What describes an unexpected and uncommon effect that develops after administration of a drug?

What describes an unexpected and uncommon effect that develops after administration of a drug?

• A. Side effect
• B. Idiosyncratic action
• C. Tolerance
• D. Dependence

Answer: (B)

An idiosyncratic reaction is an unusual, unpredictable drug response that occurs in a small subset of people and is not related to the dose or the drug’s normal pharmacology. These reactions are not anticipated from typical drug effects and often arise from genetic, metabolic, or immune factors that make certain individuals react differently. That fits the idea of an unexpected and uncommon effect after administration. In contrast, a side effect is a predictable, often dose-related effect that accompanies therapy and is understood from the drug’s usual action. Tolerance refers to a diminished response with repeated dosing, requiring higher amounts for the same effect. Dependence involves physiological adaptation such that withdrawal occurs if the drug is stopped. These concepts describe more predictable or gradual processes, not the rare, unpredictable reaction described here.

An idiosyncratic reaction is an unusual, unpredictable drug response that occurs in a small subset of people and is not related to the dose or the drug’s normal pharmacology. These reactions are not anticipated from typical drug effects and often arise from genetic, metabolic, or immune factors that make certain individuals react differently. That fits the idea of an unexpected and uncommon effect after administration.

In contrast, a side effect is a predictable, often dose-related effect that accompanies therapy and is understood from the drug’s usual action. Tolerance refers to a diminished response with repeated dosing, requiring higher amounts for the same effect. Dependence involves physiological adaptation such that withdrawal occurs if the drug is stopped. These concepts describe more predictable or gradual processes, not the rare, unpredictable reaction described here.