Progressive-ratio schedules of drug delivery in the analysis of drug self-administration: a review

Psychopharmacology (Berl). 1998 Oct;139(3):169-84. doi: 10.1007/s002130050702.


Drugs, like other reinforcers, can vary in their relative abilities to support operant responding. Considerable research has been designed to obtain useful measures of a given drug's or dose's "reinforcing efficacy" and to identify the ways in which a variety of behavioral and pharmacological variables impact these measures. Progressive-ratio schedules of drug delivery generate an index of a drug's or dose's reinforcing efficacy (the breaking point) and are being used increasingly as tools in the analysis of drug self-administration. Progressive-ratio schedules of drug delivery have been used to characterize the effects of pretreatment drugs, lesions, drug deprivation, physical dependence, and repeated non-contingent drug exposure on breaking points. Behavioral factors, including food restriction and electric shock, and organismic factors, including gender and strain, have also been investigated using progressive-ratio schedules of drug delivery. To the extent that breaking points provide an index of reinforcing efficacy, these studies demonstrate that a wide range of variables can influence the reinforcing efficacy of self-administered drugs. The objectives of this review are to critique existing research themes, outline potential limitations of progressive-ratio procedures, and to suggest potentially fruitful uses of these procedures in future research.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Algorithms
  • Cocaine / administration & dosage
  • Dopamine Uptake Inhibitors / administration & dosage
  • Drug Administration Schedule*
  • Drug Delivery Systems*
  • Forecasting
  • Humans
  • Narcotics / administration & dosage
  • Reinforcement, Psychology
  • Self Administration*


  • Dopamine Uptake Inhibitors
  • Narcotics
  • Cocaine