Thank you for your personalised report on oxycodone useage ("Oxycodone update", May 2012). I do recall your report of June 2011. I have not changed my prescribing habits in light of that report, or even your more recent update.
I feel there are two drivers to the increased use of oxycodone that you have not touched on in your report. One is the increased use of opiates for chronic non-malignant pain, particularly for those with chronic arthritis conditions. Many of these people are already taking, or intolerant of, anti-inflammatories and simple analgesics, and have been unable to access orthopaedic surgery in the public sector. These people get some measure of relief from opiate pain killers, with low risk of diversion or serious dependency.
The second feature which takes the prescription of oxycodone over morphine is PHARMAC's decision to choose a slow release morphine product which does not work. This left the field wide open for a medication that does work, and for the stated 12 hour duration. One can also argue that oxycodone has a fairly linear titration curve without any side effects, such as found with tramadol.
I trust this sheds some light on why oxycodone may be being initiated in general practice against your best wishes.
General Practitioner, Tauranga
Increased use of strong opioids for chronic non-malignant pain would certainly explain the overall increase in opioids dispensed in New Zealand over recent years. As oxycodone prescriptions are the main contributor to this increase, it is safe to assume that people with chronic non-malignant pain are being prescribed oxycodone. However, depending on the patient, the condition being treated and individual psychosocial factors, prescribing a strong opioid may not always be appropriate, and oxycodone should be reserved for people who are unable to tolerate morphine.
There is limited evidence to support the use of strong opioids for chronic non-malignant pain, however, in practice sometimes they will be required, when "all else fails". The reason that morphine is chosen first-line is that it is equally effective as oxycodone, has a similar adverse effect profile, is less expensive, and there is evidence that oxycodone may have a greater addictive potential. The article "Oxycodone – what can primary care do about the problem?" in BPJ 44 (May, 2012) discussed the role of strong opioids for chronic non-malignant pain and included guidance developed by the Australian and New Zealand college of Anaesthetists
There are currently two fully subsidised forms of long-acting morphine – Arrow Morphine LA and m-Eslon. We are unaware of any published data that shows these medicines to be ineffective for a 12 hour duration. We are interested in any other anecdotal reports of this lack of effect. If this is a widespread consensus, then it would indeed go some way to explain why oxycodone may be prescribed in preference to morphine.