Blood levels in methaqualone in man following chronic therapeutic doses.

Human serum was analyzed for methaqualone (MTQ) and hydroxylated metabolites by gas liquid chromatographic (GLC), ultraviolet spectrophotometric (UV) and spectrofluorimetric (SF) procedures. Intact methaqualone was found to be the major circulating drug component after administration of multiple 300 mg daily doses over a 28-day period. Hydroxylated methaqualone metabolites, if present, were estimated to be in extremely low concentrations. After acute ingestion of large quantities of methaqualone (2.4-3.0 g), at least one methaqualone metabolite, [2-methyl-3-(2' hydroxymethylphenyl)-4(3H)-quinazolinone] was present in serum obtained from subjects with a history of chronic drug abuse.