House Dust Mite, Dermatophagoides Farinae

FDA Drug Information • Also known as: House Dust Mite, Dermatophagoides Farinae

Brand Names: House Dust Mite, Dermatophagoides Farinae
Drug Class: Standardized Insect Allergenic Extract [EPC]
Route: CUTANEOUS, INTRADERMAL, SUBCUTANEOUS
Dosage Form: INJECTION
Product Type: HUMAN PRESCRIPTION DRUG

⚠ Boxed Warning (Black Box)

WARNINGS This product is intended for use by physicians who are experienced in the administration of allergenic 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, especially steroid dependent/liable asthmatics, these reactions maybe life-threatening or cause death (11). 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. Serious adverse reactions to this product should be reported to MEDWATCH, Food and Drug Administration, 5600 Fishers Lane, MD 20852-9787. Telephone 1-800-822-7967 or www.vaers.hhs.gov.

Description

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).

What Is House Dust Mite, Dermatophagoides Farinae Used For?

INDICATIONS AND USAGE 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).

Dosage and Administration

DOSAGE AND ADMINISTRATION Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. The product should be discarded if discoloration or particles are observed. DIAGNOSTIC USE: Percutaneous Tests : The skin test concentration of 10,000 AU/mL in dropper vials is used for scratch or prick-puncture testing. Puncture tests performed with D. farinae extract on 5 persons sensitive to mite showed a mean diameter wheal of 8.8 mm ± 1.8 mm and mean diameter erythema of 39.2 mm ± 5.3 mm. Puncture tests with D. pteronyssinus extract on 10 persons sensitive to mite showed a mean diameter wheal of 7.8 mm ± 4.1 mm and mean erythema of 33.7 mm ± 12.0 mm. Intradermal Tests : Extract for intradermal testing should be prepared by diluting the 10,000 AU/mL stock concentrate in bulk vials with sterile saline with or without human serum albumin. Intradermal skin tests (0.05 mL) in persons highly sensitive to mite showed the following results: Table 1 AU/mL to elicit 50 mm sum of diameter erythema reaction Allergen No. of Persons Mean Range D. farinae 5 0.0040 0.0013-0.0124 D. pteronyssinus 10 0.0031 0.0001-0.1416 Intradermal tests should only be performed after a scratch or prick-puncture test has been administered with a negative result. Patients who do not react to a valid scratch or prick-puncture test should be tested intradermally with 0.02 to 0.05 mL of a 10 AU/mL (1:1,000 v/v of the 10,000 AU/mL concentrate). If this test is negative, a second intradermal test may be performed using a 100 AU/mL (1:100 v/v dilution of 10,000 AU/mL concentrate). Skin tests are graded in terms of the wheal and erythema response noted at 15 to 20 minutes. Wheal and erythema size may be recorded by actual measurement of the extent of both responses. THERAPEUTIC USE: The dosage of mite extract administered by subcutaneous injection is highly individualized and varies according to the degree of sensitivity of the patient, his clinical response and tolerance to the extract administered during the early phases of an injection regimen. In patients who appear to be highly sensitive by history and skin test, the initial dose of the extract should be 0.05 mL of a 0.1 AU/mL dilution or as established by skin test titration. The amount of allergenic extract is increased at each injection by not more than 50% - 100% of the previous amount, and the next increment is governed by the response to the last injection. Large local reactions which persist for longer than 24 hours are generally considered an indication for repeating the previous dose or reducing the dose. Any evidence of systemic reaction is an indication for a significant reduction (at least 50%) in the subsequent dose. The upper limits of dosage have not been established; however, doses larger than 0.2 mL of the concentrate may be painful due to the glycerin content of the extract. The optimal interval between doses of mite extract...

Side Effects (Adverse Reactions)

ADVERSE REACTIONS 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 (11). 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. 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 and other extracts also have been reported by the British Committee on Safety in Medicine in the British Medical Journal, 293:943, 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 somewhat dependent upon the symptom complex. Epinephrine hydrochloride 1:1,000 aqueous, in an adult dose of 0.3 - 0.5 mL (or 0.01 mL per kg. for children) administeredsubcutaneously in the opposite arm is the immediate treatment of choice. A tourniquet should be placed above the site of the extract injection if the injection was done on the extremities. 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, vasopressors and oxygen also may be needed. Maintenance of an open airway is critical if upper airway obstruction is present. Corticosteroids may provide benefit if symptoms are prolonged or recurrent.

Warnings and Precautions

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.

Contraindications

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.

Overdosage

OVERDOSAGE A strong local reaction to the injection of extract may be treated with oral antihistamines and the local application of a cold compress. The dosage must be reduced and additional extract must not be given until all evidence of the reaction has disappeared. A systemic reaction following the injection of extract must be treated immediately with Epinephrine hydrochloride 1:1,000 aqueous (see Adverse Reactions, paragraph 4 above).

How Supplied

HOW SUPPLIED Extract of D. farinae and D. pteronyssinus containing 5,000 and 10,000 Allergy Units per mL is supplied in 50% glycerol v/v in 10 mL, 30 mL and 50 mL vials. Extract containing 10,000 Allergy Units per mL is supplied in 50% glycerol v/v in dropper vials for scratch or prick-puncture testing. An equal v/v mixture of the two mites is offered in 10, 30 and 50 mL vial sizes at a concentration of 2,500 AU/mL or 5,000 AU/mL for each mite. See DESCRIPTION above for the complete list of the active and inactive ingredients of this product. Extract of D. farinae and D. pteronyssinus may be diluted in sterile buffered saline containing 0.4% phenol or in sterile buffered saline containing human serum albumin and 0.4% phenol. STORAGE AND HANDLING Extract should be stored at 2-8°C since higher temperatures may adversely affect stability. Do not freeze.

About This Information

This drug information is sourced from FDA-approved labeling via the openFDA database. It is intended for educational and reference purposes only. This is not medical advice. Always consult your healthcare provider before making decisions about medication. Drug information may be updated by the FDA; check with your pharmacist for the most current information.

What are side effects?

Side effects are unwanted reactions that can occur when taking a medication. They range from mild (headache, nausea) to severe (allergic reactions, organ damage). Not everyone experiences side effects, and severity varies. Report any concerning side effects to your doctor.

What are drug interactions?

Drug interactions occur when a medication is affected by another drug, food, or supplement. Interactions can make medications less effective or cause dangerous side effects. Always tell your doctor about all medications and supplements you take.