Tolerance

Slovak term: Slovenský termín

1. A decrease in response to a drug dose that occurs with continued use (WHO 2009).

Explanation

If an individual is tolerant to a drug, increased doses are required to achieve the effects originally produced by lower doses. Both physiological and psychosocial factors may contribute to the development of tolerance (WHO 2009).

Tolerance is one of the criteria of dependence syndrome (WHO 2009).

Example

Physiological factors include metabolic and functional tolerance. In metabolic tolerance, the body can eliminate the substance more readily, because the substance is metabolized at an increased rate. In functional tolerance, the central nervous system is less sensitive to the substance. An example of a psychosocial factor contributing to tolerance is behavioural tolerance, where learning or altered environmental constraints change the affect of the drug.

Acute tolerance refers to rapid, temporary accommodation to the effect of a substance following a single dose.

Reverse tolerance, also known as sensitization, refers to a condition where the response to a substance increases with repeated use (WHO 2009).

References

• WHO (2009) Guidelines for the Psychosocially Assisted Pharmacological Treatment of Opioid Dependence

Links

• WHO — The Health and Environment Lexicon