A method was developed for measurement of toluene in blood and breath samples, using Tenax GC columns and a Bendix Flasher (Bendix Corp.) coupled to a flame ionization gas chromatograph. Blood samples were collected from six habitual toluene abusers during a 2-h abstinence period. Blood concentrations were found to range from 9.8 to 31.2 mg/L in samples taken shortly after inhaling. Blood half-lives of toluene were found to be much shorter in the first hour after inhalation (53.5 and 49.3 min) than in the second hour (79.3 and 111.2 min). In one of the subjects, blood:breath ratios were determined and averaged 18.2.

In two deaths of infants investigated by the Medical Examiner, high levels of dicyclomine were detected in blood. In one of the cases, a level of 0.505 micrograms/ml was found, nearly 10 times reported adult therapeutic blood concentrations, and death was ascribed to an overdose of dicyclomine. Gas chromatography/mass spectrometry was used for the analysis of biological specimens.

The desulfuration of thiopental to pentobarbital has previously been shown to be a relatively minor pathway of thiopental metabolism. In two cases, we observed significant conversion, resulting in blood pentobarbital concentrations up to 50 percent of total blood barbiturate (thiopental and pentobarbital) concentrations. Both patients received continuous infusions of thiopental and had present a condition (hypothermia) or drug (cimetidine) known to inhibit hepatic microsomal enzyme activity. It is suggested that inhibition of hepatic microsomal enzyme activity may prevent thiopental's metabolism to its major metabolite, a carboxylic acid analogue, and increase the amount of thiopental desulfurated to pentobarbital. Inhibition of hepatic microsomal metabolism also decreases the metabolism of pentobarbital. Until further elucidation of the causes of altered thiopental metabolism is available to identify patients more likely to have elevated concentrations of pentobarbital, monitoring of blood drug concentrations in patients receiving thiopental should include determination of both thiopental and pentobarbital concentrations.