Acetylsalicylic acid (more commonly known as Aspirin) By Viktor Polites

History  Salicin, derived from Willow Bark, had been used since the time of the ancient Greek philosopher, Hippocrates, to relieve dull aches and pains.  Salicin is metabolized by the body to produce salicylic acid, which has similar anti-inflammatory properties to that of aspirin, but causes extreme stomach discomfort, even stomach bleeding.  In 1897, Felix Hoffman, a researcher from Bayer AG synthesized acetylsalicylic acid from salicin derived from meadowsweet.  In 1919, Bayer AG lost Aspirin as a registered trademark in the US, the UK, France, and Russia due to war reparations imposed by the Allies.

Chemical Structure  Formula: C 9 H 8 O 4  Systematic name: 2- acetoxybenzoic acid  Has a benzene ring backbone  Carboxylic acid  Ester group on the 2nd carbon in benzene ring.

Physical Properties  Density: 1.40 g/cm 3  Melting Point: 135 °C  Boiling Point: 140 °C  Solubility in Water: 3 mg/mL at 20 °C

Chemical Properties  Acetylsalicylic acid slowly decomposes by hydrolysis into acetic and salicylic acids in the aqueous medium.  Hydrolysis of acetylsalicylic acid is accelerated in solutions of ammonium acetate, or acetatates, carbonates, citrates, or hydroxides of the alkali metals.  Acetylsalicylic acid is a weak acid with an acid dissociation constant, Ka, of 3.2 x 10^-4.

Synthesis  Acetylsalicylic acid is synthesized by producing an esterification reaction of salicylic acid with acetic anyhydride. The products of this reaction are acetylsalicylic acid, and acetic acid.  Dilute sulfuric acid and sometimes phosphoric acid are used as catalysts.  Overall Reaction: Salicylic acidacetic anhydride acetylsalicylic acidacetic acid

Synthesis  Reaction Mechanism:

Uses  Aspirin is a non-steroidal anti-inflammatory drug (NSAID).  Aspirin is used primarily to reduce inflamation, to alleviate fevers, and to alleviate mild aches and pains.  For treatment of post-surgery pain, Ibuprofen has been shown to be more effective than aspirin.  Aspirin is the primary drug used to treat migraines.  Aspirin, taken over a long period of time and in low doses, significantly reduces the risk of heart attack and stroke.  Additionally, low doses of aspiring taken over a long period of time have recently been shown to dramatically reduce the mortality rate in cancer patients.

How Aspirin Works  Aspirin’s anti-inflamatory, pain relieving, fever relieving, and anti- coagulant properties arise from its ability to decrease the body’s production of prostoglandins and thromboxanes.  Aspirin inhibits the production of prostoglandins and thromboxanes by inactivating cyclooxygenase enzymes by acetylation of their serine residues.  Unlike other NSAID’s such as ibuprofen, aspirin’s inactivation of cyclooxygenase is irreversible.  Prostoglandins are responsible for delivering pain responses, causing fever, and causing inflamation.  Thromboxanes are primarily responsible for causing blood to coagulate. Inhibition of thromboxanes by low doses of aspirin reduces the risk of heart attack or stroke.

Cyclooxygenase-2 inactivated by Aspirin

Biosynthesis of Prostacyclin and Thromboxane

Adverse Side Effects  Aspirin increases the risk of gastrointestinal bleeding.  Aspirin increases the risk of bleeding in hemophilic patients.  In high doses over a long period of time, aspirin causes iron-deficiency anemia.  Aspirin administered to children with viral infections can cause Reye’s syndrome, which is characterized by brain injury and by fat buildup in the liver.  Those who have an intolerance to salicylate experience hives when they take aspirin.

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