Australasian Anaesthesia 2011 - Australian and New Zealand ...

Management of opioid side effects – a personal view 11Management of opioid side effects – a personal viewPAUL DE SOUZA, BSC(MED), MB BS, MPH, PHD, FRACPProfessor of Medical Oncology, University of Western Sydney School of Medicine, Conjoint Professor,University of NSW, Department of Medical Oncology, Liverpool Hospital, Liverpool, NSWProfessor Paul de Souza is a clinical academic medical oncologist at the University of Western Sydney, and isbased at Liverpool and Campbelltown Hospitals in Sydney. He has an interest in translational cancer research andclinical trials, and runs a laboratory focusing on cancer cell biology and drug development. Prior to his appointmentat UWS, he had a busy clinical practice at St George Public Hospital.INTRODUCTIONThere are many published reviews on the pharmacological management of pain 1,2,3,4 , particularly in relation to cancerpain, but very few on the side-effects of opioids. There are also recent reviews on the role of specific opioids in themanagement of pain 5,6 . This review will focus on the management of side effects from opioids in the cancer patient,from a personal perspective. It is hoped that this review will assist anaesthetists in developing an appropriatemanagement plan for management of opioid side effects in their patients in both acute and chronic settings. Chronicnon-cancer pain is becoming increasingly frequent, as is the use of narcotics for its management 7 , which will bringwith it challenges of its own, including issues such as psychological management of the patient and addiction, butthese will not be reviewed here. The perioperative management of chronic pain 8,9,10 , and the opioid – dependentpatient 11 are considered elsewhere.There is very little published research on management of side effects from opioids, and a dearth of therapeuticor comparative trials. Opioid-induced side effects are common, and well-known to practising doctors. Nausea,constipation, sedation, hallucinations and dry mouth are arguably more common than a group which includes itch,myoclonus, urine retention, and respiratory depression. 12 Management is largely based on personal experience,anecdote, consensus panels 13 and institutional guidelines.MANAGEMENT PRINCIPLESPrevention of opioid side effects, if possible, is perhaps the key to effective management. Since many side effectsof narcotics are well known and predictable, it makes sense to start pharmacological treatment at the same timeas opioids are prescribed, much in the same manner as potassium supplements are administered concurrentlywith the initiation of frusemide. Further, drugs should initially be administered regularly. Depending on the patient’sresponse to treatment and whether dose titration is necessary, pro re nata (PRN) orders may then be contemplated.Specific side effects should be treated promptly if there is a clear relationship to the opioid, but in the cancer patient,there may be multiple contributing factors to consider.Depending on the risk/benefit ratio, the onset of side effects, and whether pain is adequately controlled in agiven patient, reduction of opioid dose is often effective in helping to manage side effects. This can be a usefulstrategy in a patient who may also have co-analgesics introduced as part of their overall pain management plan.For instance, paracetamol added to oxycodone is often worthwhile, and doses of oxycodone may be reduced atthe same time paracetamol doses are increased, providing of course pain remains under control. Palliative carephysicians tend to use other complementary drugs for analgesia if the aim is not to increase narcotic dose in agiven patient. Antiepileptic medications such as gabapentin are frequently prescribed. Other adjunct treatments(antidepressants, steroids) are commonly used as a means of minimising opioid doses.Of course, the best management plan for pain involves treating the underlying cause. For patients with cancer,this may involve surgery (for example as a palliative treatment for bowel obstruction), radiation, chemotherapy oreven antibiotics if there is a suspicion of an infective cause.If, after some time, opioid dose reduction or administration of narcotic-sparing agents are not successful inreducing side effects, opioid rotation is sometimes used, though there does not appear to be good evidence tosupport this practice. 14 This clearly requires a longer term plan and frequent monitoring of the patient, and may bebest performed in an inpatient or hospice setting.Other issues such as polypharmacy can be a problem, especially in palliative care. However, in this setting,acute management of opioid side effects will probably remain largely pharmacological. If more chronic managementof opioid side effects is required, strategies such as dietary advice and exercise play an important part (and arehighly recommended for the management of constipation, for example).NAUSEAThis is usually a self-limiting symptom, lasting days to around a week, mostly due to initiation of narcotics or achange (increase) in dose. Exclusion of other causes for nausea would be prudent (consider liver metastases, brainmetastases, constipation, bowel obstruction).Prevention or treatment of nausea often involves regular administration of prochlorperazine, metoclopramide,haloperidol or steroids. Other more specialised agents such as cisapride are occasionally useful.Occasionally, patients complain of nausea when they are really referring to something else (eg. reflux, epigastricdiscomfort). A careful history is helpful. In my experience, nausea from opioids fluctuates in intensity and usuallyresponds to simple anti-emetics. Truly constant nausea is very unusual and is a potential sign of mislabelled nausea.Another consideration is the possibility of changing causes for nausea; nausea that improves with medication, thenrecrudesces several days later without an accompanying change in opioid or analgesic dosage is a clue that anothercause may be at play.