In patients with organ dysfunction, which pharmacokinetic processes can be affected?

In patients with organ dysfunction, which pharmacokinetic processes can be affected?

• A. Absorption only
• B. Distribution only
• C. Metabolism only
• D. Liver metabolism and kidney excretion

Answer: (D)

When organ function declines, the body’s ability to handle drugs is altered, especially for clearance. The liver metabolizes many drugs, and when hepatic function is impaired, enzyme activity and hepatic blood flow can decrease, slowing metabolism. This increases drug exposure and lengthens the drug’s half-life. The kidneys excrete many drugs and their metabolites; reduced kidney function lowers glomerular filtration and tubular clearance, leading to drug accumulation and prolonged effects. These two clearance pathways are the most consistently affected in organ dysfunction, making liver metabolism and kidney excretion the key processes that can be altered. Absorption and distribution can vary with illness, but the predictable, clinically important changes center on impaired hepatic metabolism and renal excretion.

When organ function declines, the body’s ability to handle drugs is altered, especially for clearance. The liver metabolizes many drugs, and when hepatic function is impaired, enzyme activity and hepatic blood flow can decrease, slowing metabolism. This increases drug exposure and lengthens the drug’s half-life. The kidneys excrete many drugs and their metabolites; reduced kidney function lowers glomerular filtration and tubular clearance, leading to drug accumulation and prolonged effects. These two clearance pathways are the most consistently affected in organ dysfunction, making liver metabolism and kidney excretion the key processes that can be altered. Absorption and distribution can vary with illness, but the predictable, clinically important changes center on impaired hepatic metabolism and renal excretion.