The inherent uncertainty of drug development was amply demonstrated at GlaxoSmithKline (GSK) after an announcement that trial results for asthma drug Relovair were more mixed than the company had expected. The news sent traders scurrying to book a profit after a long bull run for GSK shares - and the share price fell 4 per cent.
Relovair showed positive data, but the drug might not be much better than Advair, GSK's off-patent blockbuster asthma drug. In that case, doctors won't be minded to move patients to the new medicine in large numbers. While this is a setback, generic drugs makers are reluctant to copy asthma drugs because this class involves investing heavily in hard-to-produce "biosimilar" classes of medicines that regulators are nervous of approving.
