title: Immunoglobulin E-mediated hypersensitivity to amoxicillin: in vivo and in vitro comparative studies between an injectable therapeutic compound and a new commercial compound.
abstract: BACKGROUND
  Skin testing with amoxicillin (AX) is necessary to diagnose immediate hypersensitivity reactions to this β-lactam. A commercial AX (DIA-AX) has recently become available for skin testing.
  
  
  OBJECTIVE
  The aim of this study was to compare DIA-AX with the injectable form (INJ-AX) in patients who have well-demonstrated IgE-mediated hypersensitivity to AX.
  
  
  METHODS
  Chemical characterization using high-performance liquid chromatography of both DIA-AX and INJ-AX reagents was performed. Patients diagnosed with an immediate allergic reaction to AX and a positive skin test to INJ-AX (N=55) were re-evaluated within 6 months by performing skin testing with INJ-AX and DIA-AX. Basophil activation test (BAT) and Radioallergosorbent test (RAST) inhibition assay using both reagents were performed in a selected group of patients.
  
  
  RESULTS
  The chemical analysis indicated that both DIA-AX and INJ-AX contained an AX compound with a purity above 95%. In the re-evaluation, 53 (96.4%) cases maintained skin test positivity to INJ-AX and were also positive to DIA-AX. Comparison of the papule area between the two reagents showed no significant differences between both reagents. BAT was performed in 30 samples and was positive to both compounds in 15 cases; no patient had a positive result to just one reagent. RAST inhibition studies using three individual cases and a pool of positive sera showed that the percentage inhibition detected with DIA-AX and INJ-AX was parallel and almost exactly the same.
  
  
  CONCLUSIONS
  This study shows that DIA-AX is equivalent to INJ-AX in terms of skin test response, as well as with in vitro immunochemical and biological tests. DIA-AX can therefore be used in the diagnosis of immediate hypersensitivity reactions.
authors.affiliation: Research Unit for Allergic Diseases, Allergy Service, Carlos Haya Hospital, Málaga, Spain. mjtorresj@gmail.com
authors.forename: M J
authors.initials: MJ
authors.lastname: Torres
authors.forename: A
authors.initials: A
authors.lastname: Romano
authors.forename: N
authors.initials: N
authors.lastname: Blanca-Lopez
authors.forename: I
authors.initials: I
authors.lastname: Doña
authors.forename: G
authors.initials: G
authors.lastname: Canto
authors.forename: A
authors.initials: A
authors.lastname: Ariza
authors.forename: A
authors.initials: A
authors.lastname: Aranda
authors.forename: M I
authors.initials: MI
authors.lastname: Montañez
authors.forename: C
authors.initials: C
authors.lastname: Mayorga
authors.forename: M
authors.initials: M
authors.lastname: Blanca
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000276:immunology*; D000900:Anti-Bacterial Agents / Q000276:immunology*; D004342:Drug Hypersensitivity / Q000175:diagnosis / Q000276:immunology*; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000175:diagnosis / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012882:Skin Tests; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D000658:Amoxicillin