Which drug is the most reinforcing? Comparison of heroin, cocaine, MDMA and nicotine by intravenous self-administration

2018 BPS Smith et al  IVSA Nicotine MDMA cocaine heroin

Intravenous self-administration (IVSA) is a robust model for the detection of reinforcing effects of centrally-acting drugs.  IVSA studies in the rat have been shown to translate well to drug abuse in humans, for wide variety of drugs of abuse. By using a fixed ratio (FR) schedule it is possible to determine whether a drug has reinforcing properties when compared to a non-reinforcer (in this case saline). However, by using a progressive ratio (PR) schedule it is possible to reliably compare the relative reinforcing efficacy of  different drugs using break-point testing. Four highly abused drugs, of differing legal status (heroin, cocaine, MDMA and nicotine), were compared for their relative reinforcing efficacy in rats.