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Oxycodone Prescribing

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National pattern of prescribing for oxycodone and morphine

Note: The graph below shows morphine use is unchanged but oxycodone use has increased dramatically.

Question: Is this because oxycodone is being used inappropriately in the place of a weaker opioid?

Notes:
Data has been excluded where the NZMC number was not recorded.
Data excludes injectable forms of oxycodone hydrochloride and morphine.

Oxycodone prescribing needs review

Since the introduction of oxycodone to the New Zealand pharmaceutical schedule, the number of prescriptions for this strong opioid analgesic has steadily increased while the use of morphine has remained relatively constant.

There may be a perception amongst some prescribers that oxycodone is an alternative to a weak opioid such as codeine, but in fact oxycodone is strong opioid with similar indications and actions to morphine.

The data suggests that oxycodone is not being used instead of morphine, but rather instead of a weak opioid or other analgesic.

Would you give your patient morphine? If your answer is no, then oxycodone is not indicated.

Morphine, not oxycodone, is the usual first choice if a strong opioid is required. Oxycodone is only indicated as a second line alternative to morphine.

For a patient requiring relief for mild to moderate pain (step two on the WHO analgesic ladder) a weaker opioid is indicated, e.g. codeine, tramadol (opioid-like) or dihydrocodeine. Oxycodone should not be used in place of these medicines.

When is oxycodone indicated?

Oxycodone is indicated infrequently. If a strong opioid is indicated, morphine remains the preferred first-line analgesic. Oxycodone has no better analgesic efficacy than morphine but is significantly more expensive, see below. A switch from morphine to another strong opioid such as oxycodone would only be considered in the small proportion of patients who:

  • Develop neurotoxic adverse effects with morphine, such as confusion, hallucinations or myoclonic jerks
  • Experience other intolerable adverse effects such as excessive nausea
  • Develop a morphine-associated rash

Comparative costs of oxycodone and morphine for one month of treatment (twice daily dosing of long-acting preparations)

  Cost
Base dose Morphine Oxycodone (for equivalent dose)*
10 mg morphine
$11.88 $26.27
20 mg morphine $23.76 $39.00
30 mg morphine $18.90 $49.69
*Oxycodone is 1.5–2 times more potent than morphine. The equivalent dose of oxycodone has been calculated using an average conversion factor of 1.75.