MorphineThe main metabolites of morphine – morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) – cross the blood-brain barrier, causing central neurological effects. Both accumulate in renal failure. The half life of M6G, for instance, is normally just over 2 hours. In the presence of renal failure this can increase up to 10 fold.
Codeine and diamorphineThese drugs are metabolised to morphine and eliminated accordingly. For codeine, the active metabolite codeine-6-glucuronide is also excreted renally.
OxycodoneAs with morphine, oxycodone and its metabolites accumulate in renal failure. Although oxymorphone is the only clinically significant metabolite in humans, it is considerably more potent than the parent drug and toxicity can occur. Nevertheless, oxycodone is the opioid of choice in many renal units in the presence of mild to moderate renal failure. In these circumstances it is used cautiously and initiated at lower doses.
HydromorphoneHydromorphone-3-glucuronide (H3G), the main metabolite of hydromorphone, accumulates up to 4 times its normal plasma level. Accumulation of H3G causes neuro-excitation and cognitive impairment.
Fentanyl and alfentanilThese drugs are excreted by the kidneys but as their metabolites are inactive and non-toxic in humans they are considered safe in renal failure.
MethadoneMethadone is excreted into the GI tract not the kidneys, so is safe in renal failure. Drug elimination, however, is reduced by if the patient is constipated.
Opioid analgesics: Treating Pain in People with Cancer
Our purpose is to transform access to education.
We offer a diverse selection of courses from leading universities and cultural institutions from around the world. These are delivered one step at a time, and are accessible on mobile, tablet and desktop, so you can fit learning around your life.
We believe learning should be an enjoyable, social experience, so our courses offer the opportunity to discuss what you’re learning with others as you go, helping you make fresh discoveries and form new ideas.
You can unlock new opportunities with unlimited access to hundreds of online short courses for a year by subscribing to our Unlimited package. Build your knowledge with top universities and organisations.