What is the recommended dosage and usage of Diclofenac (Nonsteroidal Anti-Inflammatory Drug) for various conditions?

Diclofenac Dosage and Usage Recommendations

For most conditions requiring diclofenac, start with oral formulations at 50 mg three times daily for acute pain or 100-150 mg/day in divided doses for osteoarthritis, reserving injectable forms (75 mg IM) for situations requiring rapid analgesia when oral administration is not feasible. 1

Oral Diclofenac Dosing by Indication

Acute Pain and Primary Dysmenorrhea

• Standard dose: 50 mg three times daily 1
• For more severe pain, an initial dose of 100 mg followed by 50 mg doses may provide superior relief 1
• Maximum daily dose: 150 mg 2

Osteoarthritis

• Recommended range: 100-150 mg/day in divided doses 1, 3
• Typical regimen: 50 mg twice or three times daily 1
• Start with paracetamol up to 4 g daily as first-line therapy; escalate to ibuprofen 1.2 g daily if inadequate response, then consider diclofenac if still insufficient 4

Rheumatoid Arthritis

• Recommended range: 150-200 mg/day in divided doses 1, 3
• Typical regimen: 50 mg three or four times daily 1

Ankylosing Spondylitis

• Recommended range: 100-150 mg/day 3
• Continuous NSAID therapy is conditionally recommended over on-demand use for active disease, primarily for symptom control 4
• Evidence for disease-modifying effects (preventing spinal fusion) is inconsistent with diclofenac 4

Injectable Diclofenac Dosing

Intramuscular Administration (Preferred Route)

• Standard dose: 75 mg IM per injection 5
• Minimum interval between doses: 12 hours 5
• Maximum daily dose: 150 mg (two 75 mg doses) 5, 2
• IM route is preferred over IV for most clinical settings due to rapid analgesia without technical complexity and reduced risk of dilution/dosing errors 5

Specific Clinical Applications

• Acute renal colic: 75 mg IM as first-line treatment when diagnosis is clear 5
• Acute crystal-induced arthritis: 150 mg daily for first 3 days, then 75 mg daily for 3 additional days 5
• Postoperative pain: 75 mg IM reduces opioid requirements 5

Intravenous Administration (Reserved for Specific Situations)

• Use only in severe cases not responding to IM or in hospital settings with appropriate monitoring 5
• Postoperative dosing: 18.75-37.5 mg boluses every 6 hours 5
• IV carries significant risks of dilution and dosing errors; many serious adverse effects attributed to large IV overdoses 5

Critical Safety Considerations

Absolute Contraindications

Avoid diclofenac completely in: 5, 2

• Active peptic ulcer disease
• Severe heart failure
• Liver failure
• History of GI bleeding

High-Risk Situations Requiring Extreme Caution

• Age >60 years 4, 5
• History of peptic ulcer disease 4, 5
• Concomitant anticoagulant use (increases bleeding risk 3-6 fold) 5, 2
• Pre-existing cardiovascular disease 4, 5
• Renal impairment 5

Dose-Dependent Toxicity

• Higher doses (>150 mg/day) significantly increase GI and renal toxicity without additional benefit 4, 5, 2
• Diclofenac shows dose-dependent GI bleeding risk: OR 2.2 for 75 mg/day, 3.2 for 75-150 mg/day, and 12.2 for >150 mg/day 4
• Diclofenac carries intermediate GI risk compared to ibuprofen (lowest risk) and azapropazone (highest risk) 4

Gastroprotection Strategy

For patients with increased GI risk, use either: 4

• Non-selective NSAIDs plus proton pump inhibitor (PPI), OR
• Non-selective NSAIDs plus misoprostol, OR
• Selective COX-2 inhibitor

Standard-dose H2 blockers are less effective than PPIs or misoprostol 4

Monitoring Requirements for Chronic Use

Monitor at baseline and every 3 months: 5, 2

• Blood pressure
• BUN and creatinine
• Liver function studies
• Complete blood count
• Fecal occult blood

Dose Adjustments for Organ Dysfunction

• Renal impairment (CrCl <10 mL/min): Consider dose reduction; discontinue if BUN or creatinine doubles 5
• Hepatic dysfunction: Use with caution; discontinue if liver enzymes increase to 3× upper limit of normal 5

Treatment Duration and Failure

• Use lowest effective dose for shortest duration consistent with treatment goals 1
• If two NSAIDs tried in succession without efficacy, switch to alternative analgesia (opioids or non-pharmacologic interventions) rather than trialing additional NSAIDs 5
• For OTC low-dose formulations (12.5 mg): Maximum 5 days for pain, 3 days for fever 6

Important Formulation Note

Different diclofenac formulations (enteric-coated, extended-release, immediate-release) are NOT bioequivalent even at the same milligram strength 1

Common Pitfalls to Avoid

• Never exceed 150 mg/day by any route 5, 2, 1
• Never combine with anticoagulants without close monitoring (INR increases up to 15%, bleeding risk triples) 5
• Do not assume equivalence between oral and injectable formulations when switching routes 1
• Avoid general gastroprotection policies for all patients; target high-risk groups specifically 4