Aspirin, dextropropoxyphene, non-steroidal anti-inflammatory drugs and pethidine, should not be used in
the presence of chronic renal failure
due to the risk of significant toxicity. In
the presence of hepatic impairment, most drugs are subject to significantly impaired clearance and increased oral bioavailability, but are poorly studied in the clinical setting. The agent least subject to alteration in this context is remifentanil; however the drugs' potency has other inherent dangers.