Naklofen (Diclofenac Sodium)

Diclofenac sodium is used to treat pain and inflammation associated with musculoskeletal and postoperative conditions.

• Mild to moderate pain: provides analgesia by reducing inflammatory mediators, improving patient comfort during acute injury or disease.
• Inflammatory musculoskeletal conditions: decreases swelling and pain in disorders such as osteoarthritis, rheumatoid arthritis, and acute sprains, facilitating mobility.
• Post‑operative pain: helps control pain after surgical procedures, allowing earlier ambulation and reduced reliance on opioid analgesics.
• Acute sprains and strains: reduces localized pain and inflammation, supporting early rehabilitation and functional recovery.

• Diclofenac sodium exerts its anti‑inflammatory and analgesic effects by reversibly inhibiting cyclooxygenase enzymes COX‑1 and COX‑2. This inhibition blocks the conversion of arachidonic acid to prostaglandins, which are key mediators of inflammation, pain, and fever. By lowering prostaglandin synthesis at the site of injury, the drug diminishes peripheral sensitization and reduces the inflammatory response. The effect is localized to inflamed tissues, providing targeted relief while preserving normal prostaglandin functions elsewhere.

Like other NSAIDs, injectable diclofenac may be associated with a range of adverse reactions.

Common Side Effects

• Injection site pain: mild discomfort or erythema at the intramuscular injection site.
• Gastrointestinal upset: nausea, dyspepsia, or abdominal discomfort may occur.
• Headache: transient mild to moderate headache reported by some patients.
• Dizziness: occasional light‑headedness or vertigo, usually self‑limiting.
• Elevated liver enzymes: mild, reversible increases in hepatic transaminases may be observed.

Serious or Rare Side Effects

• Severe gastrointestinal bleeding: ulceration or hemorrhage that can be life‑threatening and requires immediate medical attention.
• Cardiovascular events: increased risk of myocardial infarction or stroke, particularly with prolonged or high‑dose therapy.
• Renal impairment: acute kidney injury or worsening of chronic kidney disease may develop.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis, presenting with extensive rash and mucosal involvement.
• Anaphylaxis: rare systemic allergic reaction characterized by hypotension, bronchospasm, and possible airway compromise.

When using intramuscular diclofenac, clinicians should observe several precautionary measures to minimize risk.

• Assess renal function: evaluate baseline kidney status before initiating therapy.
• Monitor hepatic enzymes: check liver function tests periodically during treatment.
• Evaluate cardiovascular risk: consider history of heart disease or stroke before use.
• Avoid in active ulcer disease: contraindicated in patients with active gastrointestinal ulceration.
• Use lowest effective dose: prescribe the minimal dose needed for symptom control.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Diclofenac sodium can interact with several medicines, altering efficacy or safety.

Major Interactions (Avoid)

• Anticoagulants (e.g., warfarin): increased risk of serious bleeding, requiring close INR monitoring and possible dose adjustment.
• Other NSAIDs or COX‑2 inhibitors: additive gastrointestinal toxicity that can lead to ulceration or bleeding.
• High‑dose aspirin: heightened bleeding tendency and potential for renal impairment when combined.

Moderate Interactions (Monitor Closely)

• ACE inhibitors or ARBs: may reduce renal protective effects and impair kidney function, especially in patients with pre‑existing renal disease.
• Diuretics: potential for reduced diuretic efficacy and electrolyte imbalance, necessitating periodic assessment of fluid and electrolyte status.
• Lithium: diclofenac can raise lithium levels, requiring serum monitoring and possible dose modification.
• Methotrexate: may increase methotrexate toxicity, monitor blood levels and watch for hepatic or bone marrow suppression.