Bronchospastic responses to aerosolized metabisulfite in asthmatic subjects: potential mechanisms and clinical implications.

Eight asthmatic patients with a history suggestive of sulfite sensitivity were studied, six of whom had a positive oral challenge to doses from 10 mg to 50 mg. All eight patients had aerosol metabisulfite challenge; six positive tests were observed at doses of 0.5 mg/ml and 5.0 mg/ml. Aerosolizing solutions of metabisulfite at 5.0 mg/ml generated significant amounts of free sulfur dioxide. Implications of these findings are discussed.