WASHINGTON - The Food and Drug Administration has approved an injectable drug from GlaxoSmithKline PLC to treat severe asthma attacks.

The agency on Wednesday cleared Nucala for patients 12 years and older who cannot control their asthma with more conventional drug options.

According to federal figures, more than 22 million people in the U.S. have asthma, leading to more than 400,000 hospitalizations each year. 

Nucala is injected every four weeks by a health care professional in the arm, thigh or abdomen. The genetically engineered antibody is grown in cells from Chinese hamsters and works by reducing levels of white blood cells that contribute to asthma.