Occupational asthma caused by isonicotinic acid hydrazide (INH) inhalation.

Occupational asthma caused by isonicotinic acid hydrazide (INH) inhalation occurred in a 26-year-old female hospital pharmacist after symptoms of allergic rhinitis. Intradermal, inhalation, and Prausnitz-Küstner tests were performed with INH dissolved in saline, INH dissolved in the subject's serum and incubated at 25 degrees C for 4 hours, and an INH conjugate with human serum albumin. An INH conjugate with bovine serum albumin was also used in the prick tests alone. All preparations caused rapid positive skin reaction in the patient. Prausnitz-Küstner tests on the subject's mother were also rapidly positive. Furthermore, positive results were obtained not only in the inhalation tests with the three antigens but also in the environmental provocation tests. These results strongly suggested that the asthmatic symptoms of the subject were not caused by physical irritation from INH or other drugs and might be mediated by an IgE antibody specific to INH, a suggestion subsequently confirmed by in vitro enzyme-linked allergosorbent test for the antibody previously reported. This is the first precise description of INH-induced bronchial asthma, and the four kinds of INH preparations used in these tests might be very useful as tools of clinical diagnosis in INH allergy.