When tolerance for one drug extends to another drug within the same pharmaceutical class, what is this called?

Cross-tolerance refers to the phenomenon where tolerance to the effects of one drug also leads to a reduced response to another drug that is chemically or pharmacologically similar, typically within the same class of substances. This occurs because the body has adapted to the presence of the first drug, making the same mechanisms—such as enzyme induction or receptor downregulation—less effective when a second drug that acts on similar pathways is introduced.

For instance, if an individual has developed tolerance to alcohol, they may find that they require higher doses of benzodiazepines, which act similarly in the brain. This is important in social work practice, as it helps professionals understand the complexities of addiction and the interactions between different substances a client may be using.

In this context, cumulative tolerance, sequential tolerance, and rebound tolerance do not accurately describe the transfer of tolerance between different drugs within the same class. Cumulative tolerance refers more to the increasing tolerance to the same drug over time, sequential tolerance involves a staged approach to tolerance development, and rebound tolerance is characterized by an increase in sensitivity to a drug following its withdrawal. Hence, the correct term for the situation described is cross-tolerance.