What are the minimum and maximum doses of diclofenac (Nonsteroidal Anti-Inflammatory Drug) sodium?

Diclofenac Sodium Dosing: Minimum and Maximum Doses

For diclofenac sodium, the maximum daily dose is 150 mg administered in divided doses (75 mg every 12 hours for injectable formulations, or 50 mg three times daily for oral formulations), while the minimum effective dose is 25 mg, though 50 mg is more commonly used as the starting dose for acute pain. 1, 2

Maximum Daily Dose

• The absolute maximum daily dose of diclofenac sodium is 150 mg per day, regardless of route of administration (intravenous, intramuscular, or oral). 1, 2
• For injectable diclofenac (IV or IM), this is administered as 75 mg every 12 hours, with a strict minimum interval of 12 hours between doses to minimize adverse effects. 1
• For oral diclofenac sodium, the maximum can be given as 50 mg three times daily. 2
• This 150 mg/day limit is more restrictive than some other NSAIDs and must not be exceeded. 1

Important Caveat on Formulation

• Diclofenac sodium (enteric-coated, delayed-release) has limited efficacy in acute pain and should probably not be used for this indication. 3
• The sodium salt resists dissolution until reaching the duodenum, resulting in slower onset and reduced effectiveness compared to immediate-release formulations. 3

Minimum Effective Dose

• The minimum dose of diclofenac is 25 mg, which has demonstrated efficacy in clinical trials. 4, 5
• For acute pain, 25 mg provides meaningful analgesia with an NNT (number needed to treat) of 2.8 for at least 50% pain relief. 6
• However, 50 mg is the more commonly recommended starting dose for acute pain management, with superior efficacy (NNT 2.3) compared to 25 mg. 2, 3

Dose-Response Relationship

• There is a clear graded improvement in efficacy as doses increase from 25 mg to 100 mg, both for pain relief and duration of action. 3
• 25 mg: NNT 2.8 6
• 50 mg: NNT 2.3 3, 6
• 100 mg: NNT 1.9 3, 6
• Despite better efficacy at higher doses, the maximum daily limit of 150 mg must be respected due to increased risk of gastrointestinal and renal adverse effects. 1

Dosing by Clinical Indication

Acute Pain (Renal Colic, Postoperative Pain)

• First-line: 75 mg IM/IV as a single dose, or 50 mg orally three times daily. 1, 2
• Maximum: 150 mg/day. 1, 2

Acute Crystal-Induced Arthritis

• 150 mg daily for the first 3 days, followed by 75 mg daily for 3 additional days. 1

Chronic Inflammatory Conditions

• Osteoarthritis/Ankylosing Spondylitis: 100-150 mg/day in divided doses. 4
• Rheumatoid Arthritis: 150-200 mg/day in divided doses. 4
• Note: The 200 mg/day dose mentioned in older literature for rheumatoid arthritis exceeds current guideline recommendations and should be avoided. 1, 4

Critical Safety Considerations

• Higher doses carry significantly increased risk of gastrointestinal bleeding, peptic ulceration, and renal toxicity. 1, 2
• Avoid in patients with active peptic ulcer disease, severe heart failure, liver failure, or history of gastrointestinal bleeding. 2
• In renal impairment (CrCl <10 mL/min), consider dose reduction and discontinue if BUN or creatinine doubles. 1, 2
• Monitor blood pressure, renal function (BUN, creatinine), liver function, CBC, and fecal occult blood at baseline and every 3 months in patients on chronic therapy. 1