Opioid metabolism and clinical aspects.

Opioids are are commonly used for the management of acute and chronic pain. Opioids have different physicochemical and pharmacokinetic characteristics, which explain the profound changes in the clinical effect in several clinical conditions. Pharmacokinetics influences the opioid response affecting bioavailability, production of metabolites with residual clinical activity, and elimination. Generality of opioid metabolism and clinical implications for specific opioids in different clinical conditions were reviewed to bridge the gap between pharmacokinetics and clinical response. The knowledge of opioid metabolism is essential, particularly for older and complicated patients who receive multiple medications and may have impaired of renal and hepatic function. The recognition of possible metabolic problems and the consideration of adverse drug-drug interactions are fundamental to optimize the use of opioids in clinical practice.