OzEMedicine - Wiki for Australian Emergency Medicine Doctors

opiate Rx for pain relief may require modification in opiate-dependent patients but there is no cross-tolerance between opioids and most other drugs of abuse (eg. alcohol, benzodiazepines, cannabis, cocaine, amphetamines and thus altered morphine doses are not required in these non-opiate-dependent patients.
remain open and non-judgemental, promote realistic expectations and set clear limits
diagnose pain as for other patients
exclude serious pathology such as epidural abscess or vertebral osteomyelitis / discitis presenting as back pain
identify addictive disorder where possible, maintain high index of suspicion, consider drug use screening
look for signs of drug use (intoxication, withdrawal, track marks, etc)
if drug use identified, take thorough drug history - drugs used, Rx providers, comorbidities (eg. hep), psychiatric disorders
assess degree of distress and contribution of psychosocial factors
additional information from family & friends, usual prescriber or dispenser (to confirm current drugs/doses), regulatory authorities such as Medicare Prescription Shopping Program

consult and collaborate with registered methadone or buprenorphine prescriber or dispenser, drug and alcohol service, pain specialist or psychiatrist
communicate with patent's usual GP or drug and alcohol service
consider early referral for interdisciplinary assessment & Mx
Rx the painful condition (eg. splint fractures, drain abscesses, etc)
use best practice guidelines where available, empasising non-opiate Rx (eg. chlorpromazine for migraine)
maximise non-opiate analgesia
use non-drug Rx (see above)
consider tramadol, opiates and opioids, other adjuvants such as ketamine, clonidine (Catapres), anxiolytics, antidepressants, and anticonvulsants
patients booked for elective surgery should have pre-op assessment at least 1wk before surgery to plan pain Mx
- continue methadone up to surgery & post-op, replace parenterally if needed
- planned naltrexone cessation may be required
- no current consensus on whether buprenorphine should be ceased pre-op

taking methadone invariably results in opioid tolerance and lower pain thresholds
ensure usual dose of methadone is continued or replaced parenterally to prevent withdrawal
contact registered methadone prescriber or dispenser to check correct dose
in general, opioid-tolerant patients with post-op. pain require 2-3x more opioid than opiate-naive patients
- thus commence with dose 50-100% greater than usual

buprenorphine is a long acting (up to 72h) partial agonist of mu-opioid receptors which will oppose analgesic effect of opiates
- thus maximise use of non-opiate analgesia, consider tramadol, local anaesthetic blocks & non-drug Rx

naltrexone is a long acting (24-72h from oral dose, 3-6mths from implant) opioid receptor antagonist
receptor antagonism can be overcome by high doses of opioids in a monitored environment
cessation of naltrexone may cause increased opioid sensitivity and exaggerated response resulting in fatal resp. depression
- in this scenario, use low dose opiates with extreme care, closely monitoring effect and titrating dose.