Celebrex (Celecoxib) Pharmacology

Celecoxib is a non-steroidal anti-inflammatory agent drug (NSAID) used to relieve pain, swelling and inflammation in conditions such as osteoarthritis and arthritis.

Mechanism of action

Celecoxib prevents the synthesis of a chemical called prostaglandin by inhibiting an enzyme called cyclooxygenase 2 (COX-2). Prostaglandins are important mediators of pain and inflammation in the body.

Most NSAIDS inhibit the two forms of cyclooxygenase (COX -1 and COX-2) but celecoxib is a selective inhibitor of COX-2. Both COX-1 and COX-2 are involved in converting arachidonic acid to prostaglandin H2, a precursor for prostaglandin and thromboxane.

Celecoxib has a sulfonamide side chain that binds to a hydrophilic region near to the active binding site of COX-2. The accumulation of prostaglandins, particularly prostaglandin E2, causes inflammation, pain and swelling as part of the healing process. Inhibiting the production of these prostaglandins through COX-2 inhibition therefore alleviates this pain and swelling.

Pharmacokinetics – the movement of the drug within the body

When taken as a 200 mg oral dose celecoxib reaches a peak plasma concentration of 705 ng/mL after 3 hours. If the drug is taken with a high fat meal, the peak concentration is achieved around an hour or two later than this and if the drug is taken with antacids containing aluminium and magnesium salts, the plasma concentration falls by around 37%.

Once absorbed from the gut, 97% of the drug binds to proteins in the blood and is transported to the liver where it is broken down and excreted in the feces and urine.

Recommended uses

Celecoxib is recommended for the relief of pain and inflammation in osteoarthritis, rheumatoid arthritis and a condition called ankylosing spondylitis. The drug is also used to manage pain after surgery or injury or due to menstrual cramps.

However, contraindications for the drug include the following factors and conditions:

• Age under 18 years
• Pregnant and breastfeeding mothers
• Allergy to NSAIDs
• Unstable ischemic heart disease
• Peripheral arterial disease
• Heart failure
• Stroke or cerebrovascular disease
• Peptic ulcer
• Gastrointestinal bleeding
• Liver or kidney damage

Possible side effects

Some of the potential side effects of using celecoxib include:

• Cardiovascular events such as heart attack or stroke
• Abdominal bloating, pain, diarrhea and flatulence
• Dizziness
• Swollen ankles, feet and hands
• Sore throat, fever, chills and flu-like symptoms
• Rash and itchy spots
• Severe allergy or anaphylactic shock