In which older adult population is toxicity with fat-soluble drugs most likely?

• A. Sedentary
• B. Obese
• C. Malnourished
• D. Physically active

Answer: (B)

Fat-soluble drugs behave like they’re “stored” in fat tissue. In older adults who are obese, there is a larger fat mass that serves as a big reservoir for these lipophilic medications. This increases the volume of distribution and slows the drug’s return to the bloodstream, so the drug stays in the body longer and can accumulate with repeated dosing. The result is a longer half-life and a higher chance of toxicity, especially when liver and kidney function are already diminished with age.

The other groups don’t have the same storage burden: malnourished individuals have less fat to store lipophilic drugs, and simply being physically active or sedentary doesn’t create the same large adipose reservoir that obesity does.