Which could account for drug toxicity following a normally prescribed dose?

Which could account for drug toxicity following a normally prescribed dose?

• A. All of these
• B. Decreased renal clearance by the kidney
• C. Altered serum protein binding
• D. Liver impairment

Answer: (A)

When a standard dose causes toxicity, it often means the body's handling of the drug has changed, not that the dose was inherently wrong. Decreased renal clearance means the drug is cleared more slowly, so it stays in the body longer and reaches higher concentrations, increasing the risk of adverse effects. Liver impairment can reduce metabolism and elimination, leading to greater systemic exposure or altered formation of active metabolites, which can heighten toxicity. Altered serum protein binding changes how much drug is freely circulating; if more drug is unbound, more can interact with receptors and cause toxic effects even if the total drug level seems acceptable. Because any of these factors can raise active drug exposure from a normal dose, all of these scenarios could account for toxicity.

When a standard dose causes toxicity, it often means the body's handling of the drug has changed, not that the dose was inherently wrong. Decreased renal clearance means the drug is cleared more slowly, so it stays in the body longer and reaches higher concentrations, increasing the risk of adverse effects. Liver impairment can reduce metabolism and elimination, leading to greater systemic exposure or altered formation of active metabolites, which can heighten toxicity. Altered serum protein binding changes how much drug is freely circulating; if more drug is unbound, more can interact with receptors and cause toxic effects even if the total drug level seems acceptable. Because any of these factors can raise active drug exposure from a normal dose, all of these scenarios could account for toxicity.