Short Ragweed
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Questions & Answers
Side Effects & Adverse Reactions
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 (see adverse reactions).
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. This is necessary due to a loss of extract potency during storage in the physician's office. The antigen E content of old and new extract must be compared and adjusted by dosage reduction and/or dilution before new extract is administered. The amount of new extract given from the old vial, assuming both extracts contain comparable amounts of antigen E. Any evidence of a local or generalized reaction requires a reduction in dosage during the initial stages of hyposensitization as well as during maintenance therapy.
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Manufacturer Warnings
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FDA Labeling Changes
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Uses
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 (9, 10, 11), 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. Immunologic changes resulting from treatment with short ragweed pollen extract are believed to include:
- The induction of specific anti-ragweed IgG antibodies commonly referred to as "blocking antibodies" 12, 13.
- A decrease in the elevation of ragweed specific IgE during and immediately following the ragweed pollen season 14.
- A reduction of circulating anti-ragweed IgE after long-term immunotherapy 15.
- A decrease in skin reactivity to the extract 16 and a decrease in leukocyte sensitivity to histamine release 17 after long-term immunotherapy.
History
There is currently no drug history available for this drug.
Other Information
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:
- In vitro studies with antigen E have shown that it is capable of causing histamine release from peripheral leukocytes of ragweed sensitive persons 1.
- 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.
- 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.
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 should be kept at 2°C to 8°C during use and office storage to retain potency. Higher temperatures have an adverse affect on antigen E.
Sources
Short Ragweed Manufacturers
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Allermed Laboratories, Inc.
![Short Ragweed (Ambrosia Artemisiifolia) Injection [Allermed Laboratories, Inc.]](/wp-content/themes/bootstrap/assets/img/loading2.gif)
Short Ragweed | Allermed Laboratories, Inc.
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.
AgE Units
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.
Intradermal Test: 0.05 ml of extract containing 0.25 antigen E units per ml given intradermally on the volar surface of the forearm or outer aspect of the upper arm. This test should not be performed unless the patient is negative to a properly administered and interpreted scratch or prick test. A final intradermal test using 0.05 ml of extract containing 2.5 antigen E units per ml may be used to rule out skin sensitivity to ragweed allergen.
INTERPRETATION OF RESULTS
Scratch and Prick Test
A negative test shows only a slight red area at the site of scarification or prick penetration. Positive tests are scored as follows:
1+ Erythema with 5 mm wheal
2+ Erythema with 5 - 10 mm wheal
3+ Erythema with a 10 - 15 mm wheal
4+ Erythema with a wheal 15 mm (or larger) with pseudopodia
Intradermal Test
A negative test shows no change in the appearance and size of the 5 mm wheal created by the I.D. injection of 0.05 ml of extract. Positive tests are scored as follows:
1+ Erythema with 10-20 mm with a 5-10 mm wheal
2+ Erythema with 20-30 mm with a 5-10 mm wheal
3+ Erythema with 30-40 mm with a 10-15 mm wheal
4+ Erythema greater than 40 mm with a 15 mm wheal (or larger) with pseudopodia
IMMUNOTHERAPY
Concentrated ragweed extract must be diluted before administration to new patients. As a rule, extract containing 0.01 to 0.05 units of antigen E per ml are safe to initiate immunotherapy. An intradermal skin test with the intended starting dose may be done as an additional precaution in evaluating the patient's sensitivity.
Injections should be given subcutaneously in the outer aspect of the upper arm. Care must be taken to avoid injecting the extract into a blood vessel, because of the potential hazard of anaphylaxis. Concentrated extract is usually administered once every two to four weeks at a maximum dose of 0.2 ml. A mild burning sensation immediately following the injection of concentrated extract is due to the glycerol in the extract. It should not be interpreted as an adverse allergic response. A suggested dosage schedule is shown in the Table below.
Patients who have received allergenic extract for maintenance therapy should not be given the same dose from a fresh vial of extract. The antigen E content of ragweed pollen extract varies from lot to lot. Although the potency of fresh extract can be compared with that of previously administered product and adjusted accordingly, it is advisable to reduce the dosage of fresh extract to one-half the amount give from a previous lot. The antigen E content of ragweed pollen extract diminishes during storage and use in the physician's office, and, therefore, may be less than that specified on the vial label. In addition, ragweed pollen extract contains other components which may contribute to the overall allergenicity of the product 18.
SUGGESTED DOSAGE SCHEDULE FOR RAGWEED EXTRACT BASED ON ANTIGEN E CONCENTRATION (units per ml)
Concentrated extracts (w/v 1:20) of short ragweed pollen usually contain between 100 and 300 units antigen E per ml. Mixed short-giant ragweed pollen extracts contain approximately one-half these values.
0.01/ml
frequency
twice
weekly AgE Units
0.1/ml
frequency
twice
weekly AgE Units
1.0/ml
frequency
twice
weekly
AgE Units
10/ml
frequency
twice
weekly AgE Units
100/ml
frequency
twice
weekly No. ml No. ml No. ml No. ml No. ml 1 0.025 1 0.025 1 0.025 1 0.025 1 0.025 2 0.05 2 0.05 2 0.05 2 0.05 2 0.05 3 0.10 3 0.10 3 0.10 3 0.10 3 0.10 4 0.15 4 0.15 4 0.15 4 0.15 4 0.15 5 0.20 5 0.20 5 0.20 5 0.20 5 0.20 6 0.25 6 0.25 6 0.25 6 0.25 6 0.25 7 0.30 7 0.30 7 0.30 7 0.30 7 0.30Note: Do not exceed a dose of 0.2 ml if the extract being administered contains 50% glycerol by volume
Studies 10, 11 have shown that the accumulated pre-seasonal dose of short ragweed pollen extract should be in the range of 250 to 1000 units of antigen E to effectively reduce ragweed-related symptoms 3, 19. This dosage of antigen E is contained in 2.5 ml to 10.0 ml of extract containing 100 antigen E units/ml. Treatment with a maximum tolerated dose is recommended for both short ragweed pollen extract and mixed short-giant ragweed extract.
The maintenance dose of ragweed pollen extract is defined as the highest tolerated dose that is consistently well tolerated without undue pain or swelling and which provides maximum relief to symptoms. The interval between maintenance injections should not exceed 4 weeks, since tolerance to the extract may be lost at longer intervals. If the interval exceeds 4 weeks, the dosage should be reduced by one-half for every additional two week period. A reduction in the maintenance dose also may be necessary during the ragweed season, due to the overdosing effects of inhaled allergen combined with injected allergen. As a rule, it is advisable to reduce the dosage by one-half during ragweed pollination and to increase the frequency of injections as needed to provide adequate relief symptoms. The dosage of ragweed pollen extract given to children is the same as the adult dose except for slight modifications due to body size and weight. A child's dose of 0.2 ml is considered comparable to an adult dose of 0.5 ml of the same dilution. Maintenance injection should be continued for a period of two to three years or longer, depending upon patient tolerance and clinical response.
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