Specific inhalation challenges (SICs) with low-molecular-weight agents are associated with a higher risk of an asthmatic reaction requiring pharmacological treatment, according to new research out of Belgium. The authors believe their findings could provide useful guidelines for further improving the safety of SICs, which are rarely used in part because of concerns over safety.
For the study, patients treated at a single center were exposed to a control agent on day one and a suspected occupational agent on day two. Of these tests, 206 were exposed to high molecular weight (HMW) agents; 123 with low molecular weight (LMW) agents.
In total, 20% of patients needed an inhaled short-acting beta-agonist (SABA) following the SIC. Multivariate analysis showed that SIC involving a LMW agent increased the odds for needing inhaled SABA 2.5-fold (54% vs 32% of patients). Of the asthmatic reactions, 40 were graded as moderate, 10 as severe, and 1 as life-threatening. According to researchers, SIC involving a LMW agent was the only significant predictor of a moderate or severe reaction, increasing the odds threefold compared with HMW agents (60% vs 33%).
The authors note that the majority of severe reactions took place within the first hour of exposure and half developed after exposures of 5 minutes or less, showing that even short exposures carry the risk for a severe reaction and highlighting the importance of the first hour as a critical time window for close observation.