Duration of Action: Oxycodone vs Hydromorphone (Dilaudid)
No, oxycodone does not have a longer duration of action than Dilaudid (hydromorphone)—both immediate-release formulations have similar durations of approximately 4-6 hours, and extended-release formulations are comparable when dosed appropriately. 1
Immediate-Release Formulations
Both medications are dosed on similar schedules in clinical practice:
- Hydromorphone (Dilaudid): 2-4 mg orally every 4-6 hours as needed 1
- Oxycodone: 5-15 mg orally every 4-6 hours as needed 1
The dosing intervals are identical, reflecting equivalent durations of analgesic effect 1. Hydromorphone actually has a quicker onset of action compared to morphine, suggesting it may provide faster pain relief rather than longer duration 1.
Extended-Release Formulations
For extended-release versions, the evidence shows:
- Extended-release formulations of both drugs appear equal in terms of pain relief and side effect profile when dosed in an equianalgesic ratio (2:5 hydromorphone to oxycodone) 1
- Multiple studies comparing once-daily OROS hydromorphone with twice-daily sustained-release oxycodone demonstrated noninferiority, with both providing similar pain control over 24-52 weeks 2, 3, 4
- The median equianalgesic doses were 16 mg OROS hydromorphone once daily and 40 mg sustained-release oxycodone twice daily, maintaining the 2:5 ratio 2
Clinical Equivalence in Pain Management
Systematic reviews confirm that hydromorphone shows no evidence of superior effectiveness over oxycodone in patients with moderate to severe chronic pain, with mean pain scores being no different between the two medications 1. One analysis found pooled standardized mean difference of only 0.04 (P=5.8), which the authors questioned for clinical significance 1.
Pharmacokinetic Considerations
The key difference is not duration but rather:
- Hydromorphone is more potent (approximately 5-7 times more potent than morphine on a milligram basis), allowing for smaller doses 1
- Hydromorphone has a quicker onset of action compared to morphine 1
- Both drugs have similar half-lives when comparing immediate-release formulations 1
Important Clinical Caveats
In patients with renal dysfunction, hydromorphone may have reduced analgesic duration between doses due to accumulation of hydromorphone-3-glucuronide, which can cause increased sensory-type pain and reduced analgesia 5. This is a critical consideration when selecting between these agents in dialysis or renal impairment patients 5.
For acute severe pain in the emergency department, hydromorphone (0.015 mg/kg IV) is recommended as comparable and potentially superior to morphine, but this reflects onset and efficacy rather than duration 1.