Novartis AG will have to wait an extra three months before finding out if US authorities will back its new lung medicine, which would open the way for a potential new blockbuster drug.

The US Food and Drug Administration has asked for more time to review QAB149 in chronic obstructive pulmonary diseases (COPD) after an advisory panel backed use of only the lower dose of the drug, Novartis said.

The FDA did not request any additional data, the Swiss drugmaker said today.

Earlier this month, the FDA advisory panel voted 13-4 to urge approval of the 75 mcg dose of inhaled drug indacaterol, but they voted against the 150 mcg dose as they were not convinced it provided any additional benefit.

The FDA usually follows panel recommendations. A final decision on QAB149, or indacaterol, had been due by April 1st.

Modest sales are forecast for indacaterol as a stand-alone treatment, but analysts say the drug could bring in more than $5 billion a year when combined with another lung therapy. As a result, it is important for Novartis that both doses are approved.

COPD, also known as smoker's cough because smoking is the major cause, causes breathing trouble and chronic coughing and is sometimes fatal.

Reuters