ARTHRIX CAPSULE 100 MG

Indications

• Osteoarthritis
• Rheumatoid arthritis
• Acute pain
• Management of chronic pain

Mechanism of action

Colecoxib selectively inhibits cyclooxygenase-2 (COX-2), an enzyme that catalyzes the conversion of arachidonic acid to prostaglandins. Prostaglandins are involved in the inflammatory response, pain signaling, and the maintenance of homeostasis in the gastric mucosa. By inhibiting COX-2, colecoxib decreases the production of these pro-inflammatory prostaglandins, thus alleviating pain and inflammation without significantly affecting the COX-1 enzyme, which is responsible for protecting the gastric mucosa.

Pharmacodynamics

The pharmacodynamics of colecoxib involves its analgesic and anti-inflammatory effects through the inhibition of COX-2. This leads to a reduction in the levels of prostaglandins, which play a crucial role in the development of pain and inflammation. The selectivity for COX-2 offers a therapeutic advantage, as it minimizes the gastrointestinal side effects typical of non-selective NSAIDs, such as ulceration and bleeding. Additionally, colecoxib has been shown to have a favorable effect on joint inflammation in conditions like rheumatoid arthritis.

Pharmacokinetics

Colecoxib is well-absorbed following oral administration, with peak plasma concentrations occurring within 2 to 4 hours. It has a large volume of distribution, indicating extensive tissue binding. The drug is primarily metabolized in the liver via cytochrome P450 enzymes, predominantly CYP2C9, to inactive metabolites. The elimination half-life is approximately 11 hours, allowing for once or twice daily dosing. Renal excretion accounts for a minor route of elimination, with most metabolites being excreted via feces.

Contra-indications

• Hypersensitivity to celecoxib or any of the excipients.
• Active peptic ulcer disease or gastrointestinal bleeding.
• History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
• Severe hepatic impairment.
• Severe renal impairment or patients undergoing dialysis.
• Pregnancy, particularly in the third trimester.

Adverse effects

• Gastrointestinal discomfort or distress, including nausea and diarrhea.
• Headache, dizziness, or fatigue.
• Increased risk of cardiovascular events, such as heart attack or stroke.
• Renal impairment or failure.
• Skin reactions, including rash or itching.
• Hepatic enzyme elevation.

Interactions

• Increased risk of gastrointestinal bleeding when used with other NSAIDs or anticoagulants.
• May enhance the effects of antihypertensive medications.
• Caution with concomitant use of methotrexate, as it may increase toxicity.
• May alter the pharmacokinetics of other drugs metabolized by CYP2C9.

Precautions

• Use with caution in patients with a history of cardiovascular disease.
• Monitor renal function in patients with pre-existing renal disease.
• Assess liver function before initiation in patients with liver disease.
• Consider cardiovascular risk factors before prescribing, especially in long-term use.

Pregnancy

Celecoxib is contraindicated in pregnancy, particularly during the third trimester due to potential harm to the fetus and complications during delivery.

Breast-feeding

Celecoxib is excreted in breast milk; caution is advised when administering to nursing mothers.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Formulations

• Capsules: 100 mg, 200 mg.