Diclofenac Injection Dilution Recommendations
For intravenous administration, diclofenac should be diluted to 5 mg/mL in normal saline to minimize venous thrombosis, while intramuscular formulations can be given undiluted at 75 mg per dose.
Intravenous Administration
Dilution Protocol
- Dilute the intramuscular preparation (25 mg/mL) to 5 mg/mL in normal saline before IV administration 1
- Administer over 10 minutes minimum via a peripheral vein 1
- The undiluted 25 mg/mL formulation causes unacceptably high rates of venous thrombosis (85% in hand veins, 58% in antecubital veins) 1
- Dilution to 5 mg/mL dramatically reduces thrombosis rates to 38% in hand veins and only 8% in antecubital veins 1
Standard Dosing
- Maximum daily dose: 150 mg, administered as 75 mg every 12 hours 2
- Single dose: 75 mg diluted appropriately and given IV over 10-30 minutes 2, 1
- Minimum interval between doses: 12 hours 2
Novel Low-Volume Formulation
- HPβCD diclofenac formulation allows small volume bolus administration at lower doses 3
- Effective doses: 18.75 mg or 37.5 mg IV bolus every 6 hours for postoperative pain 3
- Can be given as rapid bolus without extended infusion time 3
- This formulation is solubilized differently and does not require the same dilution as standard preparations 3
Intramuscular Administration
Standard Protocol
- Administer 75 mg undiluted (75 mg/3 mL or 75 mg/1 mL formulations) 4
- Inject into gluteal region or deltoid (with 1 mL formulation) 4
- Maximum daily dose: 150 mg (75 mg every 12 hours) 2
Formulation Considerations
- Traditional formulation: 75 mg in 3 mL 4
- Newer concentrated formulation: 75 mg in 1 mL, allowing deltoid administration 4
- Both formulations show comparable bioavailability 4
Pediatric Dosing (Intravenous)
For children requiring IV NSAIDs, use alternative agents with established pediatric dilution protocols 5:
- Ketorolac: 0.5-1 mg/kg (max 30 mg) diluted appropriately 5
- Ketoprofen: 1 mg/kg every 8 hours 5
- Ibuprofen: 10 mg/kg every 8 hours 5
Diclofenac is not the preferred IV NSAID in pediatric populations based on available guideline evidence 5.
Critical Safety Considerations
Venous Complications
- Always use antecubital fossa veins rather than hand veins when possible - this reduces thrombosis risk from 38% to 8% even with diluted drug 1
- Avoid undiluted IV administration entirely due to 72-hour thrombosis rates exceeding 50% 1
Cardiovascular and Renal Risks
- Exercise caution in patients with pre-existing cardiovascular disease 2
- Monitor renal function, especially at higher doses (>100 mg/day) 2
- Risk of adverse effects increases with doses approaching 150 mg/day 2
Gastrointestinal Precautions
- Increased bleeding risk when combined with anticoagulants 2
- Higher risk in patients >60 years or with peptic ulcer history 2
Drug Interactions
- Significant interactions with aspirin, lithium, digoxin, methotrexate, and cyclosporin 6
- Avoid concurrent aspirin as it reduces diclofenac efficacy 6
Common Pitfalls to Avoid
- Never administer undiluted diclofenac IV - this is the most common error leading to venous complications 1
- Do not exceed 150 mg total daily dose by any route 2
- Avoid dosing intervals shorter than 12 hours for standard 75 mg doses 2
- Do not use hand veins for IV administration when antecubital access is available 1
- Remember that diclofenac has a short plasma half-life (1.5 hours) but persists in synovial fluid, so frequent dosing beyond recommended intervals provides no additional benefit 7, 6