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WRITTEN BY

Dr Sebastiano Mercadante
Dr Sebastiano Mercadante is director, anaesthesia and intensive care unit, and pain relief and palliative care unit, La Maddalena Cancer Center, Palermo, Italy

Guide to opioid switching

In a follow-up to his recent article on the rationale for opioid switching, Dr Sebastiano Mercadante offers a practical guide to switching, covering asymmetric tolerance and the need to look beyond equianalgesia tables


Tables of equianalgesia may serve as a basis to calculate conversion ratios between opioids. However, in real life, opioid switching is not performed in conditions of equianalgesia, therefore a prudent decrease of the calculated dose is recommended to transfer the asymmetric tolerance that is expected to be higher in patients receiving high doses of the first opioid.

Conversion ratios for various opioids have been calculated on the basis of the existing evidence.1

Table 1: Conversion ratios

Conversion from
  Switching to
Ratio
  Oral morphine
  Oral oxycodone
  1.5:1
  Oral morphine
  Oral hydromorphone
  5:1
  Oral morphine
  Transdermal fentanyl
  100:1
  Oral morphine
  Transdermal buprenorphine
  75:1
  Oral morphine
  Oral methadone
  5–10:1*

*The variability of the morphine–methadone ratio is due to the unique pharmacokinetic and pharmacodynamic characteristics of methadone. 


In addition, it appears that the reasons for making the switch may also influence the conversion ratio. Ratios may be higher in patients experiencing adverse effects or those receiving rapidly escalating or high dosages. Often, this suggests that the patient may be in a state of hyperalgesia and the discontinuation of the offending drug may, per se, improve the pain condition.2

Opioid switching should not be a mere mathematical calculation, but should take into account holistic management of the patient, including the evaluation of pain, the adverse effect intensity, comorbidities, as well as concomitant drug use.2

  • Dr Sebastiano Mercadante is director, anaesthesia and intensive care unit, and pain relief and palliative care unit, La Maddalena Cancer Center, Palermo, Italy


Please always refer to local prescribing information.

References

  1. Mercadante S, Caraceni A. Palliative Medicine 2011;25(5):504–515.
  2. Mercadante S, Bruera E. Cancer Treatment Reviews 2006;32(4):304–315.
Date of preparation: January 2016; MINT/PAEU-15039

 

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