Antigen Laboratories’ allergenic extracts are manufactured from source material listed on the vial label. Lower concentrations (e.g. 1:50, 1:33, etc.) may be prepared either by dilution from a more concentrated stock or by direct extraction. The extract is a sterile solution containing extractables of source materials obtained from biological collecting and/or processing firms and Antigen Laboratories. All source materials are inspected by Antigen Laboratories’ technical personnel in accordance with 21 CFR 680.1 (b) (1). The route of administration for immunotherapy is subcutaneous. The routes of administration for diagnostic purposes are intradermal or prick-puncture of the skin.
Food allergenic extracts may be manufactured on a weight/volume (w/v) or volume/volume (v/v) basis. Food extracts made from dried raw material are extracted at 2-10% (1:50-1:10 w/v ratio) in extracting fluid containing 50% glycerine. Slurries of juicy fruits or vegetables (prepared with a minimum amount of water for injection) are combined with an equal volume of glycerine for a ration of 1:1 volume/volume (v/v). Sodium chloride and sodium bicarbonate are added to the slurry and glycerine mixture. Fresh egg white extract is prepared by adding one part raw egg white to nine parts of extracting fluid (1:9 v/v).
Antigen E is considered the most important allergen of Short Ragweed pollen and is used for the standardization of Short Ragweed allergenic extracts. Stock mixtures containing Short Ragweed are analyzed for Antigen E content by radial immunodiffusion using Center for Biologics Evaluation and Research (CBER) references and anti-serum. Antigen E content expressed as units of Antigen E per milliliter (U/ml) is printed on container label.
Studies indicate allergic individuals produce immunoglobulins of the IgE class in response to exposure to allergens. Subsequent exposure to the allergen results in a combination of allergen with IgE antibody fixed on mast cells or basophil membranes. This cross-linking results in stimulation of mast cell which leads to release and generation of pharmacologically active substances that produce immediate hypersensitivity reaction.3
The mode of action of immunotherapy with allergenic extracts is still under investigation. Subcutaneous injections of increasing doses of allergenic extract into patients with allergic disease have been shown to result in both humoral and cellular changes including the production of allergen-specific IgG antibodies, the suppression of histamine release from target cells, decrease in circulating levels of antigen specific IgE antibody over long periods of time and suppression of peripheral blood T-lymphocyte cell responses to antigen.10, 14, 15
Allergenic extract is used for diagnostic testing and for the treatment (immunotherapy) of patients whose histories indicate that upon natural exposure to the allergen, they experience allergic symptoms. Confirmation is determined by skin testing. Diagnostic use of allergenic extracts usually begins with direct skin testing. This product is not intended for treatment of patients who do not manifest immediate hypersensitivity reactions to the allergenic extract following skin testing.
Do not administer in the presence of diseases characterized by bleeding diathesis. Individuals with autoimmune disease may be at risk of exacerbating symptoms of the underlying disease, possibly due to routine immunization. Patients who have experienced a recent myocardial infarction may not be tolerant of immunotherapy. Children with nephrotic syndrome probably should not receive injections due to immunization causing exacerbation of nephrotic disease.
Extreme caution is necessary when using diagnostic skin tests or injection treatment in highly sensitive patients who have experienced severe symptoms or anaphylaxis by natural exposure, or during previous skin testing or treatment. IN THESE CASES THE POTENCY FOR SKIN TESTS AND THE ESCALATION OF THE TREATMENT DOSE MUST BE ADJUSTED TO THE PATIENT’S SENSITIVITY AND TOLERANCE.
Injections should never be given intravenously. A 5/8 inch, 25 gauge needle on a sterile syringe allows deep subcutaneous injection. Withdraw plunger slightly after inserting needle to determine if a blood vessel has been entered.
Proper measurement of dose and caution in making injection will minimize reactions. Adverse reactions to allergenic extracts are usually apparent within 20-30 minutes following injection of immunotherapy.
