Etoricoxib exerts its therapeutic effects through selective inhibition of the cyclooxygenase-2 (COX-2) enzyme. Its key mechanisms include:

1. Selective COX-2 Inhibition:
   • Etoricoxib selectively inhibits the COX-2 enzyme, which is induced during inflammation and is responsible for the production of prostaglandins that mediate pain, inflammation, and fever.
   • Unlike non-selective NSAIDs, etoricoxib has minimal effect on the COX-1 enzyme, which protects the gastric mucosa and regulates platelet function.
2. Reduction of Prostaglandin Synthesis:
   • By inhibiting COX-2, etoricoxib reduces the production of prostaglandins, leading to decreased inflammation, pain, and fever.
3. Minimal Gastrointestinal Effects:
   • Due to its selective action on COX-2, etoricoxib has a lower risk of gastrointestinal side effects compared to non-selective NSAIDs.

Etoricoxib is approved for a variety of clinical conditions, including:

1. Osteoarthritis:
   • Management of pain and inflammation associated with osteoarthritis.
2. Rheumatoid Arthritis:
   • Treatment of pain and inflammation in rheumatoid arthritis.
3. Acute Gout:
   • Management of acute gouty arthritis.
4. Ankylosing Spondylitis:
   • Treatment of pain and inflammation in ankylosing spondylitis.
5. Off-Label Uses:
   • Management of chronic pain conditions (e.g., low back pain).
   • Adjunctive therapy for dental pain.

The dosage of etoricoxib varies depending on the indication, patient response, and tolerability. The following dosing guidelines are based on the British National Formulary (BNF) and clinical pharmacology references:

1. Osteoarthritis:
   • Adults: 30–60 mg once daily.
2. Rheumatoid Arthritis:
   • Adults: 90 mg once daily.
3. Acute Gout:
   • Adults: 120 mg once daily for up to 8 days.
4. Ankylosing Spondylitis:
   • Adults: 90 mg once daily.

Important Considerations:

• Etoricoxib is available in oral tablets.
• Dose adjustments may be necessary for patients with hepatic or renal impairment.
• Etoricoxib should be taken with food to minimize gastrointestinal side effects.

Etoricoxib is generally well-tolerated, but it is associated with a range of side effects, some of which can be serious. Common side effects include:

1. Gastrointestinal:
   • Nausea, dyspepsia, and abdominal pain.
   • Gastric ulcers and gastrointestinal bleeding (less common than with non-selective NSAIDs).
2. Cardiovascular:
   • Increased risk of myocardial infarction and stroke, particularly with long-term use or high doses.
3. Renal:
   • Acute kidney injury and interstitial nephritis (rare).
4. Other:
   • Headache, dizziness, and edema.

Serious Side Effects:

• Cardiovascular Events: Increased risk of thrombotic events, such as myocardial infarction and stroke.
• Hypersensitivity Reactions: Stevens-Johnson syndrome (SJS) and anaphylaxis (rare).
• Hepatotoxicity: Elevated liver enzymes and, rarely, severe liver damage.

Etoricoxib requires careful monitoring and adherence to specific precautions to ensure patient safety:

1. Cardiovascular Risk:
   • Use with caution in patients with a history of cardiovascular disease. Regular monitoring of cardiovascular health is recommended.
2. Renal Impairment:
   • Use with caution in patients with impaired kidney function. Avoid use in severe renal impairment (CrCl <30 mL/min).
3. Hepatic Impairment:
   • Use with caution in patients with hepatic impairment. Avoid use in severe hepatic impairment.
4. Pregnancy and Lactation:
   • Etoricoxib should be avoided during pregnancy, especially in the third trimester, due to the risk of premature closure of the ductus arteriosus. It is excreted in breast milk, so breastfeeding is generally not recommended.
5. Elderly Patients:
   • Lower doses may be required due to increased sensitivity to side effects, particularly cardiovascular and renal.

Etoricoxib has a significant potential for drug interactions due to its effects on prostaglandin synthesis and metabolism. Key interactions include:

1. Anticoagulants:
   • Etoricoxib may enhance the anticoagulant effects of warfarin, increasing the risk of bleeding.
2. ACE Inhibitors and Diuretics:
   • Etoricoxib may reduce the efficacy of antihypertensive medications and increase the risk of renal impairment.
3. Lithium:
   • Etoricoxib may increase lithium levels, increasing the risk of toxicity.
4. Methotrexate:
   • Etoricoxib may increase the levels of methotrexate, increasing the risk of toxicity.
5. Other NSAIDs:
   • Concurrent use with other NSAIDs increases the risk of gastrointestinal and cardiovascular side effects.

Etoricoxib is the generic name for this medication. It is marketed under various brand names, depending on the country and manufacturer. Some examples include:

• Arcoxia (a well-known brand in the United Kingdom and other regions).
• Etoricoxib Accord.
• Etoricoxib Mylan.
• Etoricoxib Sandoz.