Renal replacement therapy removes a large number of nitric oxide donors responsible for the nitrate-nitrite-nitric oxide pathway.

BACKGROUNDS: Nitric oxide has a broad-spectrum antibacterial property promising as a new therapeutic agent for severe acute respiratory syndrome coronavirus-2 because nitric oxide donor (such as S-nitroso-N-acetylpenicillamine) reduces the replication of coronavirus-2. Patients with coronavirus disease 2019 undergoing dialysis generally have a higher mortality rate than the general population. Although the higher mortality rate in these patients may be related to their advanced age, it has been suggested that plasma nitrite and nitrate levels (products of nitric oxide metabolism) are significantly decreased after hemodialysis which may compromise the nitrate-nitrite-nitric oxide pathway and impair nitric oxide homeostasis. It results in increased cardiovascular mortality in patients undergoing dialysis. However, the profile of nitric oxide-producing substances is poorly understood during renal replacement therapy. METHODS: We simulated continuous hemodialysis and hemodiafiltration to measure the amount of nitric oxide (nitric oxide-producing substance) clearance in vitro. RESULTS: The results demonstrated increased nitric oxide clearance and higher clearance than creatinine (molecular weight: 113) and vitamin B12 (molecular weight: 1355) using highly efficient renal replacement therapy modes. CONCLUSION: The high nitric oxide clearance may have partly contributed to the high cardiovascular and coronavirus-2 mortality risk in patients on dialysis.

Harnessing nitric oxide for preventing, limiting and treating the severe pulmonary consequences of COVID-19.

The ongoing outbreak of COVID-19 has quickly become a daunting challenge to global health. In the absence of targeted therapy and a reported 5.5% case fatality rate in the United States, treatments preventing rapid cardiopulmonary failure are urgently needed. Clinical features, pathology and homology to better understood pathogens suggest that uncontrolled inflammation and a cytokine storm likely drive COVID-19's unrelenting disease process. Interventions that are protective against acute lung injury and ARDS can play a critical role for patients and health systems during this pandemic. Nitric oxide is an antimicrobial and anti-inflammatory molecule with key roles in pulmonary vascular function in the context of viral infections and other pulmonary disease states. This article reviews the rationale for exogenous nitric oxide use for the pathogenesis of COVID-19 and highlights its potential for contributing to better clinical outcomes and alleviating the rapidly rising strain on healthcare capacity.

Desperate Times, Desperate Measures: The Case for RRx-001 in the Treatment of COVID-19.

This article summarizes the likely attenuation properties of RRx-001 in COVID-19 based on its mechanism of action and the putative pathogenesis of the disease, which appears to activate inflammatory, oxidative, and immune cascades with the potential to culminate in acute respiratory distress syndrome, cytokine storm and death. An ongoing pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), COVID-19 appears to present with 3 major patterns of clinical symptomatology: (1) mild upper respiratory tract infection, (2) non-life-threatening pneumonia, and (3) severe pneumonia and acute respiratory distress syndrome that initially manifest as a mild prodrome lasting for 7-8 days before rapid clinical and radiological deterioration requiring ICU transfer. RRx-001 is a targeted nitric oxide donor. This small molecule, which has been evaluated in multiple Phase 1-2 clinical trials for cancer as well as a Phase 3 clinical trial for the treatment of small cell lung cancer called REPLATINUM (NCT03699956), is minimally toxic and demonstrates clear evidence of antitumor activity. During the course of these clinical trials it was noted that the rate of chronic obstructive pulmonary disease exacerbation and pneumonia in actively smoking small cell lung cancer patients treated with RRx-001 is less than 1%. Due to extensive history of tobacco use, 40%-70% of patients with lung cancer have chronic obstructive pulmonary disease and the expected rate of pulmonary infection in this population is 50%-70%, which was not observed in RRx-001 clinical trials. Moreover, in preclinical studies of pulmonary hypertension, RRx-001 was found to be comparable with or more effective than the FDA approved agent, Bosentan. The potential pulmonary protective effects of RRx-001 in patients with recurrent lung infections coupled with preclinical models demonstrating RRx-001-mediated reversal of pulmonary hypertension suggests RRx-001 may have therapeutic activity in patients with acute respiratory symptoms due to COVID 19. Clinical trials have been initiated to confirm the hypothesis that RRx-001 may be repurposed to treat SARS-CoV-2 infection.