Epinephrine 1:1000 should be available as well as personnel trained in administering emergency treatment. Allergenic Extracts are not intended for intravenous injections. For safe and effective use of allergen extracts, sterile diluent, sterile vials, sterile syringes should be used and aseptic precautions observed when making a dilution and/or administering the allergen extract injection. A sterile tuberculin syringe graduated in 0.1 mL units to measure each dose for the prescribed dilution should be used. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
To reduce the risk of an occurrence of adverse reactions, begin with a careful personal history plus a physical exam. Confirm your findings with scratch or intradermal skin testing. Patients should be observed for 30 minutes after any test.
Information for Patients: All concentrates of allergen extracts including standardized pollen extracts, have the potential to cause serious local and systemic reactions including death, in sensitive patients. To minimize this potential hazard, the relative sensitivity of the patient must be assessed from an allergic history and from clinical observations. In certain individuals, life-threatening reactions may occur. Patients should be informed of this risk prior to skin testing and immunotherapy. Patients should be instructed to recognize adverse reaction symptoms that may occur and to report all adverse reactions to a physician. Patients should be told to wait in the office after injections for at least 30 minutes.
Drug Interaction: Antihistamines and Hydroxyzine can significantly inhibit the immediate skin test reactions as they tend to neutralize or antagonize the action of histamine (14). This effect has been primarily documented when testing was performed within 1 to 2 hours after drug ingestion. Although partial inhibition of the skin test reaction had been observed for longer periods, it was minor. Epinephrine injection inhibits the immediate skin test reactions for several hours. Patients on delayed absorption antihistamine tablets should be free of such medication for 48 hours before testing. Patients using Astemizole (Hismanal) may experience prolonged suppression and should be free from such medication for up to 6 to 8 weeks prior to testing. Refer to package insert from applicable long acting antihistamine manufacturers for additional information. In the event of a serious adverse reaction, patients receiving beta-blockers may not be responsive to epinephrine or inhaled bronchodilators.
Pregnancy: Category C. Animal reproduction studies have not been conducted with D. farinae or D. pteronyssinus mite extracts, it is not known whether this extract can incur fetal harm when administered to a pregnant women or can effect reproduction capacity. Standardized D.farinae or D.pteronyssinus Mite extract should be given to pregnant women and nursing mothers only if clearly needed.
Nursing Mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Allergenic Extract, Standardized Mites, is administered to a nursing woman. There are no current studies on secretion of the extract components in human milk, or their effect on the nursing infant.
Pediatric Use: Children have been used extensively as patients in studies with mite extracts. However, it is recommended that children be treated only when indicated (6,7,8). Allergenic extracts have been tested in children over two years of age (9). (See WARNINGS and ADVERSE REACTIONS).
Anaphylaxis and other systemic reactions may occur such as induced asthma, itching of nose and throat, breathlessness, urticaria and local reactions. Local reactions can be defined as an area of large erythema, swelling or pruritus at the injection site. Further indications of adverse reactions are edema, wheezing, dyspnea, locomotive impairment, marked perspiration, coughing, hypertension, shock and upper airway obstruction.
Adverse systemic reactions usually occur within minutes and consist primarily of allergic symptoms such as generalized skin erythema, urticaria, pruritus, angioedema, rhinitis, wheezing, laryngeal edema and hypotension. Less commonly, nausea, emesis, abdominal cramps, diarrhea and uterine contractions may occur. Severe reactions may cause shock and loss of consciousness. Fatalities have occurred rarely. These systemic reactions occur with varying frequency in different clinics. To some extent, the reaction rate is related to the type and dose of administered extract and to the degree of sensitivity of the patient. Despite all precautions, occasional reactions are unavoidable.
Reports from regulatory authorities in Sweden to the Center for Biologics Evaluation and Research (CBER) indicated that several deaths have been associated with the use of mite extracts. The CBER was subsequently informed that these deaths may have been related to use by physicians or other health professionals untrained in the administration of potent allergens rather than a product defect. It should be noted that anaphylaxis and deaths following the injection of mite extracts have also been reported by the British Committee on Safety in Medicine in the British Medical Journal, V293,pp948,1986.
Local reactions consisting of erythema, itching, swelling tenderness and sometimes pain may occur at the injection site. These reactions may appear within a few minutes to hours and persist for several days. Local cold applications and oral antihistamines may be effective treatment. For marked and prolonged local reactions steroids may be helpful.
The treatment of systemic allergic reactions is dependent upon the symptom complex. In cases of an occurrence of a systemic or anaphylactic reaction, apply a tourniquet above the site of injection and inject intramuscularly or subcutaneously 0.3 to 0.5mL of 1:1000 Epinephrine Hydrochloride into the opposite arm. The dose may be repeated in 5-10 minutes if necessary. Loosen the tourniquet at least every 10 minutes. The Epinephrine Hydrochloride 1:1000 dose for infants to 2 years is 0.05 to 0.1 mL: for children 2 to 6 years it is 0.15 mL:, for children 6-12 years it is 0.2 mL.
Patients unresponsive to Epinephrine may be treated with Theophylline. Studies on asthmatic subjects reveal that plasma concentrations of Theophylline of 5 to 20 µg/mL are associated with therapeutic effects. Toxicity is particularly apparent at concentrations greater than 20 µg/mL. A loading dose of Aminophylline of 5.8 mg/kg intravenously followed by 0.9 mg/kg per hour results in plasma concentrations of approximately 10 µg/mL. (Mitenko and Ogilive, Nicholoson and Chick,1973)
Other beta-adrenergic drugs such as Isoproterenol, Isoetharine, or Albuterol may be used by inhalation. The usual dose to relieve broncho-constriction in asthma is 0.5 mL or the 0.5% solution for Isoproterenol HCl. The Albuterol inhaler delivers approximately 90 mcg of Albuterol from the mouthpiece. The usual dosage for adults and children would be two inhalations repeated every 4-6 hours. Isoetharine supplied in the Bronkometer unit delivers approximately 340 mcg Isoetharine. The average dose is one to two inhalations.
Respiratory obstruction not responding to parenteral or inhaled bronchodilators may require Theophylline, oxygen, intubation and the use of life support systems. Parenteral fluid and/or plasma expanders may be utilized for treatment of shock. Adrenocorticosteroids may be administered parenterally or intravenously.
Antihistamines may offer relief of recurrent urticaria, associated skin reactions and gastrointestinal symptoms. Persistent wheezing may necessitate intravenous aminophylline treatment. For profound shock and hypotension, intravenous fluids, vasopressor and oxygen may also be needed. Maintenance of a patent airway is critical if upper and lower airway obstruction is present. Corticosteroids may provide benefit if symptoms are prolonged or recurrent.
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