Reinforcement by orally delivered methadone, cocaine, and methadone-cocaine combinations in rhesus monkeys: are the combinations better reinforcers?
by
Wang NS, Brown VL, Grabowski J, Meisch RA.
Department of Psychiatry and Behavioral Sciences,
University of Texas-Houston Health Science Center,
77030-3497, USA
Psychopharmacology (Berl) 2001 Jun;156(1):63-72

ABSTRACT

RATIONALE: Polydrug abuse is a problem that has been infrequently examined. In the present study, drug self-administration procedures were used to investigate the reinforcing effects of drug combinations. OBJECTIVES: To determine the absolute and relative response rates maintained by orally delivered methadone, cocaine, and their combinations under sequential and concurrent access. Choice between drug combinations containing different concentrations of cocaine was also determined. METHODS: Oral intake of methadone, cocaine, and their combinations was studied with rhesus monkeys during daily 3-h sessions. Lip contact (the operant response) was reinforced by delivery of liquid contingent upon completion of a fixed-ratio schedule. In one series, the drugs and drug combinations were studied sequentially with the water vehicle concurrently available. In the next series, the drugs and drug combinations were concurrently available. In the third series, pairs of drug combinations containing different concentrations of cocaine were also concurrently available. RESULTS: Methadone, cocaine and their combinations functioned as reinforcers. Under sequential access, response rates for the drug combinations and the component drugs were often similar. However, under concurrent access, response rates for the drug combinations were greater than response rates for the component drugs at the highest FR size for each condition. Also, drug combinations containing higher cocaine concentrations were preferred to combinations containing lower cocaine concentrations. CONCLUSIONS: Combinations of methadone and cocaine have relatively greater reinforcing effects than the component drugs, and these greater reinforcing effects are better detected with concurrent measures than with sequential measures.

Pain
Fentanyl
Tramadol
Tolerance
LAAM v methadone
Methadone: structure
Opioids and depression
Methadone plus cocaine
Methadone maintenance
Rapid opioid detoxification
Methadone and cancer pain
Buprenorphine v methadone
Methadone, LAAM and the rush
Methadone for tramadol addicts?

Refs
and further reading

HOME
HedWeb
Nootropics
cocaine.wiki
Future Opioids
BLTC Research
MDMA/Ecstasy
Superhapiness?
Utopian Surgery?
The Abolitionist Project
The Hedonistic Imperative
The Reproductive Revolution
Critique of Huxley's Brave New World

The Good Drug Guide
The Responsible Parent's Guide
To Healthy Mood Boosters For All The Family