Opiates and elderly
General Overview
- Pain is prevalent in older adults, especially in long-term care settings.
- Up to 80% of long-term care residents experience significant pain.
- Opiates are effective for nociceptive and neuropathic pain.
- Older adults are at higher risk of adverse effects due to pharmacokinetic and pharmacodynamic changes.
πΉ Pharmacological Considerations in the Elderly
Age-related changes affecting opioids:
- β GI motility and gastric acidity β altered absorption.
- β Fat, β lean mass and total body water β affects drug distribution.
- β Hepatic blood flow β reduced first-pass metabolism.
- β Renal clearance β accumulation of renally-excreted opioids (e.g., morphine, hydromorphone).
Dosing recommendations:
- Start at 25β50% of usual adult dose.
- “Start low and go slow”.
- Avoid: Meperidine, Propoxyphene, Tramadol (neurotoxicity, ineffectiveness, serotonin syndrome/seizures).
- Codeine: variable effect due to CYP2D6 metabolism (30% are poor metabolizers).
πΉ Commonly Used Opioids
- Step 2 WHO ladder: Oxycodone, hydrocodone + paracetamol/NSAID.
- Short-acting options: Morphine, oxycodone, codeine, hydromorphone.
- Avoid multiple opioidsβuse one agent and titrate.
- Titrate:
- Mild pain: β by 25β50%
- Moderate-severe pain: β by 50β100%
- Dose escalation intervals depend on formulation (e.g., 24h for SR opioids, 72h for fentanyl/methadone).
- Use PRN orders carefullyβdose ranges should be no more than 4x the minimum.
πΉ Side Effects of Opioids in the Elderly
Adverse Effect | Mechanism / Notes |
---|---|
Nausea | CTZ stimulation, vestibular activation. Most common (14%). |
Constipation | Mu-opioid receptor agonism β β GI motility. No tolerance develops β prophylactic laxatives essential. |
Urinary Retention | Anticholinergic effect and from constipation. |
Sedation/Cognitive Impairment | CNS depression; β risk with benzodiazepines/antidepressants; polypharmacy risk. |
Myoclonus | Accumulates with chronic therapy; more common with morphine (active metabolite). |
Pruritus | Seen in 2β10%, usually self-resolving. |
Respiratory Depression | Dose-dependent ΞΌ-receptor effect. Use naloxone if RR < 8 or SpOβ < 90%. |
Opioid-induced Hyperalgesia | β pain sensitivity due to toxic metabolites (M3G/H3G), NMDA activation. |
QT Prolongation | Associated with methadone, especially in HIV+ patients. |
Endocrine effects | β LH/testosterone/cortisol; β prolactin β β libido, bone density, sexual dysfunction. |
πΉ Management of Side Effects
- Dose reduction (25β50%) for adverse effects without compromising analgesia.
- Symptomatic treatment (e.g., antiemetics, laxatives).
- Opioid rotation for intolerable side effects.
- Change route (e.g., oral β transdermal) if needed.
- Add adjuvants (e.g., TCAs, gabapentinoids, steroids) if opioid dose is insufficient or poorly tolerated.
πΉ Additional Prescribing Principles
- Document response to PRNs to guide ongoing management.
- Equianalgesic conversions should factor in cross-tolerance:
- Reduce dose by 33β50% (except fentanyl/methadone).
- Methadone requires specialist knowledge due to nonlinear conversion.
- Long-acting opioids require careful initiation and titration; avoid frequent changes.
- Involve patient/family in education and decision-making.
πΉ Key Recommendations from AGS/WHO
- Prefer scheduled over βon demandβ dosing.
- Monitor closely for side effects and adjust accordingly.
- Assess pain routinely, even in patients with cognitive impairment.
- Premedicate known pain-triggering procedures in cognitively impaired patients.