PHARMACODYNAMIC AND METABOLIC INTERACTIONS BETWEEN ETHANOL AND 2 INDUSTRIAL SOLVENTS (METHYL N-BUTYL KETONE AND METHYL ISOBUTYL KETONE) ANDTHEIR PRINCIPAL METABOLITES IN MICE

MnBK and MiBK prolong the duration of ketamine-, pentobarbital-, thiop ental- and ethanol-induced loss of righting reflex (LRR) in mice. In e quimolar doses, (5 mmol/kg i.p.), both isomers were equipotent with re spect to the enhancement of ketamine-, pentobarbital-, and thiopental- induced LRR. However, MnBK was significantly more effective (twice as effective) than its isomer with respect to enhancing ethanol-induced L RR. An attempt to explain the difference in effectiveness between the two isomers was carried out. The effects of both ketones and their pri ncipal metabolites, (2-hexanol (2-HOL), 2,5-hexanedione (2,5-HD), 4-me thyl-2-pentanol (4-MPOL) and 4-hydroxy 4-methyl-2-pentanone (HMP)) on ethanol-induced LRR and ethanol elimination were studied in mice. The ketones and their metabolites were dissolved in corn oil and injected intraperitoneally 30 min before 4 g/kg ethanol for LRR and 2 g/kg for ethanol elimination. Ethanol-induced LRR was significantly prolonged b y the following dosages (mmol/kg), MnBK, 5; MiBK, 5; 2-HOL, 2.5; 4-MPO L, 2.5; and HMP, 2.5; 2,5-HD, 2.5, however exerted no effect. Concentr ations of ethanol in blood or brain upon return of the righting reflex were similar in solvent-treated and control animals. The mean elimina tion rate of ethanol was slower in groups pretreated with MnBK or 2-HO L as compared to control animals. Ethanol elimination in animals pretr eated with MiBK, HMP, 4-MPOL, or 2,5-HD was similar to that in control animals. These ketones are known to have some central depressant acti on on their own. This by itself could lead to prolongation of ethanol- induced LRR. However, MnBK, as well as one of its principal metabolite s, (2-HOL), markedly reduced ethanol elimination. This could explain t he observation that MnBK has a greater potentiating effect on ethanol- induced LRR that its isomer, MiBK, which does not affect ethanol elimi nation.