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,434,435 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.436 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.8,436
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.436 However, analgesics should be:436
- 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.8
Analgesics for older patients
In general, there is limited evidence about the use of analgesic medications in older patients. Older patients are often specifically excluded from clinical trials because of their age, comorbidities or concurrent medications.
For all patient groups, timing of medication administration and duration of action is important. Severe, episodic pain requires treatment with medicines with a rapid onset of action and short duration. However, if a patient is experiencing continuous pain, regular analgesia is the most effective, possibly using modified-release formulations.436
Paracetamol is recommended as a first-line therapy in older adults for mild to moderate pain. There is no evidence to support a need for dosage reduction of paracetamol in this group. Although there is emerging evidence of ineffectiveness of paracetamol in low back pain and some osteoarthritis conditions,295 these findings are disputed.
The use of non-selective NSAIDs is relatively contraindicated in older patients due to increased risk of gastric and renal side effects, as well as cardiovascular and cerebrovascular effects.437 However, individual circumstance and context may make these drugs an appropriate choice. A large 2010 study of patients with arthritis (mean age 80 years) found that overall, patients on NSAIDs appear to fare better than those taking opioids: the opioid cohort showed higher rates of fracture, hospital admission and all-cause mortality with similar or higher rates of cardiovascular, renal and gastrointestinal adverse effects.438
Judicious use is advised particularly in older patients;439 support with protective proton pump therapy is advised.440
Adjuvant therapies – Anticonvulsants
An increase in adverse effects with pregabalin appears to be dose related rather than associated with patient age. However, the initial doses of anticonvulsant drugs should be low and increases in dose should occur slowly. The reduction in renal function that occurs with increasing age means that the elimination of gabapentin and pregabalin may be reduced and lower doses required.
Monitoring of side effects is important, particularly for somnolence and dizziness with pregabalin, but the lack of hepatic metabolism and low drug interactions makes gabapentin and pregabalin useful in older patients.
Adjuvant therapies – Antidepressants
Caution should be exercised with TCAs as their clearance may decrease in older patients. Confusion and hypotension are more likely in this group due to increasing anticholinergic load. Lower initial doses are recommended with careful monitoring for side effects. Contraindications to TCAs include prostatic hypertrophy, narrow angle glaucoma, cardiovascular disease and impaired liver function.
Other antidepressants may be more appropriate: SNRIs (duloxetine) have shown to be effective and safe in older patients though care should be taken with poor renal function.
Appropriate precautions must be taken when considering opioid therapy for older patients.102 These precautions include lower starting doses, slower titration, longer dosing intervals, more frequent monitoring and tapering of benzodiazepines.78,102 There is an increased risk of adverse effects including cognitive impairment, sedation, respiratory depression and falls.441,442 The risk of respiratory depression is minimised by monitoring the patient for sedation and reducing the dose of opioid if this occurs.441
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 requirements.445,446 In patients older than 75 years, the elimination half-life of tramadol is slightly prolonged447 and lower daily doses have been suggested.448
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.445,446,449 However, inter-patient variability exists in all age groups and doses must be titrated to effect in all patients.