TABLE 3

Most commonly used opioids

OpioidOnset of actionRecommended starting dose (opioid-naïve)Duration of analgesia (hours)Equianalgesic dose (mg)
ParenteralOral
Morphine1030
Oral (immediate-release)0.5–1 hours2.5–10 mg every 4 hours3–4
Oral (long-acting)4–6 hours15 mg every 8–24 hours8–12
Intravenous (IV)5–10 minutes2.5–5 mg every 4 hours3–4
Subcutaneous (SQ)a20 minutes5–10 mg every 4 hours3–4
Intramuscular (IM)b10–30 minutes5–10 mg every 4 hours3–4 (variable)
Codeinec1.5–2 hours30 mg every 4 hours4–6100200
Tramadold
(immediate release)		1 hour25 mg daily4–6 (initially)
3–11 (chronic)		100120
Hydrocodonee0.5–1 hour2.5–5 mg every 4 hours4–8NA30
OxycodoneNA20
Immediate-releasef1 hour2.5–5 mg every 4 hours3–6
Long-actingg3–4 hours10 mg every 12 hours8–12
Hydromorphone1.57.5
Oral15–30 minutes2–4 mg every 4 hours3–6
Intravenous5 minutes0.3–1 every 4 hours3–4
FentanylNot recommended for opioid-naïve patients0.1NA
IV/SQIV: immediate25–50 µg every 1–2 hoursIV: 0.5–1
SQ: 20 minutesSQ: 1–2
Increases with repeated use
Transdermal patch12–24 hours12–25 µg every 72 hours48–72 per patch
Up to 12 after removal
Methadoneh
Oral0.5–1 hour2.5 mg every 8–12 hours3–4 (initially)
6–8 (chronic)
Increases with repeated use		1020
IV/SQ/IM10–20 minutes1.25 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.