A retrospective study on potential drug‒drug interactions in patients with severe asthma receiving biological therapy: a single-center experience.

Background: Prevalence of potential drug-drug interactions (pDDIs) in adult patients with severe asthma on biological therapy and their clinical significance have not been fully addressed, thus the aim of this study was to investigate them.

Methods: In this retrospective observational study, patients who were diagnosed with severe asthma and to whom biological therapy was prescribed between September 2015 and December 2020, were enrolled. The study was conducted at the Department of Allergic and Obstructive Pulmonary Diseases, Clinic for Lung Diseases Jordanovac, Clinical Hospital Center Zagreb. Data on demographic characteristics as well as concomitant medication were collected. The analysis of pDDIs was conducted via Lexicomp^® online software. Interactions of significance levels A and B were only recorded, while those of levels C, D and X were further analysed. The collected data was processed via Microsoft Excel 365 software.

Results: 60 adult patients, 60% female and 40% male, with median age of 56.2 years, were enrolled. The incidence of pDDIs was 86.67%. Total number of pDDIs detected was 518, out of which 43.24%, 45%, 4.44% and 7.3% of clinical significance B, C, D and X. Interactions of level C, D and X were recorded in, as follows: 83.33%, 25% and 33.33% patients with an average of 4.66, 1.53 and 1.9 interactions per patient. Only 13.33% of the patients had none of the potential clinically significant DDI. Most drug pairs contained at least one antiasthmatic drug. Muscarinic receptor antagonists, oral corticosteroids, β2 agonists and methylxanthines showed potential of entering into clinically significant DDIs, while leukotriene antagonists and biologicals showed no potential for the above.

Conclusion: Prevalence of potential drug-drug interactions in patients with severe asthma on biological therapy is high. The majority of identified interactions have moderate to high level of clinical significance. Their identification, prevention and resolution could contribute to optimizing therapy, maximizing its therapeutic effect and avoiding undesirable adverse events.