Competing Interests: SS has consulted for Actelion, Alcon, Amgen, Astra (now Astra-Zeneca), Astra-Zeneca, Aventis, Auxilium, Biosyn, Boehringer Ingelheim, Bracco, Bristol-Myer Squibb, Chiesi, Chiron, Ciba-Geigy (now Novartis), Covance, Dexcel, Elan, Eli-Lilly, Fournier, Glaxo-Wellcome (now GSK), GSK, INO Therapeutics, Janssen, Johnson&Johnson, Jouveinal (now Pfizer), Leiras, Merz, Novartis, Novartis Consumer Health, Novartis Ophthamology, Numico, Orion, Pleaid, Pfizer, Pharmacia (now Pfizer), Pharmapart, Phocus, Roche, Sandoz (now Novartis), Sanofi, Servier, Schein, Schering AG, Shire, Smith-Kline Beecham (now GSK), Statwood, Strakan, Wyeth, Zeneca (now Astra-Zeneca) and possibly other companies he has forgotten about. He used to work for Ciba-Geigy and in consequence owns some shares in Novartis. This note has been prepared without consulting any of the above companies, without their knowledge, and without their express permission, and none of his views should be attributed to any of the above. SS is an academic whose career is furthered by publishing. His views should also not be ascribed to his current employer, Glasgow University.