A COMPARISON OF SUBJECTIVE, PSYCHOMOTOR AND PHYSIOLOGICAL-EFFECTS OF A NOVEL MUSCARINIC ANALGESIC, LY297802 TARTRATE, AND ORAL MORPHINE IN OCCASIONAL DRUG-USERS

This study compared the subjective, physiological and psychomotor effe cts of a novel muscarinic analgesic (LY297802) and oral morphine in he althy volunteers. Nine, non-dependent, occasional drug users participa ted in nine experimental sessions in which they received the following conditions: placebo, 0.1, 0.3, 0.56 and 1 mg of oral LY297802 and 10, 30, 56 and 100 mg of oral morphine. Subjective drug effects were asse ssed using the Visual Analog Scale (VAS), the Addiction Research Cente r Inventory (ARCI) and subjective and objective agonist and antagonist scales of the Adjective Rating Scale (ARS). These measures were colle cted 30 min before and every 30 min post drug administration for a 4-h period. Psychomotor performance was evaluated using the Digit Symbol Substitution Test (DSST) at these same time intervals. Physiological m easures were collected continuously throughout the sessions. Oral morp hine produced significant increases in some subjective effects scales, including elevations on the VAS, ARCI and ARS. In contrast, LY297802 did not engender changes different from placebo on any of these indice s. Morphine produced significant dose-dependent effects in DSST perfor mance, heart rate, blood oxygen saturation and pupil diameter. LY29780 2 significantly and dose dependently increased heart rate, mean materi al pressure and diastolic blood pressure. These results suggest that L Y297802 does not induce subjective effects similar to morphine, but th at it has some significant physiological effects. (C) 1998 Elsevier Sc ience Ireland Ltd. All rights reserved.