WEDNESDAY, Feb. 21, 2007 (HealthDay News) -- The U.S. Food and Drug Administration has told the manufacturer of an injected asthma drug to add the strongest warning possible to the medication's label.
The new alert for Xolair (omalizumab), marketed by Genentech Inc., draws attention to anaphylaxis as a potential side effect of the medication.
Anaphylaxis is a sudden, potentially life-threatening allergic reaction that can include trouble breathing, tightness in the chest, dizziness, fainting, itching and hives and swelling of the mouth and throat
The FDA has also asked Genentech to update the existing label warning and to provide a Patient Medication Guide with a strengthened warning for anaphylaxis.
Experts did not think the action would affect prescribing patterns greatly, however.
"It is probably going to affect prescribing in a very minor way," said Dr. Andrew Colin, director of pediatric pulmonology at the University of Miami Miller School of Medicine. "This cannot be viewed as a routine medication at this point in time. It's reserved for the severe or resistant patient, so I do not think that these extra precautions are really going to have a huge impact."
"It's still a valuable drug and, like any drug, people can become allergic and have anaphylaxis," added Dr. Len Horovitz, a pulmonary specialist with Lenox Hill Hospital in New York City. "That's not really a shock here."
Xolair was approved in 2003 to treat adults and adolescents 12 years and older with moderate to severe persistent allergic asthma whose symptoms can't be fully controlled with inhaled steroids.
Some 17 million American adults and children suffer from asthma, 60 percent of them from allergic asthma.
According to one study, adding Xolair to a patient's medication regimen helps cut emergency medical visits. It also decreases the rate of asthma exacerbations.
Persistent asthma (as opposed to intermittent asthma) carries a high risk of exacerbations and the need for resultant medical treatment.
In some people, asthma is caused by an allergic reaction gone awry: The immune system stimulates the production of IgE antibodies. Subsequent exposure to the allergen or allergens causes the IgE antibodies to set off an inflammatory response, which leads to the wheezing and other breathing difficulties associated with asthma.
Xolair is a monoclonal antibody that interrupts this potentially life-threatening process at the start. It is the first biologic approved for asthma, and is given by injection once a month.
The drug already has a black box warning for a possible raised risk for malignancies, although that link is not definite, Horovitz said.
"The majority of physicians who prescribe Xolair are allergists or pulmonologists, and most are aware of this potential adverse reaction," said Dr. David Weldon, director of allergy and pulmonary lab services at Scott & White Clinic, in College Station, Texas. "I think more allergists are going to equip patients with EpiPens [anaphylaxis remedies] to be able to utilize them, based upon the black box warning. It would be prudent that anybody who's on Xolair make sure they get one of the commercially available epinephrine sources like an EpiPen."
Although many patients consider the drug only slightly short of a miracle, some cases of anaphylaxis have been reported following administration of the drug. These reactions have occurred at a rate of about one in 1,000 patients, the FDA said.
The new warning discusses the possibility of patients developing anaphylaxis after any dose of Xolair, even if there was no reaction to the first dose. Also, the reaction may occur up to 24 hours after administration of the drug.
"That's a little disturbing, but most asthmatics have EpiPens to use if they were to experience a life-threatening allergic reaction," Horovitz said.
And Yucynthia Jean-Louis, president of the Asthma and Allergy Foundation of America (AAFA), said the group recognizes the importance of new treatments such as Xolair in fighting moderate to severe asthma. "AAFA encourages the companies and the FDA to continue to work together to assure a product label that is in the best interest of patients," she said.
For more details, visit the U.S. Food and Drug Administration.