[Development of fast dissolving sublingual immunotherapy tablet enhancing medication accessibility]

In the overall Japanese population, the prevalence of perennial allergic rhinitis (AR) increased from 18.7% to 24.5% from 1998 to 2019. For Japanese cedar pollen (JCP) induced AR, the prevalence in the same period increased from 16.2% to 38.8% in the general population and from 7.2% to 30.1% in children (5-9 years), indicating a serious problem especially in younger age groups. Allergy immunotherapy (AIT) is an AR treatment modality that induces immune tolerance to allergens by repeated allergen administration and is the only treatment form that reduces symptoms and medication use and provides sustained effect after treatment completion. In Japan, AIT is available primarily as sublingual immunotherapy (SLIT) tablets. Two tablets based on a freeze-dried formulation (a JCP SLIT-tablet, approved 2018, and a house dust mite (HDM) SLIT-tablet, approved 2015), and one tablet based on a compressed formulation (HDM, approved 2015) are available. For SLIT to be effective, the concentration of allergen when solubilized in saliva must be as high as possible for as long as possible within the recommended sublingual holding time (1-2 minutes), parameters that must be supported by the tablet formulation. The characteristics of the freeze-dried and compressed formulations were compared using the HDM SLIT-tablets. Freeze-dried tablets disintegrated immediately and displayed fast and complete HDM allergen release in solvent, while compressed tablets disintegrated more slowly and provided only incomplete allergen release. Freeze-dried SLIT-tablets are believed to provide full mucosal availability of the allergen content during the sublingual holding time, and a low medication burden.