COX 1 Inhibitors- NSAIDs, Which NSAIDs are Better, COX 1 or COX 2 Inhibitor, Classification of COX 1 Inhibitors: NSAIDs

Prostaglandin is one of the most active hormone found in all tissues in human body. Prostaglandin participate in contraction and relaxation of smooth muscles as well as activates white blood cells to protect the tissue against the harmful effect of viruses, protozoa and bacteria. Prostaglandin triggers increase blood flow within inflamed tissue. Chronic inflammation is often associated with continuous secretion of prostaglandin that also causes fever and pain. Prostaglandin also protect mucosal membrane of stomach and intestine. Prostaglandin secretion is triggered by Cyclooxygenase 1 and 2 enzymes, Cyclooxygenase enzyme converts arachidonic acid to prostaglandin. There are 2 cyclooxygenase enzyme known as cyclooxygenase 1 (COX 1) and cyclooxygenase 2 (COX 2) enzyme. COX 1 enzyme is found in inflammatory tissue and mucosal membrane. While, COX 2 enzyme is observed only in inflammatory tissue. Inhibition of COX 1 enzyme by non-steroidal anti-inflammatory drugs (NSAIDs) results in decrease secretion of prostaglandin in inflammatory tissue and mucosal membrane. NSAIDS are COX 1 inhibitor and enzyme inhibition causes decrease of fever, pain and increase occurrence of mucosal ulcers. Similarly, inhibition of COX 2 enzyme causes decreased fever and pain but symptoms of ulcers are not observed. COX 2 NSAIDs inhibitors decrease secretion of prostaglandin only in inflammatory tissue and not mucosal membrane. Thus, inhibition of COX 2 enzyme does not cause ulcer formation in stomach and intestine.

NSAIDs are widely used to treat joint pain, body ache, headache, fever and prevent blood clots. NSAIDs are also used to treat inflammation. NSAIDs are the first drug of choice if pain is caused by tissue inflammation. NSAIDs are also prescribed for swelling of mucosa, inflammatory joint disease, joint and bone pain. Skin and subcutaneous infection and injury resulting in inflammation are treated with NSAIDs. NSAIDs are effective for treatment of nociceptive pain as well as neurogenic pain like radicular pain, diabetic pain and sciatica.

The common side effects observed with NSAIDs are abdominal pain and heartburn that is caused by stomach or intestinal ulcer. Occasional bleeding disorder or kidney disease is observed in few cases. Fluid retention may cause hypertension (increase blood pressure). NSAIDs also causes headaches and dizziness. Other side effects observed are tinnitus (ringing ears) and allergic rashes.

Corticosteroids and medications under group of NSAIDS restricts further increase of inflammatory changes within infected or injured tissue. NSAIDs medications are classified as nonsteroidal anti-inflammatory drugs to differentiated from corticosteroid. The NSAIDs and corticosteroids have a different chemical structure and mechanism of action against inflammation are also different. NSAIDs inhibits Cyclooxygenase enzyme resulting in decrease secretion of prostaglandin.

Cyclooxygenase enzyme is also known as COX enzyme. There are two types of COX enzymes, known as COX 1 and COX 2. The cyclooxygenase enzymes are found in epithelial and endothelial cells. Cyclooxygenase enzyme 1 (COX 1) are predominantly found endothelial cells of mucosal membrane. Similarly, COX 2 enzyme are predominantly observed in inflamed tissue following infection, tissue damage or injuries. The active COX 2 enzyme causes increase secretion of prostaglandin in inflamed tissue.

Cyclooxygenase 1 and 2 enzyme triggers conversion of arachnoid acid to prostaglandin within epithelial and endothelial cells. Such chemical conversion of arachnoid acid to prostaglandin is trigger by microbiological action of cyclooxygenase enzyme. COX1 enzymes also regularly secretion of prostaglandin within stomach and intestinal mucosa by stimulating intestinal endothelial cells to secrete prostaglandin that protects the mucosal layer.

COX 1 inhibitors are NSAIDs. NSAIDs antagonizes cyclooxygenase enzyme and suppresses the conversion of arachnoid acid to prostaglandin. Thus, NSAIDs decreases secretion of prostaglandin within inflamed tissue by inhibiting COX 2 enzyme as well as mucosal membrane of stomach and intestine by inhibiting COX 1 enzyme. The decrease prostaglandin secretion within inflamed tissue helps to reduced pain and toxins that causes fever. Same time, decrease secretion of prostaglandin within stomach and intestine causes formation of ulcer and bleeding form ulcer surface since protection of these mucosal membrane by prostaglandin is removed. COX 1 inhibitor NSAIDs inhibits COX 1 enzyme and causes decrease of fever, pain and intensity of inflammation, as well as removes protection of mucosal membrane resulting in ulcer formation followed bleeding from ulcer.

COX 2 inhibitor decreases prostaglandin secretion within inflamed tissue and helps to relieve symptoms like and pain and fever. While COX 1 enzyme inhibitors (NSAIDs) decreases secretion of prostaglandin within inflamed tissue and mucosal membrane. COX 1 enzyme inhibitors thus decreases symptoms of pain and fever but also cause stomach and intestinal ulcers. It seems COX 2 enzyme inhibitors are better since the therapy relives symptoms like pain and fever and also prevents formation of stomach and intestinal ulcer.

Low dose of 81 mg of Aspirin is widely used as a prophylactic blood thinning medication to prevent heart attack. Similarly, ibuprofen and naproxen are very often used for arthritis, joint pain and muscle aches. Aspirin, ibuprofen and naproxen are available over the counter and does not need physician prescription.

COX 1 inhibitors are divided in following 5 groups.

1. Salicylates

   1. Aspirin
   2. Diflunisal
   3. Salsalate

2. Propionic acid derivatives

   1. Ibuprofen
   2. Ketoprofen
   3. Naproxen
   4. Oxaprozin
   5. Fenoprofen

3. Acetic Acid derivatives

   1. Indomethacine
   2. Ketorolac
   3. Sulindac
   4. Etodolac
   5. Nabumetone
   6. Tolmetic

4. Enolic Acid Derivatives

   1. Pyrazolones

      1. Phenylbutazone
      2. Dipirone

   2. Oxycam

      1. Meloxicam
      2. Piroxicam

5. Fenamic Acid Derivatives

   1. Meclofenamate
   2. Mefenamic acid

Also Read:

• What Are NSAIDs? Know The Risk Factors, Side Effects, Complications, Classifications, Symptoms and Treatment Indication
• NSAIDS: A Cause For Peptic Ulcer Disease!
• What are NSAIDS, Know its Mechanism of Action, Medical Conditions It Can Treat
• Best NSAIDs or Nonsteroidal Antiinflammatory Drugs for Pain Relief?
• Salsalate (COX 1 Inhibitors and NSAIDs)

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