EFFECTS OF ACETYLMETHADOL ON MOTOR-ACTIVITY AND SCHEDULE-CONTROLLED RESPONDING

The effects of L-.alpha.-acetylmethadol (LAAM) on locomotor activity and operant behavior were examined in rats. LAAM increased locomotor activity when given i.p. at doses of 1 mg/kg and 3 mg/kg, but 10 mg/kg produced a slight decrease in motor activity over the 10 h period. The largest increases and decreases in locomotor activity occurred 6-8 h after drug administration. Other rats were trained to lever press for food pellets under a fixed-interval 90 s, fixed-ratio 10 response multiple schedule. LAAM only decreased rates of responding under the multiple schedule. Marked decreases in responding rates under both components of the schedule occurred when LAAM was administered i.p. either 3 or 6 h before the session at doses of 3 mg/kg and 10 mg/kg. The rate-decreasing effects of LAAM became greater the longer the interval between administration of the drug and initiation of the session. LAAM, a derivative of d-methadone, is currently being examined clinically as an alternative to methadone in the maintenance treatment of heroin addicts.