Can long term add-on doxycycline improve lung function in asthma: The result of an open prospective real-world observation

Background: The inhibition of matrix metalloproteinases and IgE could be a prospective target of treating inflammation and remodelling of asthma. Doxycycline, a known antibiotic may qualify for the job for having both the properties. Objective: To look for effect on long term add-on oral doxycycline in patients of asthma. Methods: In an open prospective, real-world observation, a cohort of asthmatics was given to choose treatment either with a “standard” therapy (long-acting β-2 agonist + inhaled corticosteroid) or with the same and add-on long term doxycycline orally. The changes in postbronchodilator FEV1, FEV1/FVC, and FEF25–75 were noted for comparison with repeat spirometry after nearly a year. Results: The two groups (standard therapy alone [n = 73] and standard therapy plus doxycycline [n = 72]) were similar (p < 0.05) as regards to age and BMI, but the subjects opting for add-on doxycycline had significantly lower baseline postbronchodilator FEV1 (1.25 ± 0.50 and 1.66 ± 0.73 Litres; p < 0.0001). Both the groups had received treatment for similar length of time (346.89 ± 269.61 and 335.82 ± 274.51 days, respectively). The add-on doxycycline group had a significant improvement in absolute value of postbronchodilator FEV1 (130 mL [p = 0.0000]), whereas the subjects on standard therapy alone showed a reduction (70 mL [p = 0.027]) compared to the baseline values. There was a parallel increase in FEV1/FVC (p < 0.005) and FEF25-75 (p < 0.0001) in the doxycycline-treated patients, suggesting an overall improvement in airflow limitations. Conclusion: The add-on oral doxycycline tolerated well on long term and resulted in a significant improvement in spirometric indices of airflow limitations in the asthmatics. The observation deserves further validation.