Cyclic metabolites of etidocaine in humans

Metabolism of tocainide in the rat

The metabolism of tocainide, an oral antiarrhythmic agent, was studied in male Wistar rats following oral administration of 15 mg/kg of tocainide hydrochloride. Qualitative and quantitative identification of the metabolites in urine was carried out by GC-mass spectrometry and electron capture detector gas chromatography. About 15-20% of the dose administered was excreted as intact drug in the urine. An additional 20% of the dose was present as acid hydrolysable conjugates. Enzymatic hydrolysis (beta-glucuronidase) revealed half of the acid hydrolysable conjugates to be a glucuronide. The enzyme mediated hydrolysis was blocked by its specific inhibitor saccharo-1,4-lactone. N-acetyl tocainide, an oxidatively deaminated tocainide, an aldehyde adduct of tocainide, and a cyclic hydantoin derivative of tocainide were also identified as metabolites in the urine samples.

Leaching of 2-(2-hydroxyethylmercapto) benzothiazole into contents of disposable syringes

A contaminant was found to leach into the contents of two brands of disposable syringes. It was identified as 2-(2-hydroxyethylmercapto) benzothiazole and is believed to be formed during manufacture of the syringes as a result of a reaction between 2-mercaptobenzothiazole, a rubber vulcanization accelerator, and ethylene oxide, used for sterilization. The contaminant was isolated form the rubber plunger-seal and identified using mass, NMR, and UV spectroscopic methods. The amount of contaminant appearing in the contents of syringes was measured; up to 140 micro g was found under clinically relevant conditions. This finding has important implications with respect to the use of these syringes for drug administration and for the collection of blood for drug analyses.

3-(2,6-Xylyl)-5-methylhydantoin--a metabolite or a metabonate of tocainide in rats

1. G.1.c.-mass spectrometric analysis of urine extracts from rats dosed with tocainide (I) revealed the presence of cyclic compound identified as 3-(2,6-xylyl)-5-methylhydantoin (IV) derived from tocainide. 2. Evidence indicates that IV is derived from a conjugate of tocainide (tocainide carbonyl O-beta-D-glucuronide) (III) in humans. 3. Results of the present study indicate that in addition to being formed from a conjugate, IV is generated directly from tocainide in vivo in rats. Possible mechanisms for the formation of IV in rats in vivo are discussed.

The identification of eight hydroxylated metabolites of etidocaine by chemical ionization mass spectrometry

1. Eight hydroxylated metabolites of etidocaine have been identified in urine of man by g.l.c.-chemical ionization mass spectrometry, using methane and a mixture of methane and deuterium oxide as reactant gases. 2. The metabolites identified were N-(2,6-dimethyl-3- and 4-hydroxyphenyl-)-2-(N,N-ethylpropylamino)butyramides, N-(2,6-dimethyl-3- and 4-hydroxyphenyl)-2-aminobutyramides, N-(2,6-dimethyl-3- and 4-hydroxyphenyl)-2-(N-ethylamino)butyramides, and N-(2,6-dimethyl-3- and 4-hydroxyphenyl)-2-(N-propylamino)butyramides. 3. The eight metabolites represent about 10% of the oral dose of etidocaine.