Ambrosia artemisiifolia pollen

Studies have shown that properly performed an interpreted skin tests with ragweed pollen extract are useful in the diagnosis of allergy to ragweed pollen 7, 8, 20, 21. Immunotherapy with the appropriate dosage of short ragweed pollen extract is effective in reducing symptoms of hay fever and asthma resulting from exposure to short ragweed pollen, and it is believed to be effective with extract of giant ragweed, although carefully controlled studies are unavailable. However, clinical observations and known cross reactivity between short and giant ragweed pollens have led to the practice of using a mixture of the two species for skin testing and treatment 22, 23, 24, 25, 26, 27. This form of treatment is recommended for patients who cannot avoid exposure to pollen and who do not obtain satisfactory relief of symptoms from other medications, such as antihistamines.

DIAGNOSIS. If the extract supplied in this package is concentrated product (w/v 1:20), it should not be used for intradermal testing. Concentrated extract may be used for scratch or prick testing providing the patient is not exposed to high levels of ragweed pollen and experiencing pronounced symptoms of hay fever or asthma at the time of testing. Extract for intradermal testing must be diluted to a strength of 0.25 units of antigen E per ml 7. Skin tests should not be performed if the patient has taken antihistamine within 24 hours prior to testing. PROCEDURES Scratch Test: 1 drop of extract concentrate applied to a small scratch or scarification of the volar surface of the forearm or the flat aspect of the back. Prick Test: 1 drop of extract concentrate applied to the unbroken skin of the forearm or the back followed by pricking the skin under the drop.

There are no absolute contraindications to the use of ragweed pollen extract in the diagnosis and treatment of ragweed allergy. When used in accordance with accepted principles of skin testing and immunotherapy, the extract is considered safe and effective. Relative contraindications include extreme sensitivity to the extract as demonstrated by previous anaphylaxis following skin testing or subcutaneous injection, recent myocardial infarction, and pregnancy. The benefit to risk ration must be evaluated in each of the above situations. Ragweed pollen extract should not be administered to persons who are not sensitive to ragweed pollen

Physicians who elect to administer ragweed pollen extract should be familiar with the clinical use of allergenic extracts and have the necessary emergency equipment and medication available to treat systemic allergic reactions. The injection of ragweed pollen extract may cause severe local and/ or systemic anaphylactic reactions in some individuals. To minimize this potential hazard, the relative sensitivity of the patient must be assessed from the allergic history and from clinical observations. Patients should be informed of this risk prior to skin testing and immunotherapy. The dosage must be reduced when starting a patient on fresh standardized (Antigen E) extract or when transferring a patient from non-standardized to standardized extract, even though the labeled strength of the old and new vials may be the same.

LOCAL REACTIONS. The occurrence of a hive 5 to 15 minutes after injection is usually due to leakage of extract into the skin along the needle tract. Firm pressure (not rubbing) at the site of injection immediately after withdrawal of the needle will usually prevent this reaction. It does not require a reduction in dosage. A strong local reaction with erythema and edema which persists at the injection site for several hours indicates that too much extract has been given. Failure to note this response may result in a serious generalized reaction. Treatment should be altered as follows: Additional injections should not be given until all evidence of the reaction has disappeared. The dosage should be reduced three levels, e.g., from 0.4 cc to 0.5 cc or the equivalent, and held at that level for two or three treatments.