Which term refers to decreased response to a drug after its repeated usage?

The term that refers to decreased response to a drug after its repeated usage is tachyphylaxis. This phenomenon occurs when the body becomes less responsive to a medication due to prolonged exposure, leading to a diminished effect even as the same or increased doses are administered. This can occur with various drug classes and is particularly relevant in the context of dependence on certain medications, such as opioids. Understanding tachyphylaxis is crucial for healthcare professionals when administering local anesthesia or any other medication, as it may influence dosing strategies and patient outcomes.

The other terms listed do not describe this specific phenomenon. Drug intolerance usually refers to an adverse reaction or sensitivity to a substance where the normal dose produces unpleasant symptoms rather than diminishing effectiveness. Tachypnea relates to rapid breathing and does not pertain to drug response. Hypersensitivity is an exaggerated reaction of the immune system to a substance, indicating an increase in response rather than a decrease.