawal of methaqualone from legitimate sale in the early 1980s, it fell out of use in most of the world, but has continued to be a widely used illicit drug in South Africa following its investigation as an incapacitating agent by the apartheid-era chemical weapons program Project Coast, which resulted in large quantities of surplus methaqualone being sold on the black market to finance covert operations, and its subsequent popularity led to continuing clandestine manufacture.
Methaqualone analogues reappeared as designer drugs in the late 1990s, with derivatives such as methylmethaqualone and etaqualone being sold particularly in Germany, and subsequently around the world, with additional derivatives continuing to appear. In the late 2010s and early 2020s, novel methaqualone analogues with at least 100-fold greater potency such as mephenaqualone emerged.
Table of qualones
Structure Name Chemical name PubChem CAS # Methaqualone 2-Methyl-3-(2-methylphenyl)-4-(3H)-quinazolinone 6292 72-44-6 Etaqualone 3-(2-ethylphenyl)-2-methyl-quinazolin-4-one 23914 7432-25-9 Ephinazone 2-ethyl-3-phenylquinazolin-4-one 719985 5260-41-3 B-151 Gujral ML, Saxena PN, Khauna BK. Potentiating effect of chlorpromazine hydrochloride on hypnosis induced by phenobarbitone and 2-ethyl-3-o-tolyl-4 (3H)-quinazolone. J. Indian Med. Prof. 1956; 3:1098-9. 2-ethyl-3-(2-methylphenyl)quinazolin-4-one 63117 1898-07-3 Methylmethaqualone 3-(2,4-dimethylphenyl)-2-methylquinazolin-4(3H)-one 63382 3244-75-5 Mecloqualone 3-(2-chlorophenyl)-2-methylquinazolin-4(3H)-one 9567 340-57-8 Mebroqualone 3-(2-bromophenyl)-2-methylquinazolin-4(3H)-one 364842 4260-20-2 Methoxyqualone 3-(2-methoxyphenyl)-2-methylquinazolin-4(3H)-one 365324 4260-28-0 Cloroqualone 3-(2,6-Dichlorophenyl)-2-ethyl-4-quinazolinone 63338 25509-07-3 Nitromethaqualone 2-methyl-3-(2-methoxy-4-nitrophenyl)-4(3H)-quinazolinone 63339 340-52-3 SL-164 (dicloqualone) 5-chloro-3-(4-chloro-2-methylphenyl)-2-methylquinazolin-4-one 63386 3476-88-8 HQ-355 2-(fluoromethyl)-3-(2-methylphenyl)quinazolin-4-one 63235 37107-06-5 Afloqualone 6-Amino-2-(fluoromethyl)-3-(2-methylphenyl)quinazolin-4-one 2040 56287-74-2 PPQ 2,3-diphenylquinazolin-4-one 248040 22686-82-4 PPTQ 3-(4-methylphenyl)-2-phenylquinazolin-4-one 722868 37856-14-7 Cl-PPQ 3-(2-chlorophenyl)-2-phenylquinazolin-4-one 722878 MCPPQ 8-Methyl-2-phenyl-3-(2-chlorophenyl)quinazolin-4-one Mephenaqualone450. Мефенаквалон (Mephenaqualone) Раздел I.A. Вещества с подтвержденной структурой 8-Methoxy-2-phenyl-3-(2-methylphenyl)quinazolin-4-one ZXW-1646 2-(2-chloro-4-methylphenyl)quinazoline-4(3h)-ketone compound and medical use thereof. Patent WO 2020/239050 7-Fluoro-2-(2-chloro-4-methylphenyl)-3-phenylquinazolin-4-one 155344735 Diproqualone 3-(2,3-dihydroxypropyl)-2-methyl-quinazolin-4-one 64112 36518-02-2
See also List of benzodiazepines
References