Animal experimentation in studying addiction to the newer synthetic analgesics.

HE term addiction, when applied to the syndrome resulting from T the prolonged use of morphine and its congeners in man, by coinmon usage involves three principal components, psychic dependence, physical dependence, and acquired toleranee. In view of the fact that the newer synthetic analgesics produce pharmacological effects, many of which are qualitatively similar to those of morphine and its derivatives, it is assumed, for purposes of this discussion, that morphine should stand as the drug of comparison, and that information regarding these three not easily dissociable qualities which constitute addiction to morphine must be obtained for each new agent of this type before it may be safely used clinically. It is clear that clinical facilities for evaluating addiction liability are inadequate to keep pace with the rapid development of the newer synthetic analgesics. This being the case, and recognizing that the final evaluation of addiction liability of any compound proposed for clinical use must be determined in the human species, only that evidence which relates to the following question will be presented and discussed here: Does any infrahuman species exist which parallels normal man in its ability to develop “addiction“ when chronically poisoned with morphine, its congeners, and the newer synthetic analgesics, and, if so, is this parallelism sufficiently striking that this species could be used as a reliable test object for the preliminary scrcening of new compounds? Since comparatively little work has been done in this field with the newer analgesic agents, a large share of the following discussion must center about morphine.