DERMATOPHAGOIDES FARINAE Drug Interactions: What You Need to Know

INTERACTIONS

7.1 Beta Adrenergic Drugs Patients receiving beta blocker drugs may not be responsive to beta adrenergic drugs used to treat anaphylaxis 10 , and may wish to temporarily postpone treatment day of skin testing. All such decisions should be made in consultation with the physician <span class="opacity-50 text-xs">[see Warnings and Precautions (5.2)]</span>.

7.2 Antihistamines 1 Skin testing with allergenic extracts should not be performed within 2-3 days of first-generation H 1 -histamine receptor blockers (e.g., clemastine, diphenhydramine) and within 3 to 10 days of second-generation antihistamines (e.g., loratadine, terfenadine), except for astemizole, which requires an interval of 30-60 days between allergenic extract exposure and use. These products suppress histamine skin test reactions and could mask a positive response.

7.3 Topical Corticosteroids and Topical Anesthetics 1 Topical corticosteroids may suppress skin reactivity and should be discontinued at the skin test site for at least 2-3 weeks before skin testing. Topical local anesthetics may suppress flare responses and should be avoided at skin test sites.

7.4 Tricyclic Antidepressants 1 Tricyclic antidepressants can have potent antihistamine effects and will affect skin testing. Since use of tricyclics may alter skin test results, dosing for both skin testing and immunotherapy should be done with caution. If tricyclic medication has been recently discontinued, allow 7-14 days prior to skin testing to obviate the antihistamine effect. The risk of anaphylaxis in these patients should be carefully weighed against the risks and benefits of stopping tricyclics.

7.5 Other Drugs The suppressive action of other drugs should be considered and emphasizes the need for a histamine positive-control test. Patients who are receiving beta agonists may be unresponsive to the usual doses of epinephrine used to treat serious systemic reactions, including anaphylaxis (7.1) Patients should discontinue medications known to suppress the histamine response prior to skin testing including: antihistamines (7.2), tricyclics (7.4), and topical corticosteroids and topical anesthetics (7.3)

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.

AND PRECAUTIONS

5.1 Serious Systemic Reactions All concentrates of Greer Standardized Mite Extracts have the ability during skin testing and immunotherapy to elicit serious systemic reactions including anaphylactic shock and death <span class="opacity-50 text-xs">[see Adverse Reactions (6)]</span>. A review of the literature indicates that the incidence of near-fatal reactions to immunotherapy, defined as severe respiratory compromise, hypotension, or both, and requiring emergency treatment with epinephrine, has been estimated as 5.4 events per million injections in a 10-year retrospective survey of allergists. 3 Fatalities from immunotherapy injections have been estimated to occur at a rate of approximately one death per 2.0 to 2.8 million injections in 4-, 10- and 12-year retrospective surveys of allergists. 4-6 Because of the danger of serious reactions, caution is required in testing and treating high risk patients and those with medical conditions that reduce their ability to survive a serious systemic adverse event. High-risk patients are defined as those patients: with labile or steroid-dependent asthma, particularly in those suffering an exacerbation of their symptoms at the time of extract administration; with extreme sensitivity to a particular allergen(s); who are currently using beta blockers; who are receiving an accelerated immunotherapy build-up schedule (e.g., rush immunotherapy); who are being changed from one allergenic extract to another; who are receiving high doses of allergenic extracts. High risk patients have had fatal reactions. In addition, patients not high-risk but on beta blockers have had fatal reactions because beta blockers interfere with beta adrenergics such as epinephrine used in treatment or anaphylaxis. Patients should be kept under observation for a minimum of 30 minutes after receiving allergenic extracts so that any adverse reaction can be observed and properly handled. 2 Medications to treat systemic reactions, as well as emergency equipment should be available for immediate use. Extracts must only be administered by persons who are aware of the risk of systemic reactions, including anaphylaxis; are capable of handling such reactions; and have the necessary drugs and equipment on hand to do so.

5.2 Patients on Beta Blockers Patients receiving beta blockers may be unresponsive to the usual doses of epinephrine used to treat serious systemic reactions, including anaphylaxis. Inhalant allergy immunotherapy should be approached with caution in patients taking beta blockers. The risks of anaphylaxis in these patients should be carefully weighed against the benefits of immunotherapy <span class="opacity-50 text-xs">[see Drug Interactions (7.1)]</span>.

5.3 Autoimmune Disease Immunotherapy should be given cautiously to patients with other immunologic diseases and only if the risk from exposure to the allergen is greater than the risk of exacerbating the underlying disorder. 2 All concentrates of Greer Standardized Mite Extracts can cause serious systemic reactions of varying degrees of severity, including anaphylactic shock and death, particularly in patients: With labile or steroid-dependent asthma (5.1) With extreme sensitivity to allergen(s) (5.1) Who are currently using beta blockers (5.2) Who are on an accelerated immunotherapy build-up schedule (5.1) Who are being changed from one allergenic extract to another (5.1) Who are receiving high doses of allergen extracts (5.1)