Effects of adding L-arginine orally to standard therapy in patients with COVID-19: A randomized, double-blind, placebo-controlled, parallel-group trial. Results of the first interim analysis
Giuseppe Fiorentino EclinicalMed September 09, 2021
Background
We and others have previously demonstrated that the endothelium is a primary target of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and L-arginine has been shown to improve endothelial dysfunction. However, the effects of L-arginine have never been evaluated in coronavirus disease 2019 (COVID-19).
Methods
This is a parallel-group, double-blind, randomized, placebo-controlled trial conducted on patients hospitalized for severe COVID-19. Patients received 1.66 g L-arginine twice a day or placebo, administered orally. The primary efficacy endpoint was a reduction in respiratory support assessed 10 and 20 days after randomization. Secondary outcomes were the length of in-hospital stay, the time to normalization of lymphocyte number, and the time to obtain a negative real-time reverse transcription polymerase chain reaction (RT-PCR) for SARS-CoV-2 on nasopharyngeal swab.
Findings
We present here the results of the initial interim analysis on the first 101 patients. No treatment-emergent serious adverse events were attributable to L-arginine. At 10-day evaluation, 71.1% of patients in the L-arginine arm and 44.4% in the placebo arm (p < 0.01) had the respiratory support reduced; however, a significant difference was not detected 20 days after randomization. Strikingly, patients treated with L-arginine exhibited a significantly reduced in-hospital stay vs placebo, with a median (interquartile range 25th,75th percentile) of 46 days (45,46) in the placebo group vs 25 days (21,26) in the L-arginine group (p < 0.0001); these findings were also confirmed after adjusting for potential confounders including age, duration of symptoms, comorbidities, D-dimer, as well as antiviral and anticoagulant treatments. The other secondary outcomes were not significantly different between groups.
Interpretation
In this interim analysis, adding oral L-arginine to standard therapy in patients with severe COVID-19 significantly decreases the length of hospitalization and reduces the respiratory support at 10 but not at 20 days after starting the treatment.
Research in context
Evidence before this study
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV- 2) infection has spread worldwide, causing disease and mortality, as well as social disruption and economic loss. Endothelial cells have been shown to be a cardinal target in COVID-19, and L-arginine is known to improve endothelial dysfunction. PubMed and medRxiv preprint searches were updated on June 24, 2021 using the search criteria "SARS-CoV-2" "COVID-19" “L-arginine”. These searches retrieved no items.
Added value of this study
The first interim analysis of this randomized, double-blind, placebo-controlled, parallel-group trial shows that patients hospitalized for severe COVID-19 treated with L-arginine displayed a significantly reduced in-hospital stay vs placebo (log-rank p < 0.0001). Furthermore, at the 10-day evaluation, 71.1% of patients in the L-arginine group and 44.4% in the placebo group (p < 0.01) had reduced the respiratory support; however, a significant difference was not detected 20 days after randomization, most likely because most of the participants in the L-arginine arm had been already discharged from the hospital by this time.
Implications of all the available evidence
There is concrete evidence that endothelial dysfunction is a fundamental feature of COVID-19. However, no clinical trial has actually shown that intervention improving endothelial function could be beneficial in COVID-19. Our interim findings indicate for the first time that adding L-arginine orally to standard therapy in patients with severe COVID-19 significantly reduces the length of hospital stay and respiratory support.