The firm develops new, more effective, forms of existing drugs

Investors, led by shareholder group North Atlantic Value (NAV), said he was behind a strategy of "over-promising on performance but under-delivering."

Skyepharma is conducting a strategic review which could lead to its sale.

"I have decided to resign in the interest of all shareholders," said Mr Gowrie-Smith in a statement.

"It is unfortunate that the short-term interests of a small group of shareholders can cause such disruption to the development of a company where real achievements are often measured in decades," he added.

On Friday NAV said it wanted Bob Thian, chairman of medical devices firm Whatman and Southern Water, installed instead of Mr Gowrie-Smith.

While announcing the departure of its founder, Skyepharma has said it will resist "any attempts to force a candidate onto the board".

Upgraded drugs

Skyepharma focuses mainly on developing new, more effective forms of existing drugs, often by developing new ways of administering them.

Pharmaceutical companies are keen to introduce upgraded versions of their leading products, since this usually extends their patent life.

Mr Gowrie-Smith, who founded Skyepharma in 1996, stepped down from the role of executive chairman to a non-executive chairmanship in 2004.