Acetylsalicylic acid

= Acetylsalicylic Acid =

Introduction

Acetylsalicylic acid, commonly known as aspirin, is a widely used medication with analgesic, antipyretic, and anti-inflammatory properties. It is one of the most commonly used drugs globally and has been in use for over a century. Aspirin is also used in low doses to reduce the risk of heart attack and stroke.

History

The use of willow bark, which contains salicin, dates back to ancient times for its pain-relieving properties. In the 19th century, chemists began to isolate and modify salicylic acid to reduce its gastrointestinal side effects. In 1897, Felix Hoffmann, a chemist at Bayer, synthesized acetylsalicylic acid, which was marketed as "Aspirin."

Chemical Structure

Acetylsalicylic acid is an ester of salicylic acid. Its chemical formula is C₉H₈O₄, and it has a molecular weight of 180.16 g/mol. The structure consists of a benzene ring with an acetyl group (CH₃CO) and a carboxyl group (COOH) attached.

Mechanism of Action

Aspirin works by irreversibly inhibiting the enzyme cyclooxygenase (COX), which is involved in the synthesis of prostaglandins and thromboxanes. By inhibiting COX-1 and COX-2, aspirin reduces inflammation, pain, and fever. The inhibition of thromboxane A2 synthesis in platelets leads to its antiplatelet effects.

Pharmacokinetics

Aspirin is rapidly absorbed from the gastrointestinal tract, with peak plasma concentrations occurring within 1-2 hours. It is hydrolyzed to salicylic acid, which is further metabolized in the liver. The elimination half-life of aspirin is about 15-20 minutes, while that of salicylic acid is 2-3 hours.

Clinical Uses

Analgesic and Antipyretic

Aspirin is used to relieve mild to moderate pain and to reduce fever. It is effective in conditions such as headaches, muscle aches, and arthritis.

Anti-inflammatory

In higher doses, aspirin is used for its anti-inflammatory effects in conditions like rheumatoid arthritis and osteoarthritis.

Cardiovascular

Low-dose aspirin is used for its antiplatelet effects to prevent myocardial infarction, stroke, and other thromboembolic events in at-risk individuals.

Side Effects

Common side effects of aspirin include gastrointestinal irritation, bleeding, and allergic reactions. Chronic use can lead to peptic ulcers and renal impairment. Aspirin should be used with caution in patients with asthma or a history of gastrointestinal bleeding.

Contraindications

Aspirin is contraindicated in individuals with hypersensitivity to NSAIDs, active peptic ulcer disease, and in children with viral infections due to the risk of Reye's syndrome.

Drug Interactions

Aspirin can interact with other medications such as anticoagulants, increasing the risk of bleeding. It may also reduce the effectiveness of antihypertensive drugs and compete with other NSAIDs for protein binding sites.

Conclusion

Acetylsalicylic acid remains a cornerstone in the management of pain, inflammation, and cardiovascular disease prevention. Despite its long history, ongoing research continues to explore new therapeutic uses and formulations to enhance its efficacy and safety profile.

References

• Vane, J. R., & Botting, R. M. (2003). The mechanism of action of aspirin. Thrombosis Research, 110(5-6), 255-258.
• Patrono, C., & Baigent, C. (2019). Low-dose aspirin for the prevention of atherothrombosis. New England Journal of Medicine, 381(25), 2529-2540.
• Rainsford, K. D. (2004). Aspirin and related drugs. CRC Press.