Toxic interactions of stimulants, narcotics and narcotic antagonists.

This study examines the lethality of combinations of central nervous system stimulants, narcotics and narcotic antagonists in rodents housed individually. The lethality of mice and rats from d-amphetamine was potentiated by methadone, cyclazocine and morphine, in that order of potency. Naloxone did not enhance lethality from d-amphetamine in mice, whereas it did antagonize lethality from morphine-d-amphetamine interactions. Naloxone did slightly enhance lethality from d-amphetamine in rats, but at a higher dose than those found to antagonize the lethality from morphine-d-amphetamine combinations. Methadone also enhanced the lethality from cocaine. These results have important implications for drug abusers and for patients being treated for narcotic addiction with either a methadone maintenance program or a cyclazocine administration program.