What is the definition of tachyphylaxis?

Tachyphylaxis refers to an acute and rapid decrease in the response to a drug after repeated doses over a short period of time. It signifies the body's quick adaptation to the presence of a drug, leading to a diminished effect even when the drug is administered at the same dosage. This phenomenon is particularly important in the context of local anesthetics and other pharmacological agents, as it can influence the effectiveness of a drug after initial exposure.

In contrast, while options related to buffer solution pH or the decreased potency of anesthetics in acidic tissues touch on relevant concepts in pharmacology and anesthesiology, they do not define tachyphylaxis. Similarly, the study of drug actions in the body describes pharmacodynamics in general but does not specify the rapid adaptation characteristic of tachyphylaxis. Thus, the core concept of increased tolerance to a drug captures the essence of tachyphylaxis, which explains why this option is correct.