Maximum Daily Dose of Diclofenac
The maximum daily dose of diclofenac is 150 mg per day, regardless of route of administration (oral, intramuscular, or intravenous). 1, 2, 3
Dosing by Route of Administration
Oral Formulations
- Standard tablets (25-50 mg): Maximum 150 mg/day, typically administered as 50 mg three times daily or 75 mg twice daily 1, 2
- Extended-release tablets (100 mg): Maximum 150 mg/day, administered as 100 mg once or twice daily (not exceeding 200 mg total) 1
- The 200 mg/day upper limit for extended-release formulations in rheumatoid arthritis is an exception, but 150 mg/day remains the standard maximum for most indications 4, 5
Injectable Formulations (IM/IV)
- Maximum dose: 150 mg/day, administered as 75 mg every 12 hours 1, 2, 3
- Minimum interval between doses: 12 hours to minimize adverse effects 2
- Intramuscular route is preferred over intravenous administration in most clinical settings due to lower risk of dilution and dosing errors 2
- IV administration should be reserved for severe cases or hospital settings with appropriate monitoring 2
Critical Safety Considerations
Why 150 mg/day is the Ceiling
- Exceeding 150 mg/day significantly increases gastrointestinal and renal toxicity without additional therapeutic benefit 2, 3
- Higher doses are associated with increased risk of peptic ulcer disease, GI bleeding, and renal impairment 1, 2
High-Risk Populations Requiring Caution
- Absolute contraindications: Active peptic ulcer disease, severe heart failure, liver failure, or history of GI bleeding 2, 3
- Relative contraindications requiring extreme caution: Age >60 years, history of peptic ulcer disease, concomitant anticoagulant use (increases bleeding risk 3-6 fold), pre-existing cardiovascular disease, or renal impairment 2, 6
Monitoring Requirements for Chronic Use
- Baseline and every 3 months: Blood pressure, BUN, creatinine, liver function tests, CBC, and fecal occult blood 2
- Discontinue if: BUN or creatinine doubles, liver function tests increase to 3× upper limit of normal, or signs of GI bleeding occur 2
- Dose reduction: Consider in patients with creatinine clearance <10 mL/min 2, 3
Common Pitfalls to Avoid
- Do not combine diclofenac with other NSAIDs or aspirin as this increases GI toxicity without improving efficacy 7
- Do not use with anticoagulants without close monitoring as INR can increase up to 15% and bleeding risk triples 2
- Avoid in pregnancy at ≥30 weeks gestation due to risk of premature closure of fetal ductus arteriosus 7
- Do not exceed 5 days of treatment for acute pain or 3 days for fever in OTC settings 8
Drug Interactions Requiring Dose Adjustment
- Methotrexate: Increases risk of methotrexate toxicity; monitor closely 7
- Pemetrexed: Avoid diclofenac for 2 days before, day of, and 2 days after pemetrexed administration 7
- CYP2C9 inhibitors (e.g., voriconazole): May require dose reduction due to enhanced diclofenac exposure 7
- Cyclosporine: Monitor for worsening renal function 7