House Dust Mite, Dermatophagoides Farinae

HOUSE DUST MITE, DERMATOPHAGOIDES FARINAE- dermatophagoides farinae injection
HOUSE DUST MITE, DERMATOPHAGOIDES PTERONYSSINUS- dermatophagoides pteronyssinus injection
Allermed Laboratories, Inc.

WARNINGS

This product is intended for use by physicians who are experienced in the administration of allergens extracts or for use under the guidance of an allergy specialist. The initial dose must be based on skin testing as described in the dosage and administration section of this insert. Patients being switched from alum-absorbed or other types of precipitated extracts or non-standardized extracts to this extract should be started as though they were coming under treatment for the first time. Patients should be instructed to recognize adverse reaction symptoms and cautioned to contact the physician’s office if symptoms occur. As with all allergenic extracts, severe systemic reactions may occur and in certain individuals these reactions may be life-threatening or cause death. Patients should be observed for at least 20 minutes following treatment. Emergency measures as well as personnel trained in their use should be immediately available in the event of a life-threatening reaction. Patients being switched from one lot of extract to another from the same manufacturer should have the dose reduced to 25 percent. Patients receiving beta-blocking drugs may be refractive to the usual dose of epinephrine, in the event that epinephrine is required to control an adverse allergic reaction to this product. This product should never be injected intravenously. See also the WARNINGS, and ADVERSE REACTIONS Sections below.

DESCRIPTION

Mite extract is a sterile solution containing the extractables of mite whole bodies in 0.25% sodium chloride, 0.125% sodium bicarbonate, 50% glycerol by volume and 0.4% phenol as a preservative. The mites are grown on a medium of yeast and pork and are handled and cleaned in a manner to remove more than 99% of the food medium. The medium contains no material of human origin.

This extract may be administered by the scratch, prick-puncture, or intradermal methods of skin testing for diagnostic purposes and subcutaneously for therapeutic purposes as directed under Dosage and Administration.

Intradermal skin tests in patients who were puncture test positive (Sum E ≥ 40 mm) to either D. farinae or D. pteronyssinus extract were performed with extracts of the mite food medium obtained from the same supplier. The results, submitted to the FDA by several manufacturers, were as follows: By intradermal testing, there was 1 positive (Sum E ≥ 20 mm) in 44 individuals at an estimated 1% level of medium content (approximately the same as contained in the mite extract). At a ten-fold increase (estimated 10% medium content), 4 positives in 40 individuals were observed. Two of the individuals who were skin test positive to the mite extract and who also were skin test positive to the medium extract were also skin test positive to an extract of yeast ( Saccharomyces sp.) when tested by the puncture method.

The extract is standardized by comparing its relative potency by ELISA competition to a U.S. reference mite extract available from the Center for Biologics Evaluation and Research, U.S. Food and Drug Administration. The U.S. reference extract has been assigned a potency of 10,000 AU/mL based on quantitative skin testing 1.

CLINICAL PHARMACOLOGY

The mechanism for the pharmacologic action of allergenic extracts used diagnostically is based on the liberation of histamine and other substances when the allergen reacts with IgE antibody attached to mast cells. The mechanism of the therapeutic effect is not well understood and further research is required to substantiate current hypotheses.

Mites belonging to the genus Dermatophagoides are found in approximately 80% of house dust samples throughout the world 2,3. D. farinae is common in much of the United States 3 , although D. pteronyssinus is predominant in certain coastal regions and both species are commonly found in homes 4,5.

The diagnosis of mite allergy is established by the allergy history and skin test reactivity 6,7. Immunotherapy with mite extract has been studied by several investigators. It is generally believed that hyposensitization with this product is helpful in reducing symptoms associated with house dust allergy 8,9.

INDICATIONS AND USEAGE

Standardized mite extract is indicated for use in the diagnosis of patients with a history of allergy to mites or house dust and for the treatment of patients with a history of mite allergy who have established sensitivity to mites by diagnostic skin testing.
The use of mite extract for the above purposes should be made only by physicians with special familiarity and knowledge of allergy as described in a standard allergy textbook 10.

CONTRAINDICATIONS

Injections of mite extract should not be administered in the presence of diseases characterized by a bleeding diathesis. Immunotherapy should not be started in patients until a specific diagnosis of Type I allergy to mite is made by a physician based on skin testing with this product.
Other contraindications include:

EXTREME SENSITIVITY TO MITE: Determined from previous anaphylaxis following skin testing, immunotherapy, or natural exposure.
AUTOIMMUNE DISEASE: Individuals with autoimmune disease maybe at risk, due to the possibility of routine immunizations exacerbating symptoms of the underlying disease.
MYOCARDIAL INFARCTION: Patients who have experienced a recent myocardial infarction may not be able to tolerate immunotherapy. The benefit-to-risk ratio must be carefully evaluated.
CHILDREN WITH NEPHROTIC SYNDROME: Children with nephrotic syndrome require careful consideration and probably should not receive immunotherapy due to a variety of seemingly unrelated events that may cause an exacerbation of nephrotic disease.

