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Letter to the Editor
I am writing in response to the article by Dr Philip Corke (Aust Prescr 2013;36:202-5) in which he discussed practical issues to consider when prescribing perioperative analgesia. This included planning for longer-term post-discharge pain management in a succinct yet informative manner.
I am disappointed, however, that he did not deal with the disturbing trend of routine prescribing of pregabalin and oxycodone with naloxone controlled-release tablets by acute pain services in certain tertiary hospitals.
Pregabalin is currently listed on the Pharmaceutical Benefits Scheme (PBS) under authority for 'refractory neuropathic pain not controlled by other drugs' and as adjunctive therapy in adults with partial seizures. Dr Corke appears to imply that pregabalin should be used in patients having procedures with a high risk of neuropathic pain, or patients who are predisposed to chronic pain. However, in my personal experience there are many patients who have been started on pregabalin as part of a routine oral analgesic combination after patient-controlled opioid analgesia is stopped. Subsequent management (and cessation) of pregabalin is usually left to the surgical team who do not know why pregabalin was originally prescribed. If the low-risk patient is discharged with pregabalin, then it will perpetuate the myth amongst primary care providers that this drug can be used for chronic pain that is not neuropathic in nature.
There is only one brand of oxycodone in combination with naloxone in Australia. It is PBS-listed for moderate–severe chronic pain unresponsive to non-opioid analgesia. This drug is not considered in recent guidelines.1 The main incentive to prescribe this drug is to avoid opioid-induced adverse effects, particularly constipation through naloxone as a competitive opioid antagonist at mu receptors in the gut wall. While the oxycodone component is believed to have bioequivalence with other single-drug sustained-release oxycodone, the naloxone component is reported to have less than 3% oral bioavailability due to significant first-pass metabolism, although naloxone, more than oxycodone, appears to be affected more in patients with renal or hepatic impairment.
NPS MedicineWise says that oxycodone with naloxone is 'not indicated for acute pain'.2However, the product information suggests otherwise as reproduced here:
Targin tablets are not recommended for immediate pre-operative use and postoperative use for the first 24 hours after surgery. Depending on the type and extent of surgery, the anaesthetic procedure selected, other co-medication and the individual health status of the patient, the exact timing for initiating treatment with Targin tablets depends on a careful risk-benefit assessment for each individual patient.
I have also noticed an increasing trend by several hospital-based acute pain services to prescribe oxycodone with naloxone after patient-controlled analgesia is stopped, even to patients with no history of constipation. Similar to pregabalin, this off-label use is a source of dilemma for surgical teams.
The first submission of oxycodone with naloxone to the Pharmaceutical Benefits Advisory Committee was rejected on the basis of an uncertain and high cost-effectiveness ratio. Subsequent approval was only granted after revised economic modelling comparative with long-term use of oxycodone plus an over-the-counter laxative.3 Therefore it is uncertain if decision making to prescribe oxycodone with naloxone for postoperative patients with low risk of constipation is based on similarly vigorous harm–benefit assessment.
Locum orthopaedic surgeon
- Macintyre PE, Scott DA, Schug SA, Walker SM. Acute pain management: scientific evidence. 3rd ed. Australian and New Zealand College of Anaesthetists and Faculty of Pain Medicine; 2010 .
- NPS RADAR: Oxycodone-with naloxone controlled-release tablets (Targin) for chronic severe pain. 2011 .
- Public Summary Document: Oxycodone hydrochloride with naloxone hydrochloride dehydrate. Pharmaceutical Benefits Advisory Committee. 2010 .
- Zhang J, Ho KY, Wang Y. Efficacy of pregabalin in acute postoperative pain: a meta-analysis. Br J Anaesth 2011;106:454-62.
- Engelman E, Cateloy F. Efficacy and safety of perioperative pregabalin for post-operative pain: a meta-analysis of randomized-controlled trials. Acta Anaesthesiol Scand 2011;55:927-43.
- Schmidt PC, Ruchelli G, Mackey SC, Carroll IR. Perioperative gabapentinoids: choice of agent, dose, timing and effects on chronic postsurgical pain. Anesthesiology 2013;119:1215-21.
- Steele N, Stevens J. Where oh where has your Endone script gone? The oxycodone epidemic. In: Riley R, editor. Australasian Anaesthesia 2013. Melbourne: Australian and New Zealand College of Anaesthetists; 2013. p. 193-7.