What is the commonly used analgesic for acute pancreatitis pain?

Pain Management in Acute Pancreatitis

For severe acute pancreatitis pain, morphine is the first-line opioid of choice, while hydromorphone is preferred over morphine in non-intubated patients. 1, 2

Stepwise Analgesic Approach Based on Pain Severity

The analgesic strategy should follow a severity-based algorithm:

Mild Pain

• Start with NSAIDs (such as diclofenac) with or without paracetamol (acetaminophen) as initial therapy. 1 However, recent high-quality evidence suggests opioids may be more effective than NSAIDs even in mild cases. 3, 4
• Avoid NSAIDs in patients with acute kidney injury. 5

Moderate Pain

• Use weak opioids such as codeine or tramadol in combination with non-opioid analgesics. 1, 2
• Tramadol is commonly used as rescue analgesia in clinical practice. 6

Severe Pain

• Morphine is the opioid of first choice for moderate to severe pain. 1, 2
• In non-intubated patients, hydromorphone is preferred over morphine or fentanyl. 2
• Buprenorphine (a kappa-opioid agonist) has demonstrated superior efficacy compared to NSAIDs, requiring significantly less rescue analgesia (130 μg vs 520 μg fentanyl; P < .001) and providing longer pain-free intervals (20 vs 4 hours; P < .001). 3
• Pentazocine (another kappa-opioid agonist) also showed better pain control than diclofenac, with lower rescue analgesic requirements (126 μg vs 225.5 μg fentanyl; P = 0.028). 4

Evidence Reconciliation: Opioids vs NSAIDs

Despite theoretical concerns about opioids worsening pancreatitis through sphincter of Oddi spasm, the highest quality recent evidence demonstrates opioids are more effective than NSAIDs for pain control. 3, 4 A 2021 meta-analysis confirmed that opioids significantly decreased the need for rescue analgesia compared to non-opioids (OR 0.25,95% CI 0.07 to 0.86, P = 0.03). 7 The sphincter of Oddi concerns mentioned in drug labels 8, 9 have not translated into clinically significant complications in randomized trials. 7, 10, 3, 4

Rescue Analgesia

• Fentanyl delivered through patient-controlled analgesia (PCA) pumps is the standard rescue analgesic in clinical trials. 3, 4
• In clinical practice surveys, meperidine (pethidine) remains the most commonly used rescue analgesic (54.8%), followed by tramadol and morphine (17.8% each). 6

Managing Opioid-Related Adverse Effects

• Laxatives must be routinely prescribed for both prevention and management of opioid-induced constipation. 1, 2
• Metoclopramide and antidopaminergic drugs are recommended for opioid-related nausea and vomiting. 1, 2
• Common adverse effects include sedation, lightheadedness, dizziness, nausea, vomiting, and diaphoresis, which are more prominent in ambulatory patients. 8

Special Populations and Considerations

Renal Impairment

• Use all opioids with caution at reduced doses and frequency in patients with renal impairment. 2, 8
• Fentanyl and buprenorphine (transdermal or IV) are the safest opioids for chronic kidney disease stages 4 or 5 (eGFR <30 ml/min). 2

Cardiovascular Concerns

• Morphine may cause severe hypotension in patients with depleted blood volume or shock, and can produce bradycardia. 8
• Fentanyl should be administered with caution to patients with bradyarrhythmias. 9

Biliary Pancreatitis

• While opioids may cause sphincter of Oddi spasm, this theoretical concern has not resulted in increased complications in clinical trials. 8, 9, 7, 10

Advanced Interventions for Refractory Pain

When medications provide inadequate relief or cause intolerable side effects, celiac plexus block should be considered. 11, 1, 2 This is particularly effective for visceral pain in pancreatic disease, with significant advantages over standard analgesic therapy for up to 6 months. 11

Critical Pitfalls to Avoid

• Do not withhold adequate opioid analgesia based on outdated concerns about sphincter of Oddi spasm—the evidence does not support clinically significant harm. 7, 10, 3, 4
• Ensure adequate fluid resuscitation alongside pain management, as this is fundamental to optimizing tissue perfusion. 5
• All patients with severe acute pancreatitis should be managed in a high dependency or intensive care unit with full monitoring. 1
• Avoid NSAIDs in patients with acute kidney injury. 5