Drug Interaction Report

MONITOR: Monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), catechol-O-methyltransferase (COMT) inhibitors, thyroid hormone, antihistamines, cardiac glycosides (e.g. digoxin) and diuretics may potentiate the response to epinephrine, including fatal consequences, in the treatment of serious systemic reactions that may occur during immunotherapy with allergenic extracts. Vasoconstricting and hypertensive effects may be potentiated by MAOIs, tricyclic antidepressants, and COMT inhibitors. Arrhythmogenic effects may be potentiated by thyroid hormones, antihistamines, cardiac glycosides and diuretics.

MANAGEMENT: Immunotherapy with allergenic extracts may not be appropriate in patients receiving MAOIs, tricyclic antidepressants, COMT inhibitors, thyroid hormone, antihistamines and cardiac glycosides as these patients may experience an exaggerated response to the usual doses of epinephrine required to reverse a systemic reaction.

ADJUST DOSING INTERVAL: Since sublingual preparations of allergenic extracts are meant to be absorbed directly from tissues under the tongue into the blood stream, consuming food or beverage during or immediately after administration may reduce the systemic bioavailability of the medication.

MONITOR: Coadministration of allergenic extracts for allergy immunotherapy with alcohol may potentiate the risk of allergic reactions, including anaphylaxis. According to some studies, alcohol is an augmenting factor influencing immunological mechanisms that can induce more severe allergic reactions and is involved in up to 15% of cases of anaphylactic reactions. Proposed mechanisms include an increase in allergen absorption from altered permeability of the intestinal epithelial barrier, enhancing mast cell and basophil activation, and an increase in serum IgE concentrations. A causal relationship with all allergenic extracts has not been established.

MANAGEMENT: Food or beverage should not be taken with, or for at least 5 minutes after, the administration of sublingual allergenic extracts. Patients should also avoid swallowing for about 1 minute following placement of the allergen extract under the tongue. Caution is advised if allergenic extracts for immunotherapy are used concomitantly with alcohol. Some manufacturers of peanut allergen extract recommend alcohol not be consumed for 2 hours before, or 2 hours after taking peanut allergen extract and if alcohol use cannot be avoided, that withholding or decreasing peanut allergen dosage should be considered. Individual prescribing information should be consulted for further guidance and clinical monitoring may be considered.