Cross-tolerance

Cross-tolerance (pronunciation: /krɒsˈtɒlərəns/) is a pharmacological concept where the tolerance to the effects of a certain drug leads to tolerance to another drug, often of the same class.

Etymology

The term "cross-tolerance" is derived from the English words "cross," meaning to traverse or intersect, and "tolerance," which in pharmacology refers to the reduced response to a drug following repeated use.

Definition

Cross-tolerance is a phenomenon that occurs when the repeated exposure to one drug results in the reduced responsiveness not only to that drug but also to other drugs, typically within the same class. This can occur with various substances, including opioids, benzodiazepines, and alcohol.

Mechanism

The mechanism of cross-tolerance is often related to the downregulation or desensitization of receptors that are common to the drugs involved. For example, in the case of opioids, repeated use of one opioid can lead to a decrease in the number of mu-opioid receptors, resulting in reduced sensitivity to other opioids.

Clinical Significance

Cross-tolerance has significant implications in clinical practice. It can affect the efficacy of drug therapy, particularly in the treatment of conditions such as pain, anxiety, and addiction. Understanding cross-tolerance is crucial in avoiding potential drug interactions and in managing patients' medication regimens effectively.

Related Terms

Tolerance: A state of reduced responsiveness to a drug that is developed as a result of repeated exposure to the drug.
Drug interaction: A situation in which a substance affects the activity of a drug when both are administered together.
Pharmacodynamics: The study of the biochemical and physiological effects of drugs and their mechanisms of action.