[Drug hypersensitivity in patients with presumed histamine intolerance and mast cell activation disease]

Drug hypersensitivity in patients with presumed histamine intolerance and mast cell activation disease Abstract. There is no evidence to suggest that sensitization against drugs occurs more frequently among patients with presumed histamine intolerance compared to patients with normal tolerance to histamine. However, preclinical data suggest interactions between some drugs and histamine catabolism. Nevertheless, the clinical relevance of these findings remains unclear as histamine in humans can be catabolized by different pathways. There are no drugs for which induction or worsening of histamine intolerance has been established clinically. In patients with mastocytosis an increased rate of sensitization and specific allergies to drugs is unlikely. However, pathophysiologic understanding suggests that mast cell activation disease might enhance drug reactions, which are induced by mast cell degranulation. Additionally a possible lower threshold for unspecific mast cell degranulation in patients with mastocytosis could lead to pseudoallergic drug reactions. However an increase in the number of drug substances triggering such reactions is not expected. Nevertheless, there are lists of drug substances which are assumed to cause anaphylactic / anaphylactoid reactions especially in patients with mastocytosis. Conversely, these lists are rarely based on clinical evidence. A recently published prospective trial did not find any relevant increase of acetyl salicylic acid hypersensitivity in patients with mastocytosis. Patients with mastocytosis and a history of drug hypersensitivity should be thoroughly assessed by an allergological workup and advised to avoid triggering and / or cross reactive drug substances. We recommend that these patients avoid drugs which may interfere with the treatment of anaphylaxis like beta blockers, certain antidepressants or Catechol-O-methyltransferase inhibitors because of the increased risk for enhanced hypersensitivity reactions.