ENCUENTROS PARA ESCUELAS PRIMARIAS Y ESPECIALES

16.1 OVERVIEW

Pain is subjective and person defined; it is always unpleasant.

It can be acute, which is a protective warning, predictable and responding well to treatment OR chronic, tending to be continuous, of moderate to high severity for more than six months and in contrast unpredictable.

Pain can be affected by fears, age, gender, culture, previous experience of either self or significant others. A history of substance use including alcohol, is commonly linked with chronic anxiety and chronic depression, which may negatively affect a patients

experience of pain.

Chronic pain affects between 10 – 15% of the general population rising to between 30 and 50% of substance misusers.

Pain in people who use drugs is common, complex and often forgotten and poorly treated. Up to 25% of people who use opioids say they start opiates because of pain.

Under-treatment is common and is often based on misconceptions.

There are a number of reasons why individuals who are drug dependent may have greater than expected needs regarding pain relief:

 Compared to those who are not dependent, the presence of a drug misuse syndrome seems to worsen the experience of pain – hyperalgesia.

 Drug misusers have a low tolerance of non-pharmacological interventions to achieve pain control.

 By nature of their condition, drug misusers have frequent episodes of intoxication, and withdrawal, which may alter the intensity of the pain experience.

 Virtually all forms of addiction are associated with sleep disturbance and this is a well established exacerbating factor in chronic pain.

 Depression and anxiety are common features in addiction and these have an important influence on the pain experience.

 Drug misusers are more likely to suffer from accidental and non accidental injury, and medical complications related to their drug use. This places them at high risk from physical problems that may require analgesia.

When a known substance misuser presents with a need for analgesia

 A full substance misuse and medication history should be taken. This can be used to check for drug interactions and to assist with choice and appropriate analgesic.

 The accurate assessment of contemporaneous treatment for addiction is also mandatory as many of these treatments have important implications for the use of opioid medications.

 It is important to discuss the patients use of alcohol as this has specific relevance to the experience of and management of pain.

 Pain symptoms must be properly evaluated including relevant investigations and taking note of potential contributors to the patients experience of pain.

 If non pharmacological interventions are known to have utility for the pain

condition described they should be offered to the patient, with a clear explanation of why such interventions are likely to help. Similarly non opioid medications should be used where supported by evidence, again with clear discussion of the rationale for any drug used.

 There is little published guidance for management of patients who have chronic pain requiring opioid therapy, and who currently exhibit aberrant behaviour which may indicate misuse or addiction, or have a history of substance misuse.

Nevertheless, some general principles may be applied:

 The therapeutic regimen should be selected with the risk of aberrant drug related behaviours in mind i.e. short acting opioids are widely acknowledged to have greater abuse potential than long acting or sustained release preparations.

 The prescriber must communicate clearly with the patient about setting

reasonable expectations or goals for therapy and bout the necessity to frequently assess the progress towards these goals. This must include a regular review of the prescription.

 The process of building trust between the clinician and the patient should include a candid discussion of acceptable and unacceptable behaviour. The results of such a discussion should be written down and given to the patient. This may take the form of a treatment contract although this is not required by law.

 Be aware of the various potential presentations and drug seeking behaviour.

Refer patient to, or seek advice from, a pain specialist or substance misuse specialist at an early stage where appropriate.

 Treatment decisions need to made in compliance with pertaining laws and regulations.

 Response to treatment including degree of pain control and progress towards agreed goals needs to be assessed frequently.

16.2 METHADONE AND P AIN

 Give the usual methadone maintenance dose to address the persons baseline opioid requirements.

 If an opioid analgesic is appropriate for the patients condition, a non-methadone opioid may be co prescribed in addition to the patients usual methadone dose.

 It is not necessary to “rationalise” the patients entire opioid requirements to one drug.

 Relatively high doses of opioids at short interval may be needed because of tolerance.

 Morphine is the preferred opioid agonist.

 It is usually necessary to give a dose that is at least the dose that would be given to a person not on substitute drug maintenance treatment. It is not possible to

Patients already tolerant to a long term illicit or prescription opiates taken for addiction will derive little analgesic effect from their regular dose. If the patient needs opiate analgesia these drugs will have to be prescribed in addition to any existing prescribed regimen.

predict how much extra dose will be required. Increased sensitivity to pain or cross tolerance will often necessitate higher or more frequent doses.

 Avoid partial agonist / antagonist drugs should for patients receiving methadone as withdrawal may be precipitated.

16.3 BUPRENOPRHINE (SUBUTEX / SUBOXONE) AND PAIN

Patients taking high dose Buprenorphine as substitution therapy may be relatively refractory to opioid prescribed for analgesia.

See specialist advice. Management could follow any of the following options.

 Try NSAIDs and paracetamol

 If the pain will be of short duration, continue buprenorphine maintenance therapy and titrate a short acting opioid agonist. Because higher doses of full opioid

agonist analgesics may be required in a person taking buprenorphine, be cautious if the person’s buprenorphine therapy is abruptly discontinued, as sedation and respiratory depression may occur.

 Alternatively, divide the daily dose of buprenorphine and administer every 6-8 hours (although this not a licensed use of subutex) However if opioid tolerance has developed, additional opioid analgesia may be required.

 Discontinue buprenorphine and treat with an opioid analgesic by titrating the dose to avoid withdrawal and then to achieve analgesia. Both sustained release and immediate release morphine may be used. Convert back to buprenorphine using the initiation and stabilisation protocol.

 If the person is in hospital, buprenorphine can be stopped and methadone maintenance and opioid analgesic used, but close observation is essential and naloxone should be immediately available. The person may be changed back to buprenorphine before discharge.

Advice should be sought from the Acute Pain Team on bleep 1449 (at DRI) or 3107 (at BDGH) or the on-call anaesthetist outside office hours.

16.4 NALTREXONE AND PAIN

Naltrexone is an opiate antagonist with no agonist properties and will totally block the effects of substantial doses of opioid analgesics. People taking Naltrexone should be aware of the potential problems and the need to alert clinicians.

 Discontinuation of naltrexone produces very few signs and symptoms, but long term use increases the concentration of opioid receptors in the brain and

produces a temporary exaggeration of response to the subsequent administration of opioid analgesics.

 If unexpected or severe pain should occur, then intravenous paracetamol, high dose nonsteroidal anti inflammatory drugs, and local anaesthetics are effective.

Ketamine is an effective analgesic and may be useful. There is no information available about whether Tramadol would be useful.

 Minor or intermediate elective surgery: discuss with the person and their

community drug team the possibility of management of the pain with none opioid

analgesics versus the risk of relapse if naltrexone is withdrawn and opioid

analgesics used. Naltrexone should be withdrawn 48-72 hours before the surgery is due to take place.

 Major surgery, with expected severe post operative pain: naltrexone should be discontinued 72 hours beforehand. Expect a degree of resistance to opioid analgesics, although there may be increased sensitivity.

16.5 PERI OPERATIVE PAIN

Methadone may be given as per the patient’s usual requirements within 2 hours before surgery, as per clear fluids policy. (PAT/T 24)

The anaesthetist will need informing of the amount and time of the last methadone dose given.

It may be necessary to omit or delay Buprenorphine dosing to prevent either opioid blockade or precipitated withdrawal effects.