Biochemorphic Aspects of Paraldehyde and Certain Acetals. 20

Abstract

Paraldehyde has many features recommending it as a hypnotic agent. Conversations with Prof. C. W. Muehlberger and the late Prof. A. S. Loevenhart suggested a preliminary survey, at least, of the biochemorphology of paraldehyde and chemically related substances in the effort to determine whether or not there might be promise of finding a compound in the series with properties approaching more closely to those of an ideal clinical soporific. The compounds so far secured have been studied before, 1 but separately and not as a series. Acetal and methylal received clinical trial but were considered unsatisfactory. 2

In Table I is a list of the compounds we investigated, with their structural formulae, certain physical characteristics, and toxicity data. The latter were obtained by administration to rabbits by stomach tube of dilute water emulsions of the respective substances. Table II is a summary of the comparative depressant action of these aldehyde derivatives as determined in 150 experiments on rabbits, in which observations were made and recorded by methods modified from those described by Magnus. 3

These related compounds have equal rapidity and duration of action when given in doses of equal effectiveness. They are all excreted by the lungs in considerable amounts. Peripheral vasodilatation and increased heart rate are produced by all of them, but their effect on pupil size is inconstant. As may be seen from the summary data presented in Table II, none of these agents is particularly analgesic in action.

Some conclusions can be drawn concerning the biochemorphic† aspects of these substances. Very striking is the difference in the effect of lengthening the carbon chain on the central, and on the terminal carbon atoms.