title: Oral challenge test with sodium metabisulfite in steroid-dependent asthmatic patients.
abstract: Oral challenge tests were carried out with sodium metabisulfite solution doses of 0.5, 1, 10, 25, 50 mg and encapsulated doses of 100 and 200 mg, as well as with lactose-placebo, on 44 non-atopic patients with steroid-dependent bronchial asthma, without clinical evidence of intolerance to these agents. Only those patients with an acceptable and not very labile pulmonary function were tested. A single-blind challenge protocol was performed in 22 patients (sodium metabisulfite solutions at pH 2.2 to 2.6) and the positive responses were confirmed by double-blind challenge. The other 22 were tested directly in a double-blind manner (pH4). Initially, 6/44 presented a positive reaction. However, a careful analysis and the confirmation by double-blind challenge of the positive responses obtained with the single-blind test, allowed us to identify 4 false positive responses. Thus, the true prevalence of sulfite sensitivity in our population is 4.5%. A patient with intolerance to sulfite agents also suffered aspirin-induced asthma. The labile tendency of the pulmonary function of the asthmatic patients may have contributed to some false positive reactions and probably explain the very high prevalence found in some studies. It does not appear that the variations of pH decisively influence the result of the challenge test.
authors.affiliation: Sección de Alergia y Servicio de Farmacia, Hospital Doctor Peset, Valencia, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Prieto
authors.forename: M
authors.initials: M
authors.lastname: Juyol
authors.forename: A
authors.initials: A
authors.lastname: Paricio
authors.forename: M A
authors.initials: MA
authors.lastname: Martínez
authors.forename: J
authors.initials: J
authors.lastname: Palop
authors.forename: J
authors.initials: J
authors.lastname: Castro
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000009:adverse effects*; D001249:Asthma / Q000139:chemically induced / Q000175:diagnosis* / Q000188:drug therapy; D003430:Cross-Sectional Studies; D004311:Double-Blind Method; D005189:False Positive Reactions; D005260:Female; D005520:Food Preservatives / Q000009:adverse effects*; D005541:Forced Expiratory Volume; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D013447:Sulfites / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D000305:Adrenal Cortex Hormones; D000975:Antioxidants; D005520:Food Preservatives; D013447:Sulfites; C005200:sodium metabisulfite