The review literature on the metabolism of many commonly used opioids and the known activities of its metabolites is reviewed in this article. The impact of renal failure on these medicines' and their metabolites' pharmacokinetics is then discussed. Finally, a review is given of how renal dialysis affects opioid medications and their metabolites. Based on the analysis, it is advised that methadone and fentanyl/sufentanil appear to be safe to use, whereas morphine and codeine should be avoided in patients who are on dialysis or have renal failure. Hydromorphone or oxycodone should also be taken with caution and strict monitoring. The "safe" medications for renal failure are also the least dialyzable, it is noted.
