Methaqualone RIA Structure versus Reactivity

Abstract

A B S T R A C TFourteen different methaqualone-related substances (substituted 2-methyl-3-phenyl-4-quinazolinones) were analyzed by radioimmunoassay (RIA) at several different concentrations. An attempt is made to relate structural differences to the affinity of the compounds for the Roche RIA methaqualone antibody. The effects of substituent placement on the 2-methyl-3-phenyl-4-quinazolinone molecule a r e studied. Addition of a group to the para-position of the 3-phenyl group increased affinity, but alteration of other key functional groups had a reverse effect. I N T R O D U C T I O NThe radioimmunoassay procedure for methaqualone was developed several years ago by Roche [ 11 and has been in use in our laboratory f o r about 2 years to analyze urine samples for the presence of methaqualone and/or its hydroxylated metabolites.The metabolism of methaqualone and the excretion of methaqualone and its hydroxylated metabolites has been studied [2]. The reactivity of these metabolites with the Roche antibody has been determined [3-61.We have sought to determine the reactivity of other methaqualonerelated drugs (substituted %methyl-3-phenyl-4-quinazolinones): ethinazone (Aolan), mecloqualone (Nubarene), and nitromethaqualone (Parnox) which are used in Europe [?']. 209