US regulators have agreed to review another of Merck & Co's investigational, dissolvable allergy pills, this time to prevent allergic reactions to ragweed pollen.

The ragweed pollen (Ambrosia artemisiifolia) sublingual allergy immunotherapy has been designed to treat the underlying cause of allergic rhinitis over time, by generating an immune response to help protect against the allergen, as opposed to merely treating its symptoms.

Merck has linked with Danish drugmaker ALK-Abello in North America to develop allergy immunotherapy pills for ragweed pollen, timothy grass pollen and house dust mite, and there is growing excitement over their potential as currently treatments are administered via injection.

The US Food and Drug Administration also recently accepted the firms' Biological License Application for the timothy grass pollen pill, and Merck said it expects the review for both to be completed in the first half of next year.