What is the recommended dose and administration of Diclofenac (Nonsteroidal Anti-Inflammatory Drug) intravenous for managing moderate to severe pain?

Recommended Dosage and Administration of Intravenous Diclofenac for Moderate to Severe Pain

The recommended dose of intravenous diclofenac for managing moderate to severe pain is 37.5 mg administered as an intravenous bolus injection every 6 hours, with a maximum daily dose of 150 mg. 1, 2

Dosing Guidelines

Initial Dosing

• For moderate pain (pain intensity rating 4-6):
  • Diclofenac 37.5 mg IV bolus
• For severe pain (pain intensity rating 7-10):
  • Diclofenac 37.5 mg IV bolus
  • Alternative: 75 mg IV bolus for very severe pain

Maintenance Dosing

• Repeat dose every 6 hours as needed
• Maximum daily dose: 150 mg (consistent with rheumatologic dosing guidelines) 3
• Duration: Short-term use only (typically 2-3 days for acute pain management)

Administration Technique

Modern formulations of diclofenac (HPβCD diclofenac/Dyloject®) can be administered as:

• IV bolus injection (preferred) - administered over 15-30 seconds 1, 4
• No need for dilution or slow infusion with newer formulations

Older formulations required:

• Slow IV infusion over 30-120 minutes due to solubility issues 4

Clinical Efficacy

Intravenous diclofenac has demonstrated significant efficacy in managing moderate to severe postoperative pain:

• Single-dose HPβCD diclofenac 37.5 mg provides similar analgesic efficacy to ketorolac 30 mg IV 1, 4
• Number needed to treat for 50% pain relief versus placebo:
  • 2.4 over 4 hours
  • 3.8 over 6 hours 2
• Median time to rescue medication: 226 minutes for diclofenac versus 80 minutes for placebo 2
• Significantly reduces opioid requirements in the postoperative setting 1

Special Populations and Considerations

Elderly Patients

• Consider starting with lower doses (18.75 mg IV) 1, 2
• Monitor closely for adverse effects, particularly renal function
• Use with caution due to increased risk of gastrointestinal and renal toxicity 3

Renal Impairment

• Use with caution
• Consider dose reduction or alternative analgesics

Monitoring and Safety

Adverse Effects to Monitor

• Gastrointestinal effects (most common)
• Renal function
• Cardiovascular status
• Injection site reactions (less common with newer formulations) 4

Common Pitfalls and Cautions

1. Avoid in patients with:

   • History of GI bleeding or ulceration
   • Severe heart failure
   • Severe renal impairment
   • Hypersensitivity to NSAIDs
   • Perioperative coronary artery bypass graft (CABG) surgery

2. Potential drug interactions:

   • Anticoagulants (increased bleeding risk)
   • ACE inhibitors and diuretics (reduced efficacy, increased nephrotoxicity) 3
   • Other NSAIDs (increased adverse effects)

3. Duration of therapy:

   • Limit to shortest duration possible to minimize adverse effects
   • Maximum recommended duration for acute pain: 5 days 5

Multimodal Approach

For optimal pain management, consider combining with:

• Acetaminophen/paracetamol (complementary mechanism)
• Opioids for breakthrough pain (diclofenac reduces opioid requirements) 1
• Local anesthetics when appropriate for procedure-related pain 3

Evidence Quality Assessment

The evidence supporting IV diclofenac use is generally of moderate quality:

• Multiple randomized controlled trials demonstrate efficacy 1, 4, 2
• Cochrane review notes limitations in available evidence, particularly for newer formulations 2
• Limited data in major cardiovascular surgeries and elderly populations 2

Intravenous diclofenac provides effective analgesia for moderate to severe pain with a favorable side effect profile compared to opioids, making it a valuable component of multimodal pain management strategies.