Effects of passive immunization against morphine on heroin self-administration.

Antimorphine antibodies produced in Rhesus monkeys immunized with morphine-6-hemisuccinate-BSA were passively administered to recipient monkeys trained to self-administer heroin and cocaine. Following antibody administration, changes in heroin self-administration behavior were observed which were similar to those achieved with low doses of naloxone. Both manipulations increased heroin self-administration without affecting cocaine responding.