Drug metabolism in malnutrition and obesity: clinical concerns.

In general, patients who are malnourished tend to have prolonged effects from drugs metabolized by the MFOS. On the other hand, in obese patients, drugs that undergo phase II metabolism tend to be metabolized more rapidly, thus shortening their duration of action. Therefore, clinicians must remember that, in protein-calorie malnutrition, drugs metabolized in the liver may be more likely to cause toxic effects due to the decreased rate of hepatic metabolism. Dose reduction could eliminate these adverse effects. Alternatively, drugs that undergo phase II metabolism may need to be administered at higher doses in obese patients, since the desired clinical effect may not be seen at a normal dose due to the obesity-related increase in hepatic metabolism. This should be considered before discontinuing the drug as a result of its lack of effect.