Dosing Calculations in Prescribing Sublingual Immunotherapy Drops Using Subcutaneous Immunotherapy Extracts: Implications for Dust Mite and Cat Immunotherapy

Abstract: Sublingual immunotherapy drops (SLIT-D) in the US commonly use extracts manufactured for subcutaneous immunotherapy (SCIT). Using a target daily major allergen dose together with the extract major allergen concentration allows calculation of the extract volume necessary for a maintenance SLIT vial. Although an optimal universal SLIT-D dose has not been established, published dosing recommendations provide practical benchmarks for illustrating these calculations. Using an illustrative target of 15 μg/day in an 8-mL vial, cat extract containing 20 μg/mL Fel d 1 would require 24 mL, whereas dust mite extract containing 60 μg/mL Der p 1 would require 8 mL. This Commentary presents a practical dose-estimation framework based on published allergen concentration data and highlights how lower major-allergen concentrations may constrain SLIT-D formulation. Keywords: allergic rhinitis, asthma, sublingual immunotherapy, dosing, house dust mite, cat allergy