Days after regulators in the USA gave the green light to Grastek, Merck & Co has bagged approval for another pollen allergy tablet.

The US Food and Drug Administration has approved Ragwitek, licensed from Denmark's ALK-Abello, the first allergen extract administered under the tongue to treat short ragweed pollen induced allergic rhinitis, with or without conjunctivitis in adults.

Ragwitek contains an extract from short ragweed (Ambrosia artemisiifolia) pollen and the tablet is taken once-daily by placing it sublingually, where it rapidly dissolves. Treatment is started 12 weeks before the start of ragweed pollen season and continued thereafter; ragweed is the second most common pollen allergy in the USA.

The first dose is taken in a healthcare professional’s office where the patient is to be observed for at least 30 minutes for potential adverse reactions, the FDA noted, and can then be taken at home. The approval of Ragwitek "offers millions of adults living with ragweed pollen allergies in the USA an alternative to allergy shots", noted Karen Midthun, director of the FDA’s Center for Biologics Evaluation and Research.

The approval is based in part on trials which showed that during treatment for one ragweed pollen season, patients who received Ragwitek experienced a 26% reduction in symptoms and the need for medications compared to those on placebo. Its label will include a boxed warning to inform that severe allergic reactions, some of which can be life-threatening, can occur.

Earlier this week, the FDA approved Grastek, another sublingual immunotherapy but for grass allergy, which was also developed by ALK. The latter and Merck are also working on a third allergy pill, the house dust mite SLIT-tablet, which is in Phase III.