AstraZeneca said today that it faces a delay in marketing its asthma treatment Symbicort to young children in the US.

Britain’s second-biggest pharmaceutical group admitted that the US Food and Drug Administration (FDA) is demanding more information on Symbicort, which has been approved for use by children aged over 12 but which the company is also seeking to sell for use by 6 to 11-year-olds.

The FDA says AstraZeneca did not provide adequate data to establish the appropriate dose or doses of the individual components of the drug to such patients.

The news is a blow to AstraZeneca as it had identified Symbicort, its fourth best-selling drug in 2008, as one of its big growth drivers. Sales last year rose by 22 per cent to $2 billion (£1.3 billion).

The company had hoped to market it in the US as a rival product to GlaxoSmithKline’s asthma blockbuster, Advair, which is already used in children as young as four as well as being being used to treat patients suffering chronic diseases such as emphysema.

Symbicort was also approved in February this year for the treatment of patients with conditions, such as chronic bronchitis and emphysema, and AstraZeneca said today that the FDA’s decision would have no impact on these existing patients or on children aged over 12 using it as a treatment for asthma. It added: “AstraZeneca is evaluating the letter from the FDA and will provide a response to the agency in due course.”

The news comes just days after the FDA also raised concerns about allowing Seroquel, AstraZeneca’s depression treatment, to be used more widely. Shares of AstraZeneca dropped by nearly 1 per cent in mid-morning trade.

Simon Mather, of broker Panmure Gordon, said: “We had expected Symbicort to increase market share after approval in children and thus the delay could impact growth of the product going forward.”

Separately, AstraZeneca said the sale of its portfolio of over-the-counter products to rival GlaxoSmithKline has been cleared by Swedish competition authorities. It will receive about $220 million from the sale, which was announced in November last year.

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