Spiriva is point at issue

Safety questions over the lung drug Spiriva, marketed by Pfizer Inc and Germany's Boehringer Ingelheim, may arouse a great demand for GlaxoSmithKline Plc's top-seller Advair, according to industry analysts.

The U.S. Food and Drug Administration said late on Tuesday that a meta-analysis of past clinical trials showed Spiriva may increase the risk of stroke, although the risk assessment was not yet conclusive.

Spiriva is used to treat chronic obstructive pulmonary disease, or COPD. Advair is also given for COPD but is typically used second line, once the condition progresses after Spiriva treatment.

"Potential safety concerns over Spiriva could facilitate earlier Advair use in less severe patients," Morgan Stanley analysts wrote in a note.

However, Spiriva is not expected to be pulled from the market and the brokerage said the worst-case scenario for the product was probably a "black box" warning in its labelling. Advair has also suffered from safety problems in the past, which have hit the drug's growth in the asthma-treatment market.

Chronic Obstructive Pulmonary Disease (COPD), also known as chronic obstructive airway diseases (COAD), is a group of diseases characterized by the pathological limitation of airflow in the airway that is not fully reversible. COPD is the umbrella term for chronic bronchitis, emphysema and a range of other lung disorders. It is most often due to tobacco smoking, but can be due to other airborne irritants such as solvents, as well as congenital conditions such as alpha-1-antitrypsin deficiency. It is the 4th leading cause of death in the U.S.