title: Sympathomimetic drug allergy: cross-reactivity study by patch test.
abstract: BACKGROUND
  Sympathomimetic (alpha-adrenergic) drugs are mainly used because of their vasoconstrictor properties, for nasal congestion, or as mydriatics. Although sympathomimetic drugs are used often, allergic reactions are rare, especially when the drugs are administered systemically. Cross-reactivity may exist among catecholamine derivatives, although reported data on this are contradictory. In this study, we investigate if there is cross-reactivity in patch tests among these drugs.
  
  
  METHODS
  Patch tests with 10% phenylephrine and 10% pseudoephedrine in petrolatum, and 10% and 20% ephedrine, 10% phenylpropanolamine, 5% fepradinol, 1% methoxamine, and 10% oxymetazoline, all administered in dimethyl sulfoxide (DMSO), were carried out in 14 patients with a history of allergy to any of these drugs. DMSO was used as the negative control.
  
  
  RESULTS
  All patients except one (patient number five) showed positive patch-test reactions to at least two different drugs. Nine patients (64.3%) were cross-sensitized to three or more different drugs, and 57.1% of patients were sensitized to four or more sympathomimetic drugs. Patients who experienced generalized rashes caused by orally administered pseudoephedrine had a stronger response and more cross-reactivity with other sympathomimetic drugs in patch tests than those who experienced local contact dermatitis.
  
  
  CONCLUSIONS
  We conclude that there is cross-reactivity among the different sympathomimetic drugs tested, especially if the drug is administered systemically.
authors.affiliation: Allergy Unit, Hospital General Universitario Gregorio Marañón, Madrid, Spain. ruthbj@teleline.es
authors.forename: Ruth
authors.initials: R
authors.lastname: Barranco
authors.forename: Angel
authors.initials: A
authors.lastname: Rodríguez
authors.forename: Manuel
authors.initials: M
authors.lastname: de Barrio
authors.forename: Mā J
authors.initials: MJ
authors.lastname: Trujillo
authors.forename: Consolación
authors.initials: C
authors.lastname: de Frutos
authors.forename: Víctor
authors.initials: V
authors.lastname: Matheu
authors.forename: Pilar
authors.initials: P
authors.lastname: Tornero
authors.forename: Teresa
authors.initials: T
authors.lastname: Herrero
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000485:Allergens / Q000009:adverse effects / Q000276:immunology*; D003233:Conjunctivitis, Allergic / Q000276:immunology*; D003429:Cross Reactions; D017449:Dermatitis, Allergic Contact / Q000276:immunology*; D004121:Dimethyl Sulfoxide; D004809:Ephedrine / Q000276:immunology; D004983:Ethanolamines / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D008729:Methoxamine / Q000276:immunology; D008875:Middle Aged; D009184:Mydriatics / Q000009:adverse effects / Q000276:immunology*; D010109:Oxymetazoline / Q000276:immunology; D010328:Patch Tests / Q000379:methods; D010656:Phenylephrine / Q000276:immunology; D010665:Phenylpropanolamine / Q000276:immunology; D016037:Single-Blind Method; D013566:Sympathomimetics / Q000009:adverse effects / Q000276:immunology*; D013997:Time Factors
chemical_list: D000485:Allergens; D004983:Ethanolamines; D009184:Mydriatics; D013566:Sympathomimetics; D010656:Phenylephrine; D010665:Phenylpropanolamine; C078462:fepradinol; D010109:Oxymetazoline; D004809:Ephedrine; D008729:Methoxamine; D004121:Dimethyl Sulfoxide