HealthDay News — There may be good news coming in the form of a pill for the millions of Americans who suffer from ragweed allergy. The FDA’s Allergenic Products Advisory Committee has recommended approving the first ragweed allergy sublingual immunotherapy (SLIT), Ragwitek.

The FDA panel was asked to decide whether the data support the safety and effectiveness of Ragwitek (Merck) for people aged 18 years and older, and whether more studies are needed before making a recommendation to approve the product.

Panel members unanimously agreed on the safety and efficacy of the pill for adults through age 50 years. However, the official vote presented to the committee specified an age range of 18 through 65 years. Two panel members voted against sufficient evidence of efficacy to recommend the treatment for this upper age limit, citing lack of direct evidence from clinical trials, which did not include any patients aged older than 51 years.

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One other member abstained from the vote for this same reason, as well as from the safety vote. All other eight panel members, however, voted that Ragwitek was safe.

Ragwitek is made with an extract of ragweed pollen. Patients begin taking the pill, which is placed under the tongue, 12 weeks before the ragweed pollen season begins and continue to do so through the season’s end.

Last December, the same FDA advisory committee voted unanimously to recommend approval of a similar kind of pill for grass pollen allergies, known as Grastek. Merck is developing that pill in partnership with a European company.

If the FDA follows the advice of its advisory panel, which it usually does, these medications will become the first noninjectable immunotherapies approved for pollen allergies.

Results from clinical trials involving Ragwitek have showed improvement in symptoms and in quality of life among those assigned to the therapy compared with placebo.

Efficacy was established in two phase II/III trails involving 564 and 784 patients, respectively, who were randomly assigned to placebo or ragweed SLIT about four months before the start of ragweed season. In both studies, participants met the primary endpoint of a lower total combined score for rhinoconjunctivitis symptoms and rescue medication use over the peak of ragweed season compared with placebo.

Total combined scores were 26.5% lower with the immunotherapy treatment at the proposed 12 Amb a 1-U dose in the one trial and 24.2% lower with the same dose in the other trial (P=0.0002 and P=0.0015).

In the five studies that looked at safety, treatment-related adverse events were more common with Ragwitek over 28 days (56.5% at the 12 Amb a 1-U dose vs. 37.6% placebo) and 1 year (80.6% vs. 68.4%).

The most common events included oral pruritus, ear pruritus, throat irritation and mouth edema.

Anaphylaxis occurred in two patients assigned to Ragwitek and one placebo patient; seven Ragwitek-treated patients had what were considered systemic reactions.

FDA panel members recommended post-marketing studies to look at the long-term effects and use in other groups including children, racial/ethnic minorities and those with food allergies or a history of anaphylaxis.


  1. FDA Allergenic Products Advisory Committee. FDA Briefing Document: Biologics License Application for Ragwitek. Jan. 28, 2014. Available at