Abstract
Sensitization is one of the main topics in the research of drugs of abuse. It is characterized - in contrast to tolerance - by increased reaction of the organism after the repeated administration of the same or different drug.
Sensitization seems to be one of the main causes of dependence and very often of relapse in ex-addicts. Sensitization is also being related with craving for a drug.
Research of both sensitization and cross-sensitization revealed some properties of addictive drugs, which were in the term of "classical concept" tolerance - withdrawal hidden. This review summarizes description of behavioral signs of sensitization in experimental models, its measurement and evaluation and provides a survey of drugs to which sensitization was observed.