While AstraZeneca will have welcomed the news that its Crestor anti-cholsterol drug has been approved for atherosclerosis, or hardening of the arteries, it hardly represents a panacea for the company's wider woes.

Earlier this week, the company suffered a blow in a clinical trial of Crestor in heart failure patients, which showed the drug was no better than a placebo. It is also facing a challenge from a Canadian generic drug manufacturer to patents on the medicine.

More fundamentally, AstraZeneca is simply running out of blockbuster products. The patents on some of its top-selling drugs such as stomach acid treatment Nexium are set to expire over the next few years and it does not yet have any promising drugs in late-stage development that are likely to replace them.

While it has acquired a lot of interesting early stage technology over the past two years by buying companies like CAT and Medimmune, it could be well into the next decade before any of their products start to generate serious revenues.

AstraZeneca is thus facing some very lean years and is struggling to address this issue by cutting staff and embarking on an aggressive restructuring drive.

In addition, AstraZeneca - in common with all drug companies - is facing an increasingly tough operating enviornment in the US, easily the world's largest market for medicines, for political reasons.

The increasingly tough regulatory approach taken by the FDA is making it harder and more expensive to have new drugs approved and a new political push to use more generic drugs is also undermining corporate profits.

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