Article Figures & Data
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Neuropathic Peripheral (complex regional pain syndrome, HIV sensory neuropathy, metabolic disorders, phantom limb pain, postherpetic neuralgia, diabetic neuropathy) Central (poststroke pain, multiple sclerosis, Parkinson disease, myelopathies, fibromyalgia) Musculoskeletal Myofascial pain syndrome Inflammatory Inflammatory arthropathies, infection, postoperative pain, tissue injury Mechanical or compressive Low back pain, neck pain, musculoskeletal pain, renal calculi, visceral pain from expanding tumor masses Pharmacologic concern Change with normal aging Common disease effects Gastrointestinal absorption or function Slowing of gastrointestinal transit time may prolong effects of continuous-release enteral drugs
Opioid-related bowel dysmotility may be worse in older patientsDisorders that alter gastric pH may reduce absorption of some drugs
Surgically altered anatomy may reduce absorption of some drugsTransdermal absorption Under most circumstances, there are few changes in absorption with age, and differences in absorption may relate more to different patch technology used Temperature and other specific patch technology characteristics may affect absorption Distribution Increased fat-to-lean body weight ratio may increase volume of distribution for fat-soluble drugs Aging and obesity may result in longer effective drug half-life Liver metabolism Oxidation is variable and may decrease, resulting in prolonged drug half-life
Conjugation is usually preserved
First-pass effect usually unchanged
Genetic enzyme polymorphisms may affect some cytochrome enzymesCirrhosis, hepatitis, and tumors may disrupt oxidation but not usually conjugation Renal excretion Glomerular filtration rate decreases with age in many patients, which results in decreased excretion Chronic kidney disease may predispose further to renal toxicity Active metabolites Reduced renal clearance will prolong effects of metabolites Renal disease
Increase in half-lifeAnticholinergic side effects Increased confusion, constipation, incontinence, movement disorders Enhanced by neurologic disease processes Reprinted from American Geriatrics Society Panel on Pharmacological Management of Persistent Pain in Older Persons. Pharmacological management of persistent pain in older persons. J Am Geriatr Soc 2009; 57:1331–1346.
Opioid Onset of action Recommended starting dose (opioid-naïve) Duration of analgesia (hours) Equianalgesic dose (mg) Parenteral Oral Morphine 10 30 Oral (immediate-release) 0.5–1 hours 2.5–10 mg every 4 hours 3–4 Oral (long-acting) 4–6 hours 15 mg every 8–24 hours 8–12 Intravenous (IV) 5–10 minutes 2.5–5 mg every 4 hours 3–4 Subcutaneous (SQ)a 20 minutes 5–10 mg every 4 hours 3–4 Intramuscular (IM)b 10–30 minutes 5–10 mg every 4 hours 3–4 (variable) Codeinec 1.5–2 hours 30 mg every 4 hours 4–6 100 200 Tramadold
(immediate release)1 hour 25 mg daily 4–6 (initially)
3–11 (chronic)100 120 Hydrocodonee 0.5–1 hour 2.5–5 mg every 4 hours 4–8 NA 30 Oxycodone NA 20 Immediate-releasef 1 hour 2.5–5 mg every 4 hours 3–6 Long-actingg 3–4 hours 10 mg every 12 hours 8–12 Hydromorphone 1.5 7.5 Oral 15–30 minutes 2–4 mg every 4 hours 3–6 Intravenous 5 minutes 0.3–1 every 4 hours 3–4 Fentanyl Not recommended for opioid-naïve patients 0.1 NA IV/SQ IV: immediate 25–50 µg every 1–2 hours IV: 0.5–1 SQ: 20 minutes SQ: 1–2
Increases with repeated useTransdermal patch 12–24 hours 12–25 µg every 72 hours 48–72 per patch
Up to 12 after removalMethadoneh Oral 0.5–1 hour 2.5 mg every 8–12 hours 3–4 (initially)
6–8 (chronic)
Increases with repeated use10 20 IV/SQ/IM 10–20 minutes 1.25 mg every 8 hours ↵a More appropriate in a continuous dosage.
↵b Not recommended due to painful administration.
↵c Not recommended due to adverse effects increasing disproportionately to analgesic effects.
↵d Maximum dose 300 mg daily if creatinine clearance > 30 mL/min or 200 mg daily if creatinine clearance < 30 mL/min.
↵e Only available in combination medications (paracetamol), which limits its dosage.
↵f Reduce dose and titrate more cautiously in patients with renal insufficiency (creatinine clearance < 60 mL/min).
↵g Some opioid-tolerant patients may require dosing every 8 hours for effective analgesia.
↵h Consult a pain management expert before initiating.
