Diclofenac

Brand Names: Voltaren

Drug Class: Nonsteroidal Anti-inflammatory Drug (NSAID)

Overview

Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve pain and inflammation in conditions like osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis. It works by inhibiting cyclooxygenase enzymes, reducing prostaglandin production. Treatment requires careful risk-benefit assessment, using the lowest effective dose for the shortest duration due to cardiovascular, gastrointestinal, and hepatic risks.

Mechanism of Action

Diclofenac inhibits cyclooxygenase (COX-1 and COX-2) enzymes, reducing the synthesis of prostaglandins, which are mediators of inflammation, pain, and fever.

Indications

  • Relief of signs and symptoms of osteoarthritis
  • Relief of signs and symptoms of rheumatoid arthritis
  • Relief of signs and symptoms of ankylosing spondylitis (acute or long-term use)

Common Doses

  • 25 mg
  • 50 mg
  • 75 mg

Dosage

Dosage varies by condition: osteoarthritis (100-150 mg/day in divided doses), rheumatoid arthritis (150-200 mg/day in divided doses), ankylosing spondylitis (100-125 mg/day, typically 25 mg four times daily with an extra dose at bedtime if needed). Use the lowest effective dose for the shortest duration.

Contraindications

  • Known hypersensitivity to diclofenac or any component of the product
  • History of asthma, urticaria, or allergic reactions after taking aspirin or other NSAIDs
  • In the setting of coronary artery bypass graft (CABG) surgery

Side Effects

  • Common: abdominal pain, constipation, diarrhea, dyspepsia, nausea, headache, dizziness, edema, elevated liver enzymes, rash
  • Serious: gastrointestinal bleeding/perforation, myocardial infarction, stroke, hepatotoxicity, renal failure, anaphylaxis, severe skin reactions

Interactions

  • Increased risk of bleeding with anticoagulants (e.g., warfarin), antiplatelet agents (e.g., aspirin), SSRIs, SNRIs
  • Reduced effectiveness of antihypertensives (e.g., ACE inhibitors, diuretics)
  • Increased risk of hepatotoxicity with other hepatotoxic drugs (e.g., acetaminophen)
  • Avoid concurrent use of multiple NSAIDs

Counseling Points

  • Take with food or milk to reduce gastrointestinal upset
  • Report signs of gastrointestinal bleeding (e.g., black stools, abdominal pain), cardiovascular events (e.g., chest pain, shortness of breath), hepatotoxicity (e.g., nausea, fatigue, jaundice), or skin reactions immediately
  • Avoid alcohol and other NSAIDs unless directed by a healthcare provider
  • Use the lowest effective dose for the shortest duration possible