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The Food and Drug Administration has approved Grastek, a sublingual immunotherapy for grass pollen–induced allergic rhinitis with or without conjunctivitis in individuals aged 5-65 years.
Grastek (Timothy Grass Pollen Allergen Extract), manufactured by Merck, was unanimously supported by an FDA advisory committee in December and is the second sublingual oral therapy to be approved by the agency in a few weeks. On April 1, the FDA approved Greer Laboratories’ Oralair, which contains a mixture of freeze-dried extracts from the pollens of five grasses: Kentucky blue grass, orchard, perennial rye, sweet vernal, and Timothy. That product is approved for individuals aged 10-65 years.
H. Zell/Wikimedia Commons
Timothy grass is a common, widespread, long-stemmed grass that is very hardy.
Like Oralair, Grastek has a black box warning of the potential for severe allergic reactions such as anaphylaxis. Grastek is also contraindicated in patients with severe, unstable, or uncontrolled asthma; a history of any severe systemic allergic reaction; a history of any severe local reaction after taking any sublingual allergen immunotherapy; a history of eosinophilic esophagitis; or hypersensitivity to any of the inactive ingredients contained in the product.
Timothy grass (Phleum pratense) is a common, widespread, long-stemmed grass that is very hardy. According to Merck, it is cross reactive with other grasses, including sweet vernal, orchard (also known as cocksfoot), perennial rye, Kentucky blue (also known as June grass), meadow fescue, and redtop.
Before initiating treatment, a patient’s allergy must be confirmed by positive skin test or in vitro testing for pollen-specific IgE antibodies for Timothy grass or cross-reactive grass pollens. Therapy – at a dose of one tablet sublingually daily – is begun 12 weeks before the grass pollen season and should continue through the season. The first dose should be given under a physician’s supervision, according to Merck. Subsequent doses can be taken at home, but patients should also be prescribed injectable epinephrine and given training in how to use the autoinjector.
The company said that Grastek can be taken daily for up to 3 consecutive years.
In trials, the most common adverse reactions for both adult and pediatric patients included oral pruritus, throat irritation, and mouth edema. Adults also experienced ear pruritus.
The FDA approved production of tablets that have a potency of 2,800 Bioequivalent Allergy Units (BAU) of Timothy Grass pollen extract, which will be supplied in 10-tablet blister packs. The agency also said in its approval letter that it will require Merck to create a Medication Guide for distribution to patients because the product "poses a serious and significant public health concern."
Merck also will be required to conduct a 3-year, 10,000-patient postmarketing study to gauge safety, to be completed by about 2017. A second postmarketing study is also required, looking at 10,000 new users who are identified through electronic medical records. That study is also due to be finished by 2017.
Grastek will be available in U.S. pharmacies in late April, according to Merck.
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