Oxycodone
Class: analgesic – full opioid agonist
Indications: step 3 in the WHO analgesic ladder; moderate to severe pain
Contraindications/cautions: severe renal failure, respiratory disease
Adverse reactions: see morphine
Metabolism/clearance: metabolised by metabolising enzymes CYP2D6 mainly in the liver
Interactions:
- increased clinical effect/toxicity of oxycodone (due to increased blood concentrations) may occur with some CYP metabolising enzyme inhibitors (see above) e.g. bupropion, fluoxetine, paroxetine, quinine
- additive CNS effects with other CNS depressants e.g. benzodiazepines (e.g. lorazepam), phenothiazines (e.g. chlorpromazine), tricyclic antidepressants (e.g. amitriptyline), other opioids, alcohol
- additive respiratory depression with benzodiazepines (e.g. midazolam), other respiratory depressants
| Dosing: (and see notes) | ||
|---|---|---|
| oral: | immediate release | initially in opioid naïve 1 to 3 mg 4 to 6 hourly |
| slow release | initially 5 mg every 12 hours | |
| subcut: | oral: subcut | 2:1 |
| rectal: | not available | |
Syringe driver: see syringe driver compatibility chart
Renal impairment: effects of opioids may be increased & prolonged
- eGFR 10 to 30 mL/min/1.73m^2 initially give 75% of estimated dose and titrate cautiously with appropriate monitoring
- eGFR <10 mL/min/1.73m^2 give 50% of estimated dose; titrate cautiously & monitor
- Care required with slow release formulations – accumulation may occur
Hepatic impairment: manufacturer recommends reduce initial dose 30 to 50% of usual dose in mild impairment; avoid in moderate to severe impairment
Mechanism of action: binds to opioid receptors in the brain and spinal cord inhibiting the ascending pain pathways thus altering perception and response to pain
Onset: oral: 20 to 30 minutes
Duration: oral (immediate release): 4 to 6 hours slow release: 12 hours
Notes:
- may be useful in opioid rotation
- dose conversion from oral morphine to oral oxycodone is 2:1 i.e. 10 mg oral morphine = 5 mg oral oxycodone because oral availability of oxycodone is twice that of morphine
- the slow release tabs should not be crushed/chewed
- oral liquid 5 mg/5 mL is available
- in renally impaired patients, one of oxycodone’s active metabolite may accumulate (see dose recommendations above)
- the combination oxycodone+naloxone slow release tablets are designed to reduce opioid induced constipation