Prescribing drugs of dependence in general practice

Part C1 - Opioids

Patient selection for opioid therapy

Last revised: 22 Jun 2020

GPs should be aware that certain patient groups have increased risks of harm in association with opioid use. As part of a patient selection and risk stratification approach, the following patient group attributes should be considered.

Most drugs that are used for pain management cross the placenta. The Australian Drug Evaluation Committee (ADEC) classifies drugs according to fetal risk and notes that there are particular times of concern during pregnancy: weeks 4–10 (organogenesis), and just before delivery. Opioid analgesics taken just before delivery may cause respiratory depression in the newborn, and withdrawal effects may occur in neonates of dependent mothers.

It is always better to avoid drugs during pregnancy. If medication for constant pain relief is required during pregnancy, consultation should occur with a specialist obstetrician or pain physician.

In practice

Prescribers should avoid initiating opioid therapy in pregnant women whenever possible. It is accepted that prescription of ORT for pregnant women with opioid-related substance misuse is a harm minimisation strategy.
For pregnant women already on opioids, opioid therapy should be tapered to the lowest effective dose slowly enough to avoid withdrawal symptoms and then discontinued if possible.194 GPs should access appropriate expertise if considering tapering opioids because of possible risk to the woman and to the fetus if withdrawal occurs.15

During breastfeeding, occasional doses of opioids are considered safe, but codeine should be avoided. Use repeated doses with caution, especially if the infant is premature or under four weeks of age. The infant should be monitored for sedation and other adverse effects.77

Patients on workers’ compensation are at risk of being prescribed high-dose opioids, because of higher levels of psychological distress, poorer surgical outcomes and protracted involvement in legal proceedings.195

It is well recognised that patients who are psychologically distressed after a work injury have poorer outcomes.196,197 Therefore, as soon as distress is recognised (even at the first consultation), the patient should be referred to an appropriate health professional (commonly a psychologist) and therapeutic steps undertaken to minimise opioid use.

Evidence also shows that, where possible and appropriate, returning to work has substantial benefits in improving patient morbidity and decreasing mortality.198 When assessing the capacity of the patient to return to work, patient self-assessment of ability is usually reliable, if it matches clinician impression. Activity is not limited to work but includes the usual activities that the patient undertakes in sport, recreation and at home.

For low back pain, patients are most at risk of developing chronic pain syndrome in the period between 8–12 weeks following the date of pain onset.199,200 However, recovery rates are not improved by commencing a new activity program in the first 4–6 weeks after injury.201,202

In practice

Clinicians and patients should be aware of the risks involved with workers’ compensation patients, and focus rehabilitation on increasing function, non-pharmacological approaches and keeping opioid analgesia to a minimum.

Returning to as much usual activity as soon as possible is the most important treatment for musculoskeletal injuries. For cases of increased complexity multidisciplinary involvement is beneficial, (refer to Prescribing drugs of dependence in general practice, Part C2: The role of opioids in general practice – Section 3.2 Multidisciplinary approach) including teamwork with specialists and a physiotherapist (refer to Prescribing drugs of dependence in general practice, Part C2: The role of opioids in general practice – Section 4.2 Activity and exercise interventions) with pain management experience.

Opioids can interfere with complex tasks such as driving due to sedation; diminished reaction times, reflexes and coordination; reduced peripheral vision due to the persistent miotic effects;203 and decreased ability to concentrate.204

There is little direct evidence that opioid analgesics (eg hydromorphone, morphine or oxycodone) have direct adverse effects on driving behaviour.205 The risk of accidents appears to increase in the first weeks of starting opioid therapy or after increasing the dose.204,206,207 This may be dose dependent.14

There does not appear to be evidence that any one opioid has less impact than another.208 However, stable doses of sustained-release opioids do not appear to impair driving activity.204,206,209–211

According to Austroads, a person is not fit to hold an unconditional licence if they have an alcohol disorder or other SUD (eg substance dependence, heavy frequent alcohol or other substance use) that is likely to impair safe driving.205,212

The state or territory driver licensing authority may consider a conditional licence. This is subject to periodic review, taking into account the nature of the driving task and information provided by the treating doctor as to whether the following criteria are met:212

  • The person is involved in a treatment program and has been in remission for at least three months
  • There is an absence of cognitive impairments relevant to driving
  • There is absence of end-organ effects that impact on driving

In practice

Each patient should be considered individually and it is ultimately the prescriber’s judgement that determines opioid prescription.207,213–215 Where there are concerns about a patient’s ability to drive (eg high doses of opioids or opioids plus other sedative medication), a formal driving assessment may be considered.

