What is the Difference Between COX 1 and COX 2 Inhibitors

The main difference between COX 1 and COX 2 inhibitors is that COX 1 inhibitors block the vasoconstrictor activity and platelet aggregation induced by TxA₂, whereas COX 2 inhibitors block vasodilating activity and platelet aggregation by PGI₂.

COX1 and COX2 inhibitors are two types of cyclooxygenase inhibitors that inhibit the prostaglandin synthesis. 

Key Areas Covered

1. What are COX Inhibitors
– Definition, Features, Importance
2. What are COX 1 Inhibitors
– Definition, Features, Importance
3. What are COX 2 Inhibitors
– Definition, Features, Importance
4. Similarities Between COX 1 and COX 2 Inhibitors
– Outline of Common Features
4. Difference Between COX 1 and COX 2 Inhibitors
– Comparison of Key Differences

Key Terms

COX 1 Inhibitors, COX 2 Inhibitors

What are COX Inhibitors

COX inhibitors are drugs used to manage and treat chronic pain syndromes. They are a class of anti-inflammatory drugs. There are three types of COX inhibitors: non-selective nonsteroidal anti-inflammatory drugs (NSAIDs), COX-2 selective nonsteroidal anti-inflammatory drugs (c2s NSAIDs), and aspirin. ibuprofen, naproxen, ketorolac, and indomethacin are examples of NSAIDs. Celecoxib is an example of c2s NSAIDs. The COX enzyme catalyzes the synthesis of prostaglandins from arachnoid acid. COX 1 and COX 2 are the two isoforms of COX. The COX 1 enzyme regulates platelet aggregation, gastric mucosa acid production, and kidney-afferent arteriole vasodilation. In comparison, the COX 2 enzyme increases in inflammation. The COX 2 enzyme is present in the kidney, brain, bone, and female reproductive system.

Figure 1: Aspirin Aluminium

Furthermore, common NSAIDs and aspirin inhibit both COX 1 and COX 2 enzymes. However, c2s NSAIDs only inhibit COX 2. Also, COX inhibitors are commonly administrated orally.  

What are COX 1 Inhibitors

COX 1 inhibitors are the drugs that inhibit the action of COX 1 responsible for gastric mucosa protection, platelet aggregation, and renal electrolyte homeostasis. COX 2 inhibitors are important to treat cancer, cardioprotection, neuro-inflammation, pain, and fever. Aspirin and indomethacin are common examples of COX-1 inhibitors.

What are COX 2 Inhibitors

COX 2 inhibitors are drugs that inhibit the action of COX 2. They are important for treating inflammation and pain in short-term pain and many types of arthritis. Celecoxib is an example of COX 2 inhibitors. Importantly, COX 2 inhibitors do not cause chronic ulceration and acute injury. They are used in treating osteoarthritis, rheumatoid arthritis, juvenile arthritis, ankylosing spondylitis, menstrual pain, familial adenomatous polyposis, and in short-term pain such as sports injuries.

Figure 2: Celecoxib

Similarities Between COX 1 and COX 2 Inhibitors

• COX 1 and COX 2 inhibitors are two COX inhibitors.
• They inhibit the activity of the COX enzyme.
• They are important to treat pain, fever, and inflammatory processes.

Difference Between COX 1 and COX 2 Inhibitors

Definition

COX 1 inhibitors refer to an agent that inhibits the action of the enzyme cox-1 (cyclooxygenase-1). Meanwhile, COX2 inhibitors refer to a type of NSAID used to treat the pain and inflammation of many types of arthritis and other types of short-term pain.

Action

COX 1 inhibitors block the vasoconstrictor activity and platelet aggregation induced by TxA₂, while COX 2 inhibitors block vasodilating activity and platelet aggregation by PGI₂.

Activity

COX 1 inhibitors result in antithrombotic activity, while COX 2 inhibitors produce prothrombotic activity.

Examples

Examples of COX 1 inhibitors are aspirin and indomethacin, while examples of COX 2 inhibitors are celecoxib, etoricoxib, and parecoxib are examples of COX 2 inhibitors.

Conclusion

In brief, COX 1 and COX 2 inhibitors are two NSAIDs that are anti-inflammatory drugs. COX 1 inhibitors inhibit the action of COX 1 enzyme. Thereby, they block the vasoconstrictor activity and platelet aggregation induced by TxA_2. Also, they result in an antithrombotic activity. Aspirin and indomethacin are examples of COX-1 inhibitors. In comparison, COX 2 inhibitors inhibit the action of COX 2 enzyme. They block the vasodilating activity and platelet aggregation by PGI₂. Also, they result in prothrombotic activity. Additionally, they are given to treat pain and inflammation in arthritis. Celecoxib, etoricoxib, and parecoxib are examples of COX2 inhibitors. Therefore, the main difference between COX 1 and COX 2 inhibitors is their action.   

References:

1. Qureshi O, Dua A. COX Inhibitors. [Updated 2023 Mar 2]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. 

Image Courtesy:

1. “Aspirin aluminium” By Benff – Own work (CC-BY SA 4.0) via Commons Wikimedia
2. “Celecoxib” By Acdx – Own Work (Public Domain) via Commons Wikimedia