Diclofenac

1. Introduction

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) used to relieve pain, inflammation, and fever. It inhibits cyclooxygenase (COX) enzymes, reducing the production of prostaglandins, which mediate inflammation and pain. Available in oral, topical, and injectable formulations, it is widely used for musculoskeletal disorders, arthritis, and post-operative pain.

2. Indications

  • Approved Indications:
    • Pain and inflammation associated with musculoskeletal disorders (e.g., osteoarthritis, rheumatoid arthritis).
    • Ankylosing spondylitis.
    • Acute gout flares.
    • Dysmenorrhoea (menstrual pain).
    • Post-operative pain, including dental surgery.
    • Migraine (in specific formulations).
  • Off-Label Uses:
    • Pericarditis (under specialist guidance).

3. Dosage

  • Adults:
    • Oral: 50–75 mg two to three times daily. Maximum: 150 mg/day.
    • Topical (gel): Apply 2–4 g to the affected area 3–4 times daily.
    • Injection: 75 mg intramuscularly once daily (or twice in severe cases, maximum 150 mg/day).
  • Children:
    • Juvenile Arthritis (oral): 1–3 mg/kg/day in divided doses (maximum 150 mg/day).
  • Elderly:
    • Start with the lowest effective dose due to increased sensitivity to side effects.

4. Administration

  • Oral: Take with or after food to minimise gastrointestinal irritation.
  • Topical: Apply to clean, dry skin and avoid broken skin or wounds.
  • Injection: Administer intramuscularly into the gluteal muscle under medical supervision.

5. Forms Available

  • Tablets: 25 mg, 50 mg, 75 mg, 100 mg (extended-release).
  • Gel: 1%, 2%.
  • Injection: 75 mg/3 mL.
  • Suppositories: 50 mg, 100 mg.

6. Side Effects

6.1. Common Side Effects

  • Gastrointestinal discomfort (nausea, dyspepsia).
  • Diarrhoea or constipation.
  • Headache.

6.2. Less Common Side Effects

  • Dizziness.
  • Skin rash (with topical formulations).
  • Photosensitivity.

6.3. Rare but Serious Side Effects

  • Gastrointestinal bleeding or perforation.
  • Cardiovascular events (e.g., heart attack, stroke).
  • Kidney dysfunction (e.g., elevated creatinine, acute renal failure).
  • Hepatotoxicity (elevated liver enzymes, rare liver failure).

7. Warnings

  • Cardiovascular Risk: Long-term use increases the risk of thrombotic events, myocardial infarction, and stroke. Avoid in patients with significant cardiovascular disease.
  • Gastrointestinal Risk: Risk of ulceration, bleeding, and perforation, especially in elderly patients or those with a history of peptic ulcers.
  • Renal Risk: Use cautiously in patients with renal impairment or dehydration.

8. Precautions

  • Avoid in patients with hypersensitivity to NSAIDs, including aspirin.
  • Use cautiously in patients with asthma, as it may exacerbate bronchospasm.
  • Monitor liver and kidney function during prolonged use.
  • Use with caution in elderly patients due to increased susceptibility to side effects.

9. Interactions

  • Drug-Drug Interactions:
    • Anticoagulants (e.g., warfarin): Increased risk of bleeding.
    • Antihypertensives (e.g., ACE inhibitors, diuretics): Reduced efficacy.
    • Corticosteroids: Increased gastrointestinal toxicity.
    • Methotrexate: Increased toxicity due to reduced clearance.
  • Drug-Food Interactions:
    • Food may reduce gastrointestinal irritation but can delay absorption.

10. Monitoring Parameters

  • Gastrointestinal symptoms, especially in patients with a history of ulcers.
  • Blood pressure and cardiovascular status in long-term use.
  • Liver function tests (ALT, AST) and renal function (serum creatinine).

11. Use in Children

  • Approved for juvenile arthritis and certain inflammatory conditions. Dose adjustments are based on body weight.

12. Use in Pregnancy

  • First and Second Trimester: Use only if the benefit outweighs the risk.
  • Third Trimester: Contraindicated due to the risk of premature closure of the ductus arteriosus and foetal renal dysfunction.

13. Use in Elderly

  • Use with caution; start at the lowest effective dose due to increased risk of gastrointestinal and cardiovascular side effects.

14. Use in Kidney Disease

  • Avoid in severe renal impairment (e.g., CrCl <30 mL/min).
  • Monitor renal function closely in patients with mild to moderate impairment.

15. Use in Liver Disease

  • Use cautiously in patients with hepatic impairment.
  • Avoid in patients with severe liver dysfunction or active liver disease.

16. Patient Counselling Points

  • Take diclofenac exactly as prescribed; do not exceed the recommended dose.
  • Take oral forms with food or milk to reduce stomach upset.
  • Avoid alcohol, as it may increase the risk of gastrointestinal side effects.
  • Report signs of gastrointestinal bleeding (e.g., black stools, vomiting blood) or unusual swelling, chest pain, or shortness of breath immediately.
  • For topical use, avoid application on broken skin or near the eyes.
  • Avoid prolonged exposure to sunlight if using topical formulations.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
VoltarenNovartis$15–25 (30 tablets, 50 mg)
CataflamNovartis$12–20 (30 tablets, 50 mg)
Generic DiclofenacVarious$5–15 (30 tablets, 50 mg)
Voltaren GelNovartis$10–20 (50 g, 1%)

18. FAQs (15 Questions)

  1. What is diclofenac used for?
    Diclofenac is used to treat pain, inflammation, and fever in conditions like arthritis, gout, and post-operative pain.
  2. How does diclofenac work?
    It inhibits COX enzymes, reducing prostaglandin production and relieving pain and inflammation.
  3. Can diclofenac be taken long-term?
    Long-term use should be monitored due to risks of gastrointestinal, cardiovascular, and renal side effects.
  4. What are the common side effects of diclofenac?
    Common side effects include nausea, dyspepsia, diarrhoea, and headache.
  5. Can diclofenac cause heart problems?
    Yes, prolonged use increases the risk of heart attack and stroke, especially in high doses.
  6. How should diclofenac be taken?
    Take it with food or milk to reduce gastrointestinal irritation.
  7. Is diclofenac safe in pregnancy?
    It is contraindicated in the third trimester and should be used with caution in the first and second trimesters.
  8. Can children take diclofenac?
    Yes, it is approved for certain conditions like juvenile arthritis, with dose adjustments based on weight.
  9. Can diclofenac be used topically?
    Yes, it is available as a gel for localised pain relief, such as joint or muscle pain.
  10. Can diclofenac cause gastrointestinal bleeding?
    Yes, it can cause bleeding, ulcers, or perforation, especially with long-term use.
  11. Can I drink alcohol while taking diclofenac?
    Alcohol increases the risk of gastrointestinal side effects and should be avoided.
  12. What should I do if I miss a dose?
    Take it as soon as you remember unless it’s close to the next dose. Do not double up.
  13. Does diclofenac interact with other medications?
    Yes, it interacts with anticoagulants, antihypertensives, corticosteroids, and methotrexate.
  14. Can diclofenac be used for migraines?
    Yes, specific formulations are approved for the acute treatment of migraines.
  15. How should diclofenac be stored?
    Store at room temperature, away from light and moisture.