1. Clinical Overview
Etoricoxib is a highly selective, second-generation cyclooxygenase-2 (COX-2) inhibitor, classified as a nonsteroidal anti-inflammatory drug (NSAID). It is prescribed for its potent analgesic, anti-inflammatory, and antipyretic properties. The 120mg strength is primarily indicated for acute gouty arthritis and chronic conditions like osteoarthritis and rheumatoid arthritis requiring higher anti-inflammatory effect. It offers the advantage of once-daily dosing due to its long half-life and is associated with a lower risk of gastrointestinal (GI) adverse events compared to non-selective NSAIDs, though it carries a class-related increased risk of cardiovascular (CV) thrombotic events.
| Onset | Duration | Bioavailability |
|---|---|---|
| Approximately 24 minutes for initial analgesic effect; maximum anti-inflammatory effect observed within 4-7 days of continuous therapy. | Approximately 22-24 hours, permitting once-daily dosing. | Approximately 100% following oral administration. |
2. Mechanism of Action
Etoricoxib selectively inhibits the enzyme cyclooxygenase-2 (COX-2), which is induced during inflammation and is responsible for the synthesis of prostanoids (prostaglandins, prostacyclin, thromboxane). By inhibiting COX-2, it reduces the production of prostaglandin E2 (PGE2) at the site of inflammation, thereby exerting anti-inflammatory, analgesic, and antipyretic effects. Its high selectivity (COX-2:COX-1 ratio >106) results in minimal inhibition of constitutively expressed COX-1 in the gastrointestinal tract and platelets, leading to a better GI safety profile and no effect on platelet aggregation.
3. Indications & Uses
- Acute Gouty Arthritis
- Osteoarthritis
- Rheumatoid Arthritis
- Ankylosing Spondylitis
4. Dosage & Administration
Adult Dosage: Osteoarthritis: 60 mg once daily. Rheumatoid Arthritis: 90 mg once daily. Ankylosing Spondylitis: 90 mg once daily. Acute Gouty Arthritis: 120 mg once daily for a maximum of 8 days. Acute Pain/Primary Dysmenorrhea: 120 mg once daily for a maximum of 3 days.
Administration: Can be taken with or without food. Food may delay absorption but does not significantly affect overall bioavailability. Swallow the tablet whole with a glass of water. Do not crush or chew. For acute gout, the 120mg dose should be used only for the acute flare duration (max 8 days), then the dose should be reduced or discontinued.
5. Side Effects
Common side effects may include:
- Dyspepsia/Heartburn
- Nausea
- Abdominal Pain
- Diarrhea
- Flatulence
- Headache
- Dizziness
- Peripheral Edema
- Hypertension
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Warfarin/Acenocoumarol | Increased risk of bleeding due to potential pharmacodynamic interaction (no PK effect on INR, but anti-inflammatory effect may mask signs of bleeding). | Major |
| Aspirin (low-dose cardioprotective) | Concomitant use increases risk of GI ulceration and bleeding without added therapeutic benefit. Etoricoxib does not inhibit platelet aggregation. | Major |
| Lithium | Etoricoxib may decrease renal lithium clearance, leading to increased lithium plasma levels and risk of toxicity. | Major |
| Methotrexate | NSAIDs may reduce renal excretion of methotrexate, increasing its blood levels and risk of hematologic and GI toxicity, especially with high-dose methotrexate. | Major |
| Diuretics (Furosemide, Thiazides) | Reduced diuretic and antihypertensive efficacy. Increased risk of renal impairment due to decreased prostaglandin-mediated renal blood flow. | Moderate |
| ACE Inhibitors (Ramipril, Enalapril) / ARBs (Losartan) | Reduced antihypertensive efficacy. Increased risk of renal impairment, especially in volume-depleted patients. | Moderate |
| Ciclosporin, Tacrolimus | Increased risk of nephrotoxicity. | Moderate |
| SSRIs/SNRIs (Fluoxetine, Venlafaxine) | Increased risk of upper GI bleeding. | Moderate |
| Corticosteroids (Prednisolone) | Increased risk of GI ulceration and bleeding. | Moderate |
| Rifampicin | Strong CYP3A4 inducer; may decrease etoricoxib plasma levels, reducing efficacy. | Moderate |
| Ketoconazole, Itraconazole | Strong CYP3A4 inhibitors; may increase etoricoxib plasma levels. Clinical significance unclear but monitor for adverse effects. | Minor |
7. Patient Counselling
- DO take exactly as prescribed by your doctor, at the lowest effective dose for the shortest possible time.
- DO inform all your doctors and dentists that you are taking etoricoxib before any surgery or new prescription.
- DO report any history of heart disease, stroke, stomach ulcers, bleeding problems, high blood pressure, or kidney/liver disease to your doctor.
- DONT take if you are pregnant (especially last 3 months) or planning pregnancy without consulting your doctor.
- DONT take with other over-the-counter NSAIDs (like ibuprofen, naproxen, diclofenac) or aspirin without medical advice.
- DONT crush, chew, or break the tablet. Swallow it whole with water.
- DONT use for fever in children or adolescents under 16 years.
8. Toxicology & Storage
Overdose: Symptoms may include lethargy, drowsiness, nausea, vomiting, epigastric pain, gastrointestinal bleeding, hypertension, acute renal failure, respiratory depression, coma, and anaphylactoid reactions. Cardiovascular events (MI, stroke) may be exacerbated.
Storage: Store below 30°C. Protect from light and moisture. Keep in the original blister pack or container. Keep out of reach and sight of children. Do not use after the expiry date printed on the pack.