Ibuprofen: from invention to an OTC therapeutic mainstay

Authors


  • Disclosures The author is a consultant and expert witness on the safety of ibuprofen to Reckitt Benckiser and has also consulted on NSAIDs for other pharmaceutical companies. The author does not hold any shares, stocks or options, or any other financial instruments in any pharmaceutical company.

K. D. Rainsford, PhD, FRCPath, FRCPEdin, FSB, FRSC, CChem, CSci, FIBMS, Dr(hc)
Emeritus Professor, Biomedical Research Centre, Faculty of Health & Wellbeing, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK
Tel.: + 44 114 225 3006
Fax: + 44 114 225 2020
Email: k.d.rainsford@shu.ac.uk

Summary

The discovery of ibuprofen’s anti-inflammatory activity by Dr (now Professor) Stewart Adams and colleagues (Boots Pure Chemical Company Ltd, Nottingham, UK) 50 years ago represented a milestone in the development of anti-inflammatory analgesics. Subsequent clinical studies were the basis for ibuprofen being widely accepted for treating painful conditions at high anti-rheumatic doses (≤ 2400 mg/d), with lower doses (≤ 1200 mg/d for ≤ 10 days) for mild–moderate acute pain (e.g. dental pain, headache, dysmenorrhoea, respiratory symptoms and acute injury). The early observations have since been verified in studies comparing ibuprofen with newer cyclo-oxygenase-2 selective inhibitors (‘coxibs’), paracetamol and other non-steroidal anti-inflammatory drugs (NSAIDs). The use of the low-dose, non-prescription, over-the-counter (OTC) drug was based on marketing approval in 1983 (UK) and 1984 (USA); and it is now available in over 80 countries. The relative safety of OTC ibuprofen has been supported by large-scale controlled studies. It has the same low gastro-intestinal (GI) effects as paracetamol (acetaminophen) and fewer GI effects than aspirin. Ibuprofen is a racemate. Its physicochemical properties and the short plasma-elimination half-life of the R(-) isomer, together with its limited ability to inhibit cyclo-oxygenase-1 (COX-1) and thus prostaglandin (PG) synthesis, compared with that of S(+)-ibuprofen, are responsible for the relatively low GI toxicity. The R(-) isomer is then converted in the body to the S(+) isomer after absorption in the GI tract. Ex vivo inhibition of COX-1 (thromboxane A2) and COX-2 (PGE2) at the plasma concentrations of S(+)-ibuprofen corresponding to those found in the plasma following ingestion of 400 mg ibuprofen in dental and other inflammatory pain models provides evidence of the anti-inflammatory mechanism at OTC dosages. R(-)-ibuprofen has effects on leucocytes, suggesting that ibuprofen has anti-leucocyte effects, which underlie its anti-inflammatory actions. Future developments include novel gastro-tolerant forms for ‘at risk’ patients, and uses in the prevention of neuro-inflammatory states and cancers.

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