Short Ragweed

Generic name: ambrosia artemisiifolia
Dosage form: injection

Short Ragweed Description

INGREDIENTS - Allergenic extract of Short Ragweed pollen is a clear, amber-colored solution prepared from the dry, defatted pollen of Ambrosia elatior. The extract contains the water extractables of the pollen, 0.25% sodium chloride, 0.125% sodium bicarbonate, 0.5% phenol and 50% glycerol by volume. Extract of mixed short-giant ragweed has the same appearance as Short Ragweed pollen extract and contains the same chemical ingredients. It is prepared from equal gram weights of the pollens of Ambrosia elatior and Ambrosia trifida.

STANDARDIZATION - The potency of ragweed pollen extract is based on antigen E, a protein component which is believed to be the most important allergen of Short Ragweed pollen. Extracts of Short Ragweed pollen sold in the U.S. must have a minimum antigen E content of 67.5 units per ml for a 1:20 w/v concentrate. Extracts of mixed short-giant ragweed must have a minimum antigen E content of 33.75 units/ml for a 1:20 w/v concentrate. The importance of antigen E in ragweed allergy is based on the following observations:

1. In vitro studies with antigen E have shown that it is capable of causing histamine release from peripheral leukocytes of ragweed sensitive persons 1.
2. The antigen E content of Short Ragweed pollen extract has been found to correlate with extract potency when measured by skin test response in persons allergic to Short Ragweed pollen 2.
3. Immunotherapy with antigen E has been shown to be comparably effective to whole Short Ragweed pollen extract in reducing symptoms related to ragweed pollen exposure 3.

The weight by volume value shown on the label is a measurement of extract concentration, rather than extract potency. Weight by volume designations may be used to identify dilutions of extract for skin testing and immunotherapy, and are useful from a practical standpoint in identifying the relative strength of a given extract. However, studies have shown that the antigen E content varies in extracts with the same weight by volume concentration 4.

EXPIRATION DATING - Expiration dating is based on the antigen E content of the extract. Extracts containing 50% glycerol by volume have longer dating periods due to the protective effects of glycerol on antigen E 5, 6. The expiration period of aqueous concentrate and saline dilutions of glycerinated concentrate is approximately one-half that of glycerinated extract containing comparable antigen E content.
Ragweed extract sh..