Which statement correctly describes the mechanisms of ADRs?

Which statement correctly describes the mechanisms of ADRs?

• A. ADRs occur only due to immune responses
• B. On-target effects; off-target effects; toxic metabolite production; immune responses; idiosyncratic responses
• C. ADRs cannot be predicted
• D. All ADRs are dose-independent

Answer: (B)

Adverse drug reactions come from several mechanisms, not just one. They can occur when the drug hits its intended target but causes an unwanted effect (on-target effects), or when it interacts with other targets (off-target effects). Some ADRs arise from the formation of toxic or reactive metabolites that damage tissues. Immune-mediated responses, including hypersensitivity, are another mechanism, and some reactions are idiosyncratic, meaning they’re unpredictable and often linked to genetic factors. This broad view captures the full range of ways drugs can cause harm, which is why the statement listing all these mechanisms is the best description. It’s also important to note that many ADRs are dose-related rather than purely dose-independent, and not all ADRs are immune-mediated or unpredictable; some can be anticipated from the drug’s pharmacology and metabolism.

Adverse drug reactions come from several mechanisms, not just one. They can occur when the drug hits its intended target but causes an unwanted effect (on-target effects), or when it interacts with other targets (off-target effects). Some ADRs arise from the formation of toxic or reactive metabolites that damage tissues. Immune-mediated responses, including hypersensitivity, are another mechanism, and some reactions are idiosyncratic, meaning they’re unpredictable and often linked to genetic factors. This broad view captures the full range of ways drugs can cause harm, which is why the statement listing all these mechanisms is the best description. It’s also important to note that many ADRs are dose-related rather than purely dose-independent, and not all ADRs are immune-mediated or unpredictable; some can be anticipated from the drug’s pharmacology and metabolism.