Azithromycin and ambroxol as potential pharmacotherapy for SARS-CoV-2

Knowing the ability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to bind to the angiotensin-converting enzyme 2 (ACE2) receptor and to enter cells via endocytosis paved the way for repositioning of old drugs as potential treatment of COVID-19, the disease caused by SARS-CoV-2 infection. This paper highlights the potential of azithromycin and ambroxol to treat COVID-19. Azithromycin and ambroxol share lysosomotropic characteristics, i.e. they penetrate and accumulate inside the late endosomes and lysosomes and may possibly interfere with multiplication of the virus inside cells. In addition, both of these drugs have anti-inflammatory effects. Ambroxol has a proven antiviral effect and a unique stimulatory action on the secretion of surfactant by alveolar type II cells, the main target of SARS-CoV-2. Surfactant may form a fundamental defence mechanism against the virus. Involvement of nasal epithelial cells in SARS-CoV-2 entry suggested advantageous use of inhaled drug delivery of these two drugs over the use of systemic administration. Inhaled drug delivery could aid in targeting the drug to the exact site of action with little or no side effects. To conclude, administration of these two drugs using a special drug delivery system provides two kinds of drug targeting: (i) tissue targeting through using an inhaled drug delivery system to achieve high drug concentrations at the respiratory epithelial tissue that overexpress the ACE2 receptor for virus binding; and (ii) cellular targeting of the virus in the acidic vesicles (late endosomes and lysosomes), which represent the fate of endocytic viruses.