WARNINGS

Concentrated extract must be diluted with sterile diluent prior to first use on a patient for treatment or intradermal testing. All concentrates of allergenic extract are manufactured to assure high potency and therefore have the ability to cause serious local and systemic reactions, including death in sensitive patients 11. Patients should be informed of this risk and precautions should be discussed prior to initiating immunotherapy (see PRECAUTIONS below).
Allergenic extract should be temporarily withheld from patients or the dose adjusted downward if any of the following conditions exist: 1) severe symptoms of rhinitis and/or asthma; 2) infection or flu accompanied by fever; 3) exposure to excessive amounts of clinically relevant allergen prior to a scheduled injection.
The dosage must be reduced when starting a patient on fresh standardized mite extract or when transferring a patient from non-standardized or modified extract 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 mite allergen content of old and new extract may be compared and adjusted by dosage reduction and/or dilution before the new extract is administered. The amount of new extract given should not exceed 25% of the last dose given from the old vial, assuming both extracts contain comparable amounts of mite allergen. Any evidence of a local or generalized reaction requires a reduction in dosage during the initial stages of immunotherapy, as well as during maintenance therapy.
Beta-blocking drugs may make patients refractory to the usual dose of epinephrine, in the event epinephrine is required to treat an adverse allergic reaction.

PRECAUTIONS

GENERAL: This product should not be injected intravenously. The risk of severe allergic reactions can be minimized by taking a careful history and by the use of scratch or prick-puncture testing prior to intradermal testing. If the scratch or prick-puncture test is negative, an intradermal test with a one hundred-fold dilution of the concentration used for scratch or prick tests usually is safe. If there is a history of unusual sensitivity or if the scratch or prick-puncture test is not performed first, a more dilute solution such as 1:10,000 v/v of the concentrate should be used initially for intradermal testing.
Systemic allergic reactions may occur as a result of immunotherapy. The risk can be minimized by adherence to a careful injection schedule, which starts with a low concentration of extract and is increased slowly. The physician must be prepared to treat anaphylaxis should it occur and have the necessary drugs and equipment on hand to do so. Extracts should not be administered by the patient or other individuals who are not prepared to treat anaphylaxis should it occur.
A separate sterile tuberculin syringe graduated in 0.01 mL should be used for each injection.
Antihistamines and hydroxyzine can significantly inhibit the immediate skin test reaction (see DRUG INTERACTION).

INFORMATION FOR PATIENTS: Because most serious reactions following the administration of allergenic extracts occur within 20 minutes of the injection, the patient should remain under observation for this period of time. The size of the local reaction should be recorded, because increasingly large local reactions may precede a subsequent systemic reaction with increasing dosage. The patient should be instructed to report any unusual reactions to the attention of the physician. In particular, this includes swelling and/or tenderness at the injection site or reactions such as rhinorrhea, sneezing, coughing, wheezing, shortness of breath, nausea, dizziness or faintness.
Caution should be exercised in testing or treating pregnant females because a systemic reaction might conceivably cause uterine muscle contractions leading to abortion.

CARCINOGENESIS, MUTAGENESIS, IMPAIRMENT OF FERTILITY: Long term studies in animals have not been conducted with allergenic extracts to determine their potential for carcinogenicity, mutagenicity or impairment of fertility.

PREGNANCY CATEGORY C: Animal reproduction studies have not been conducted with mite extract. It is also not known whether mite extract can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Mite extract should be given to a pregnant woman only if clearly needed.

PEDIATRIC USE: Although standardized mite extract has not been studied in children, unstandardized extract of D. farinae has been administered by the prick test to asthmatic children ages 1 to 16 without any reported adverse response 6. Extract of D. pteronyssinus has been given subcutaneously for hyposensitization to children ages 5 to 14 with adverse reactions being limited to local discomfort, redness and swelling for one or two, days 7.

NURSING MOTHERS: 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.

DRUG INTERACTION: Antihistamines and hydroxyzine can inhibit the immediate skin test reaction. Patients being treated with delayed absorption antihistamine tablets should be free of such medication for 48 hours before testing. Non-sedating antihistamines, such as terfinadine and astemizole, may variable suppress the skin response for longer periods of time. Epinephrine injection inhibits the immediate skin test reaction for several hours.
Beta-blocking drugs may make patients refractory to the usual dose of epinephrine, in the event epinephrine is required to treat an adverse allergic reaction.

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