May 14, 2018
No doubt you’ve taken me for pain.
What molecule am I?
Image of Ibuprofen 3D Image of Ibuprofen

Ibuprofen is a frequently used over-the-counter drug for treating pain, inflammation, and fever. It is a relatively simple molecule that was discovered and developed in the 1950s and 1960s at Boots Pure Drug in Nottingham, UK (now Boots UK in Beeston). The initial British patent on ibuprofen and a long list of similar compounds was awarded to John Nicholson and Stewart Adams of Boots in 1964.

The trivial name ibuprofen comes from fragments of its chemical name, (±)-2-(p-isobutylphenyl)propionic acid. As the (±) implies, the article of commerce is racemic. The images show the more biologically active (S)-enantiomer. Ibuprofen is sold under a large number of trade names; Advil and Motrin are the most common in the United States.

In addition to its common uses, ibuprofen has been used to treat inflammatory diseases such as rheumatoid and juvenile idiopathic arthritis. But it is not without its risks: patients with cardiovascular disease, hypertension, and gastrointestinal disorders are cautioned against taking it. Ibuprofen also is contraindicated when individuals consume alcohol or low-dose aspirin.

Ibuprofen hazard information

GHS classification*: acute toxicity, oral, category 4
H302—Harmful if swallowed 

*Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

Ibuprofen fast facts

CAS Reg. No.15687-27-1
Molar mass206.28 g/mol
Empirical formulaC13H18O2
AppearanceColorless crystals 
Melting point75–77 ºC
Water solubility21 mg/L

MOTW update

Clothianidin, imidacloprid, and thiamethoxam were the Molecules of the Week for February 17, 2014, August 25, 2014, and October 15, 2012, respectively. All three are neonicotinoid pesticides, and all three have been found to contribute to the worldwide die-off of honeybees. Use of these pesticides has been gradually restricted during the past several years, but now the European Union is about to ban them from all outdoor uses. Will the United States follow suit?

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