Extract should be temporarily withheld or dosage reduced in case of any of the following conditions: 1) flu or other infection with fever; 2) exposure to excessive amounts of allergen prior to injection; 3) rhinitis and/or asthma exhibiting severe symptoms; 4) adverse reaction to previous injection until cause of reaction has been evaluated by physician supervising patient’s immunotherapy program.
Immunotherapy must be given under physician’s supervision. Sterile solutions, vials, syringes, etc. must be used. Aseptic technique must be observed in making dilutions from stock concentrates. The usual precautions in administering allergenic extracts are necessary, refer to boxed WARNINGS and “WARNINGS” section. Sterile syringe and needle must be used for each individual patient to prevent transmission of serum hepatitis, Human Immunodeficiency Virus (HIV) and other infectious agents.
Patient should remain under observation of a nurse, physician, or personnel trained in emergency measures for at least 20 minutes following immunotherapy injection. Patient must be instructed to report any adverse reactions that occur within 24 hours after injection. Possible adverse reactions include unusual swelling and/or tenderness at injection site, rhinorrhea, sneezing, coughing, wheezing, shortness of breath, nausea, dizziness, or faintness. Immediate medical attention must be sought for reactions that occur during or after leaving physician’s office.
Animal reproduction studies have not been conducted with allergenic extracts. It is not known whether allergenic extracts cause fetal harm during pregnancy or affect reproductive capacity. A systemic reaction to allergenic extract could cause uterine contractions leading to spontaneous abortion or premature labor. Allergenic extracts should be used during pregnancy only if potential benefit justifies potential risk to fetus.11
It is not known whether allergenic extracts are excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when allergenic extracts are administered to a nursing woman.
Allergenic extracts have been used routinely in children, and no special safety problems or specific hazards have been found. Children can receive the same dose as adults. Discomfort is minimized by dividing the dose in half and administering injection at two different sites.16, 17
Antihistamines. Antihistamines inhibit the wheal and flare reaction. The inhibitory effect of conventional antihistamines varies from 1 day up to 10 days, according to the drug and patient’s sensitivity. Long acting antihistamines (e.g., astemizole) may inhibit the wheal and flare for up to forty days.1, 2
Imipramines, phenothiazines, and tranquilizers. Tricyclic antidepressants exert a potent and sustained decrease of skin reactions to histamine. This effect may last for a few weeks. Tranquilizers and antiemetic agents of the phenothiazine class have H1 antihistaminic activity and can block skin tests.1
Corticosteroids. Short-term (less than 1 week) administration of corticosteroids at the therapeutic doses used in asthmatic patients does not modify the cutaneous reactivity to histamine, compound 48/80, or allergen. Long-term corticosteroid therapy modifies the skin texture and makes the interpretation of immediate skin tests more difficult.1
Beta-Blockers. Patients receiving beta-blockers may not be responsive to epinephrine or inhaled bronchodilators. The following are commonly prescribed beta-blockers: Levatol, Lopressor, Propanolol Intersol, Propanolol HCL, Blocadren, Propanolol, Inderal-LA, Visken, Corgard, Ipran, Tenormin, Timoptic. Ophthalmic beta-blockers: Betaxolol, Levobunolol, Timolol, Timoptic. Chemicals that are beta-blockers and may be components of other drugs: Acebutolol, Atenolol, Esmolol, Metoprolol, Nadolol, Penbutolol, Pindolol, Propanolol, Timolol, Labetalol, Carteolol.1
Beta-adrenergic agents. Inhaled beta2 agonists in the usual doses used for the treatment of asthma do not usually inhibit allergen-induced skin tests. However, oral terbutaline and parenteral ephedrine were shown to decrease the allergen-induced wheal.1
Specific Immunotherapy. A decreased skin test reactivity has been observed in patients undergoing specific immunotherapy with pollen extracts, grass pollen allergoids, mites, hymenoptera venoms, or in professional beekeepers who are spontaneously desensitized. Finally, it was shown that specific immunotherapy in patients treated with ragweed pollen extract induced a decreased late-phase reaction.1
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