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Extract Formulations Allergen extracts are available in a variety of formulations. An extract’s formulation directly impacts the stability of the allergenic proteins in solution and therefore the shelf life of the product. The FDA has determined maximum expiration dates for each formulation based on the estimated loss of potency over time. All extracts can be… read more

Dilution Tables Here are some common dilution strategies used when making treatment vials. 5 – Fold Dilution – 5 mL Vials – 1:20 w/v Glycerinated Extract: 1:2 Dilution – 10mL and 5mL Vials: Used for example, when you want to convert a 1:10 w/v into a 1:20 w/v or if you want to convert 10,000… read more

Skin Testing Supplies Once you have reviewed the appropriate procedures, established your diagnostic panel, and ordered your supplies, you are ready to begin testing patients. Most practices will diagnose their patients by skin testing using glycerinated extracts and a sterile, disposable skin test device. Depending on the patient’s clinical history and the allergist’s training and… read more

Effect of Formulation on Stability Below is a figure that shows how expiration dating varies by formulation. For standardized products, these dates were established through FDA-approved testing methods. For non-standardized products, these dates were established by the FDA. For more information on extract formulation, please see the section on Extract Formulations Expiration dates for bulk… read more

Formulation Concern – Phenol Does phenol have a negative impact on extract stability? Many extracts contain phenol (0.4%) as a preservative. There have been some reports that phenol can impact the stability of allergenic extracts. However, more recent data has shown that phenol does not appear to have a significant impact on the long term… read more