Chemistry in your cupboard

Introduction

Nurofen is the brand name under which Reckitt Benckiser sells ibuprofen. Ibuprofen is an over-the-counter remedy for mild to moderate pain which also reduces inflammation and fever. It acts at the site of the pain, rather than in the brain, which is where some other painkillers such as codeine work.

Nurofen is available in a number of formulations, see Figure 1. These include tablets and caplets to be taken by mouth, and gels to be applied to the skin. Also available is Nurofen Express in which ibuprofen, the active ingredient, has been chemically modified to make it more soluble. This means that it is absorbed more quickly by the body and therefore acts faster.

Figure 1: Some of the Nurofen product range

The UK market for over-the-counter painkillers (for headache, toothache, muscular aches, period pain, etc) is worth about £300 million per year.

In the UK, all such medicines are formulated from just four active ingredients - aspirin, paracetamol, codeine and ibuprofen, see Figures 2 and 3. These may be sold separately under their own names, as a branded product (Aspro™, Panadol™, Nurofen™ etc), or as combined preparations containing two or more of these ingredients (Veganin™ contains aspirin, codeine and paracetamol, for example).

Figure 3: Structures of the active ingredients in over-the-counter painkillers

Ibuprofen is a modern addition to the list of over-the-counter painkillers. It was patented by the Boots company in the 1960s and became available without prescription in the UK in the mid-1980s.

Make sure that you can relate the two representations of the active ingredients in over-the-counter painkillers to one another. In the 3D representation, carbon atoms are coloured grey, hydrogen white, oxygen red and nitrogen blue. You may find it helpful to make a model of the active ingredients using a ball and stick modelling kit such as Molymod™.