Aspirin

Aspirin
IUPAC name	2-acetyloxybenzoic acid
Tradename	Bayer Aspirin, many others
Drugs.com	monograph, aspirin
Routes of administration	By mouth, rectal
Bioavailability	80–100%
Protein bound	99.6%
Metabolism	Liver (CYP2C19)
Elimination half-life	2–3 hours (low dose); 15–30 hours (high dose)
Excretion	Urine (80–100%)

Aspirin. Also known as acetylsalicylic acid, it is one of the most widely used medications globally for its analgesic, antipyretic, and anti-inflammatory properties. Its development is rooted in the use of willow bark, an ancient remedy documented by civilizations like ancient Greece and referenced by Hippocrates. The modern drug was first synthesized in 1897 by chemist Felix Hoffmann at the German pharmaceutical company Bayer, which began marketing it in 1899. Beyond its classic uses, it plays a critical role in preventing cardiovascular events such as myocardial infarction and ischemic stroke due to its antiplatelet effects.

History

The therapeutic precursor, salicylic acid, was derived from the bark of the willow tree, a remedy known to ancient physicians including Hippocrates and later figures like Galen. In the 19th century, efforts to mitigate the compound's severe gastrointestinal irritation led to chemical modifications. At Bayer, chemist Felix Hoffmann, under the direction of Heinrich Dreser, successfully acetylated salicylic acid in 1897, creating a better-tolerated form. Bayer secured a patent and launched an aggressive marketing campaign under the trademarked name, making it one of the first globally marketed pharmaceuticals. Its use expanded dramatically during events like the 1918 influenza pandemic and it became a staple in medicine cabinets worldwide, with its production and ownership affected by the Treaty of Versailles.

Medical uses

It is primarily employed for the treatment of pain, fever, and inflammatory conditions such as rheumatoid arthritis. A landmark application, established through studies like the Physicians' Health Study, is the long-term, low-dose administration for the secondary prevention of myocardial infarction and ischemic stroke, as it irreversibly inhibits platelet aggregation. Guidelines from organizations like the American Heart Association and the U.S. Preventive Services Task Force also address its role in primary prevention for select individuals. Additionally, it is used in the acute management of ST-elevation myocardial infarction and may be recommended for preventing pre-eclampsia in high-risk pregnancies by groups like the American College of Obstetricians and Gynecologists.

Adverse effects

The most common risks involve the gastrointestinal tract, ranging from dyspepsia to ulcers and bleeding, exacerbated by concomitant use of other NSAIDs or corticosteroids. A serious, though rare, condition associated with pediatric use during viral illnesses is Reye syndrome, which affects the liver and brain. Allergic reactions can occur, particularly in individuals with asthma or nasal polyps. Due to its antiplatelet action, it increases the risk of hemorrhagic stroke and other bleeding events. These risks have led to revised recommendations from regulatory bodies like the Food and Drug Administration and the European Medicines Agency regarding its use in primary prevention.

Pharmacology

After oral administration, it is rapidly absorbed in the stomach and proximal small intestine, with its bioavailability influenced by formulation and gastric pH. It works primarily by irreversibly acetylating a serine residue on the enzyme cyclooxygenase, inhibiting the production of prostaglandins and thromboxane A2. This action underpins its triple effects: analgesia (via peripheral and central actions), antipyresis (acting on the hypothalamus), and anti-inflammatory properties. Its unique, irreversible inhibition of cyclooxygenase-1 in platelets provides the long-lasting antiplatelet effect crucial for cardiovascular protection, distinguishing it from other NSAIDs.

Chemistry

Chemically designated as acetylsalicylic acid, it is an acetyl derivative of salicylic acid. It is a white, crystalline, weakly acidic substance with a melting point of approximately 136 °C. It is poorly soluble in water but dissolves readily in organic solvents like ethanol or chloroform. In moist environments, it undergoes hydrolysis back to salicylic acid and acetic acid, which can be detected by a vinegar-like odor. Its synthesis typically involves the reaction of salicylic acid with acetic anhydride, often catalyzed by an acid like sulfuric acid, a process scalable for industrial production by companies like Bayer.

Society and culture

It is listed on the World Health Organization's List of Essential Medicines and is available as a generic medication, making it extremely affordable globally. Cultural iconography is strong, with the brand Bayer Aspirin being one of the most recognized. Its role in preventive medicine has been popularized through public health campaigns by institutions like the American Heart Association. The drug's history is featured in exhibits at museums such as the Deutsches Museum in Munich. Legal battles over patent rights and trademark, particularly after World War I, shaped the early pharmaceutical industry, and it remains a subject of ongoing clinical research by entities like the National Institutes of Health.

Category:Drugs