The Food and Drug Administration (FDA) has demanded more data from AstraZeneca Plc regarding its asthma drug Symbicort. The company is seeking approval for Symbicort for the long-term maintenance treatment of asthma in 6-11 year-olds.

Symbicort is already approved for patients aged 12 and over. Shares of the company slipped 1 percent after this decision of FDA. It is also approved for treating for chronic obstructive pulmonary disease, or COPD, in adults.

Food and Drug Administration (FDA) said AstraZeneca had not provided adequate data to establish the appropriate dose or doses of the drug's two components -- budesonide and formoterol -- in this younger age group.

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.

Company officials said: "AstraZeneca is evaluating the CRL and will provide a response to the agency in due course."