When starting opioid therapy, patients should be advised that they are likely to be impaired and should not drive until a stable regime has been obtained for at least two weeks.

There is moderate, generally consistent evidence that driving performance of patients on long-term opioids for chronic pain may not be negatively affected by their medication.204,211 Driving at night may be a problem due to the persistent miotic effects of opioid drugs reducing peripheral vision.203
 

Sleep-disordered breathing describes a spectrum of disorders, including obstructive sleep apnoea (OSA). One in 15 adults has moderate or more severe OSA, experiencing partial or complete cessation of breathing many times during sleep, and around 80% of those who could benefit from treatment remain undiagnosed.216

Compared to people without OSA, people with OSA are at higher risk of increased sensitivity to opioid analgesia and decreased sensitivity to pain.217 Administration of opioids may also exacerbate OSA.218,219

Experts in this area recommend non-opioid analgesics, and other pain management techniques should be used as either an alternative to opioids or to help limit the amount of opioid required.220–222

In practice

If opioids are prescribed for patients with mild sleep-disordered breathing, careful monitoring and cautious dose titration should be used. Prescribing opioids to patients with moderate or severe sleep-disordered breathing should be avoided whenever possible to minimise risks for opioid overdose.15,223

The use of opioids in patients with severe untreated sleep apnoea is not recommended.54

As the population ages the challenge of safe and appropriate pain management increases. Management challenges include age-related changes in physiology, increased risk of falls,224,225 pharmacodynamics and pharmacokinetics, higher prevalence of comorbidities and concurrent medications, altered responses to pain, and difficulties with assessment of pain severity and response to treatment, including problems related to cognitive impairment.

Consider the use of non-drug strategies such as movement, exercise, physiotherapy and psychological therapies as alternatives to, or in combination with, medication.226 Where opioids are used, consider risk assessment for falls and interventions to mitigate common risks of opioid therapy such as constipation. Also, monitor older patients for the presence of cognitive impairment.15,226

Despite the higher incidence of side effects with drug therapy in older people, analgesics may still be safely and effectively used if tailored for the individual patient and comorbidity and other medications are considered.226 However, analgesics should be:226

  • initiated one at a time using a low dose
  • monitored regularly and adjusted as needed to improve efficacy and limit adverse events • titrated slowly according to response
  • used in combination where synergistic effects provide improved pain relief with fewer side effects than higher doses of a single drug.

When prescribing opioids to older adults, it is important to provide education about risky medication-related behaviours such as obtaining controlled medications from multiple prescribers and saving or stockpiling unused medications.15

Opioid therapy

Appropriate precautions must be taken when considering opioid therapy for older patients.227 These precautions include lower starting doses, slower titration, longer dosing intervals, more frequent monitoring and tapering of benzodiazepines.194,227 There is an increased risk of adverse effects including cognitive impairment, sedation, respiratory depression and falls.228,229 The risk of respiratory depression is minimised by monitoring the patient for sedation and reducing the dose of opioid if this occurs.228

While there are large individual differences, older patients are more sensitive to opioids and dose requirement decreases progressively with age, often reduced by 50% or more. There may be fewer pharmacokinetic differences between older and younger patients with fentanyl,81 morphine, oxycodone230 and buprenorphine.108 However, in the clinical setting, there is evidence of an age-related 2–4-fold decrease in morphine and fentanyl requirements.231,232 In patients older than 75 years, the elimination half-life of tramadol is slightly prolonged233 and lower daily doses have been suggested.234

In practice

Older patients require less opioid medication than younger patients to achieve the same degree of pain relief; harms can also occur at lower doses than they occur in younger patients.231,232,235 However, inter-patient variability exists in all age groups and doses must be titrated to effect in all patients.

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