John Wyeth & Brother Ltd.

A polarographic method has been developed for the determination of an antidepressant, 10-(m-chlorophenyl)-2,3,4,10-tetrahydropyrimido [1, 2a] indol-10-ol hydrochloride. The method is not subject to interference from the immediate precursor in the synthetic route of drug preparation or the products of thermal degradation of the active drug substance. The method may be used to monitor storage stability studies.

Changes of ultraviolet absorption spectra with pH in solution were used to determine pKa values for six 1,4-benzodiazepines. Diazepam, chlordiazepoxide and medazepam as a result of protonation of the molecule in acidic solutions, were found to each have one pKa, while two pKa values were observed for oxazepam, nitrazepam and lorazepam, because of protonation in acid and deprotonation of the neutral molecule in alkaline media. The spectra are explained by considering them to be superimposed spectra of the two benzene rings, one mono-substituted and one tri-substituted, within the molecule. Sites of protonation (principally at nitrogen atoms in position 4 in the diazepine ring) and deprotonation (for oxazepam, nitrazepam and lorazepam) are predicted and the differences in the observed pKa values explained.

From the temperature rise in individual mice it was possible to predict with reasonable accuracy whether or not a particular animal would die following an intraperitoneal injection of amphetamine below 100 mg./kg.All of the mice survived when their rectal temperature remained below 41.8°.In contrast, with one exception, all mice whose temperature rose above 42.4° died.The results indicated that hyperpyrexia was probably an important factor contributing to the increased toxicity of amphetamine to aggregated mice.Although doses of amphetamine approximating the L.D.₅₀ increased the body temperature of the isolated mice, the rectal temperature did not rise above 41.8° in any of the animals.