Phase IIa randomized placebo-controlled clinical trial to evaluate the efficacy of bromhexine in combination with standard therapy in the early treatment of COVID-19 in primary care patients

The continuous appearance of SARS-CoV-2 variants with both increased transmission and immune evading potential, in addition to the reluctance of some populations to be vaccinated, supports the search for alternative treatments to protect against the viral infection consequences. Bromhexine is a well-known, over-the counter, expectorant which have garnered interest for the potential prevention and treatment of COVID-19. Here, we report the results of a placebo-controlled randomized clinical trial in which the efficacy of oral bromhexine was tested in outpatients with mild to moderate symptomatic COVID-19. Adult patients diagnosed with active SARS-CoV-2 infection were randomly assigned (1:1) to receive bromhexine or placebo, with both groups also receiving standard care. The primary efficacy endpoint was viral load reduction (day 4 vs. baseline), while reductions of a series of COVID-19 clinical symptoms were considered as secondary endpoints. No differences in the viral load at different times after the initiation of treatment were observed. In addition, no differences between groups were detected in most of the clinical symptoms evaluated. Remarkably, a significant decrease in the percentage of patients with cough was observed at days 5-7 in the bromhexine group, an effect that was not apparent in the group receiving a placebo. Since coughing is one of the main forms of transmission for SARS-CoV-2, this effect might be highly beneficial in particularly for patients living in crowded, poorly ventilated, or confined environments.