Essentials in saline pharmacology for nasal or respiratory hygiene in times of COVID-19

Suzy Huijghebaert, Levi Hoste, Guido Vanham, Suzy Huijghebaert, Levi Hoste, Guido Vanham

Abstract

Purpose: Nasal irrigation or nebulizing aerosol of isotonic or hypertonic saline is a traditional method for respiratory or nasal care. A recent small study in outpatients with COVID-19 without acute respiratory distress syndrome suggests substantial symptom resolution. We therefore analyzed pharmacological/pharmacodynamic effects of isotonic or hypertonic saline, relevant to SARS-CoV-2 infection and respiratory care.

Methods: Mixed search method.

Results: Due to its wetting properties, saline achieves an improved spreading of alveolar lining fluid and has been shown to reduce bio-aerosols and viral load. Saline provides moisture to respiratory epithelia and gels mucus, promotes ciliary beating, and improves mucociliary clearance. Coronaviruses and SARS-CoV-2 damage ciliated epithelium in the nose and airways. Saline inhibits SARS-CoV-2 replication in Vero cells; possible interactions involve the viral ACE2-entry mechanism (chloride-dependent ACE2 configuration), furin and 3CLpro (inhibition by NaCl), and the sodium channel ENaC. Saline shifts myeloperoxidase activity in epithelial or phagocytic cells to produce hypochlorous acid. Clinically, nasal or respiratory airway care with saline reduces symptoms of seasonal coronaviruses and other common cold viruses. Its use as aerosol reduces hospitalization rates for bronchiolitis in children. Preliminary data suggest symptom reduction in symptomatic COVID-19 patients if saline is initiated within 48 h of symptom onset.

Conclusions: Saline interacts at various levels relevant to nasal or respiratory hygiene (nasal irrigation, gargling or aerosol). If used from the onset of common cold symptoms, it may represent a useful add-on to first-line interventions for COVID-19. Formal evaluation in mild COVID-19 is desirable as to establish efficacy and optimal treatment regimens.

Keywords: Acute respiratory distress syndrome; COVID-19; Mucociliary clearance; SARS-CoV-2; Saline; Sodium chloride.

Conflict of interest statement

The authors declare no competing interests.

© 2021. The Author(s).

Figures

Fig. 1
Fig. 1
Proposed mechanisms of saline relevant to nasal or respiratory hygiene during COVID-19. Bio-aerosol refers to micro-droplets, spontaneously produced during exhalation, such as during speaking, singing, and coughing; aerosol refers to nebulizing and inhaling saline for inhalation in the respiratory airways, while saline rinse refers to nasal spraying/oral gargling of saline. ALF, alveolar lining fluid; isotonic, 0.9% NaCl (or 9 g/L); and hypertonic, varying concentrations above 0.9% NaCl (2%-7%, often 3%). ACE2 angiotensin-converting enzyme 2; MCC mucociliary clearance

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