Tree pollen extracts consists mainly of polypeptides and proteins that are not subject to liver metabolism or interaction with CYP enzymes.

Allergen extracts containing tree pollen are used in allergy immunotherapy, to desensitize people that have an allergy to tree pollen. It is administered as a subcutaneous injection. It may be used continuously throughout the season or for up to 3to 5 years for long term efficacy (SPC).

The allergen is presumably taken up by dendritic cells and presented to other cells of the immune system. It is not expected that the allergens is absorbed into the vascular system to any significant extent. No pharmacokinetic studies in animals or clinical studies have been conducted (EMEA, Pfaar 2014, SPC).