Dr Thomas E Smith MBBS(Hons) MD FRCA FFPMRCA
Opioids like morphine have a proven role for treating short-term pain and cancer pain but there are concerns about their effectiveness for chronic non-cancer pain.
Studies looking at the use of opioids in chronic pain have found that only about 16% have improvement in function and a stable opioid dose at one year, with most patients reporting no improvement in pain despite increasing opioid doses. Long-term opioids may limit response to other treatments.
Conditions in which the central pain system is wound up – such as in fibromyalgia, chronic abdominal pain, and chronic headache may often be made worse by taking opioids.
Concerns about long term opioids
Opioid prescribing increased greatly worldwide from the 1990’s , with a quadrupling in the USA in the decade to 2010. Most of this increase was due to treatment of chronic non-cancer pain.
During this time admissions drug dependence programmes and opioid related deaths also quadrupled This led to a re-evaluation of opioids for chronic pain. A number of negative effects and associations of long-term opioid treatment have come to attention:
- Opioid induced hyperalgesia (wind up of central pain amplifier resulting in worse pain) and tolerance – likely explanations for poor long-term effectiveness of opioids. This process may begin immediately opioid exposure occurs
- Physical dependence (may develop with one to 3 months of use)
- Increased rates of falls and fractures – especially in the elderly
- Increased incidence of depression and suicide
- Suppression of sex hormones– decreased energy, strength, libido, increased depression
- Supression of the immune system
- Daily use of opioids can be a cause of chronic headache
- Decreased life expectancy (after controlling for other factors)
Many of the above negative effects appear to be dose related which has led to recent recommendations to restrict opioid dosage. Studies indicate that the risk of harm increases greatly at doses above 120mg morphine oral equivalent per day and that pain relief is not improved by exceeding this dose long-term.
Are all opioids the same?
Conversion rates of opioids are notoriously inexact but for the purposes of translating this advice, 100mg Morphine oral per day could be regarded as equivalent to:
50mg oxycodone orally
25mcg/hr Fentanyl patch
40mcg/hr Buprenorphine patch
Tramadol and Tapentadol are drugs that work in a combination of ways – only part of which is an opioid effect. These drugs used at their maximum recommended dosages are well under the 100mg-120mg morphine ceiling.
Sensible use of opioids:
With current knowledge we must all be careful when using opioids for chronic pain. We should try to minimize their use and the doses when used. People should only continue to take them if they are definitely helping them to live a more active life. Here are some principles that we all should follow:
- Look at lifestyle strategies to help quality of life – can physical activity and social life be helped with new approaches?
- Have non-drug treatments been tried – physiotherapy advice, pain management strategies, pilates, yoga, acupuncture, injections etc?
- Have non-opioid drugs have been tried?
- Be aware that opioids often provide short term relief that is not sustained – so a quick benefit does not mean they are the answer for long term pain relief.
- Be aware of short-term negative effects of opioids – sedation, nausea, constipation, dizziness, itching, dry mouth. Be aware of interaction with other brain affecting drugs such as alcohol and sleeping tablets.
- Be aware of the risks of long term high dose opioids – specifically: tolerance and hyperalgesia (worse pain), impaired thinking, depression, constipation, sexual dysfunction, falls/accidents/fractures, dependence and addiction.
- Patient and prescribers should agree a trial period with agreed goals – preferably lifestyle activity goals. Eg. one month trial – goal of increasing working hours and socializing.
- Avoid long-term use without clear benefit. If lifestyle and activity goals are not being not met then question the use of opioids and seek alternative strategies
If a decision is made to prescribe opioids for chronic pain:
- Keep the opioid dose as low as possible
- Avoid concurrent brain activity suppressors like benzodiazepines (clonazepam, diazepam, temazepam) and other sleeping tablets
- Prescriptions should be for one month maximum. The effect of the drugs on lifestyle and activity should be looked at – not just pain
- Consider risks versus benefits (see above) very carefully before increasing an opioid dose in chronic non-cancer pain.
Who should prescribe the opioids?
Patients and health staff should be clear on who is taking responsibility for prescribing the opioids and monitoring the opioid response.
There should be one prescriber – normally the patient’s GP.
Opioids Interfering with other treatments ?
Success rates of other pain treatments including injections and pain management programmes are lower in patients receiving high dose opioids.
For these reasons, patients may be asked to reduce their opioids before proceeding with other treatments.
Useful Reference:
For more information you may like to look at:
https://www.fpm.ac.uk/faculty-of-pain-medicine/opioids-aware
Opioids Aware: A resource for patients and healthcare professionals to support prescribing of opioid medicines for pain. A Public Health England funded project.