Introduction- What is Etoricoxib?
Etoricoxib, also known as Arcoxia1, is more commonly known as a non-steroidal anti-inflammatory drug (NSAID), or as a cyclo-oxygenase-2 inhibitor (COX-2). Therapeutically, it is specified for the ‘symptomatic relief” of conditions such as osteoarthritis (OA), rheumatoid arthritis (RA), ankylosing spondylitis2,3, and overall for their analgesic and anti-inflammatory properties. Arthritis is a chronic disease affecting up to ten million people in the UK. Approximately 14% of all primary care visits are for musculoskeletal pain or dysfunction, and can be extremely debilitating if not treated in an efficient manner2, 4. However, Etoricoxib is not the first ...view middle of the document...
1) Osteoarthritis: Given orally 30 mg daily. The dose should not exceed 60 mg daily.
2) Rheumatoid arthritis: Given orally 90 mg daily. The dose should not exceed 90 mg daily.
3) Acute Gouty Arthritis: Given orally 120mg daily. The dose should not exceed 120 mg.
NSAIDs work commonly by blocking the action of cyclooxygenase isoenzymes (COX-1, COX-2). This consequently blocks the production of prostaglandins which are responsible for inflammation9. The COX-2 isoenzyme is the particular enzyme that produces prostaglandins, which cause inflammation. On the other hand, COX-1 isoenzymes do not produce these inflammatory prostaglandins, but have various other effects. An important effect is maintaining a healthy stomach and intestinal lining9. Traditional non-selective NSAIDs block the action of both COX-1 and COX-2. These can lead to harmful side effects such as intestinal damage and peptic ulcers, amongst others. NSAIDs are commonly prescribed with a PPI to counteract these harmful side effects. In comparison to the other NSAIDs, Etoricoxib is an orally active, selective COX-2 inhibitor2. It does not inhibit the cyclooxygenase-1 isoenzyme. Therefore it simply lowers the prostaglandin production, consequently meaning that there are fewer chances of stomach-related side effects9.
Figure 1- Mechanism of non-steroidal anti-inflammatory drugs6
Etoricoxib has a unique chemical structure when compared with other similar COX-2 inhibitors. This is potentially the reason as to why Etoricoxib has better oral bioavailability and half-life in contrast to other COX-2 inhibitors such as ‘Celecoxib’, or ‘Valdecoxib’6. Preclinical studies have shown that Etoricoxib is not genotoxic or teratogenic in reproductive toxicity studies, and hence is safe to consume6.
Figure 2: Structure of different selective coxibs6
Absorption: Etoricoxib is given orally and is well absorbed. As mentioned earlier, it has a very high availability of approximately 100%. Consuming the dose with food has no effect on the extent of absorption, but it decreases the rate of absorption by 36%.2
Distribution: Etoricoxib is distributed at an even rate in humans. Animal studies done on rats show that Etoricoxib crosses their placenta and blood-brain barrier2.
Metabolism: Etoricoxib is rapidly metabolised in the body, and is catalysed by the CYP enzyme2.
Elimination: As most of the drug is metabolised, a study done showed only 2% of the drug recovered in the body as the original unchanged drug. Elimination usually occurs through renal excretion2.
Caution and Contra-indications
The blood pressure should be monitored before treatment. Caution should be taken when the drug is given to elderly patients, patients with a history of ulcers or intestinal problems, diabetics, smokers or people with a history of medical allergies. The drug is also contra-indicated in inflammatory bowel disease and uncontrolled hypertension. ...