What is the recommended injection site for diclofenac (NSAID) administration?

Recommended Injection Site for Diclofenac Administration

Diclofenac injections should be administered intramuscularly in the deltoid muscle as the preferred site due to better bioavailability and less injection site pain compared to gluteal administration.

Rationale for Deltoid Injection Site

The selection of injection site for diclofenac administration is important for both efficacy and patient comfort. Current evidence supports the following considerations:

Advantages of Deltoid Administration

• The deltoid site allows for more reliable intramuscular deposition of medication, especially in patients with obesity or thick subcutaneous gluteal fat 1
• Significantly less pain at the injection site compared to gluteal injections 2
• Faster onset of analgesia with more patients achieving pain relief within 5 minutes when administered via deltoid 2
• Lower need for rescue medication (2.5% vs 9.82%) compared to gluteal administration 2
• Equivalent bioavailability to traditional gluteal injections, with comparable pharmacokinetic parameters 1

Clinical Applications

Diclofenac injections are commonly used in several clinical scenarios:

1. Acute Pain Management

   • First-line treatment for acute renal colic when diagnosis is clear 3, 4
   • Effective for postoperative pain management 2
   • Management of acute crystal-induced arthritis 3

2. Dosage Considerations

   • For acute renal colic: 75 mg intramuscularly 3, 4
   • For post-operative pain: 75 mg/1 ml formulation designed specifically for intradeltoid use 2

Implementation Considerations

When administering diclofenac injections:

• Use the 75 mg/1 ml formulation when available, which is specifically designed for intradeltoid administration 1, 2
• Standard 75 mg/3 ml formulations can be administered intragluteally but may not reach the muscle in obese patients 1
• Ensure proper technique to reach the deltoid muscle
• Monitor for adverse effects, although studies show good tolerability with minimal side effects 2

Contraindications and Precautions

• Use with caution in patients with:
  • Gastrointestinal bleeding risk
  • Severe renal impairment
  • Cardiovascular disease (lower doses preferred) 4

Alternative Routes

If intramuscular administration is not feasible:

• Oral NSAIDs can be effective but have slower onset of action 3
• Topical diclofenac is an option for localized pain, especially in hand osteoarthritis 3
• Rectal administration can be considered when vascular access is unavailable 4

The evidence clearly demonstrates that intradeltoid administration of diclofenac provides equivalent efficacy with better patient comfort and reliability of intramuscular deposition compared to traditional gluteal injections, making it the preferred site for diclofenac injections.