Allergen extracts that have been diluted to intradermal strength are known to lack the stability of concentrated solutions. Since intradermal strength extracts are manufactured as aqueous formulations, these products are prone to protein degradation that may impact their potency through the assigned expiration date.
Studies have demonstrated that using Human Serum Albumin (HSA) as a diluent increases the stability of extracts and can protect against protein degradation as compared with Normal Saline with Phenol (NSP).