DISCRIMINATIVE STIMULUS AND SUBJECTIVE EFFECTS OF OPIOIDS WITH MU-ACTIVITY AND KAPPA-ACTIVITY - DATA FROM LABORATORY-ANIMALS AND HUMAN-SUBJECTS

Although a large and rich body of data is available regarding the disc riminative stimulus effects of opioids in laboratory animals and human subjects, it has been difficult to reconcile the data obtained from t hese two different sources. Therefore, the purpose of this review is t o bring together data from both animal and human laboratories and syst ematically to compare the discriminative stimulus effects of opioids, in particular those with activity at both mu and kappa opioid receptor types (i.e., the mixed action opioids). The data that can be collecte d from laboratory animals differ from the data that can be collected i n human subjects, In general, the advantage of studies in laboratory a nimals is that they can investigate very broad dose ranges of opioids as well as some very selective opioids that are not available for inve stigation in human subjects, Although investigations in human subjects are limited by the compounds and doses available for examination,;he advantage of these studies is that they can examine the subjective as well as the discriminative stimulus effects of opioids. Taken together , studies conducted in laboratory animals and human subjects indicate that the mixed action opioids are best classified as intermediate effi cacy mu agonists with additional activity through other non-mlr, possi bly kappa opioid systems.