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Updated: Dec 14, 2025

An Ex vivo Mast Cell Degranulation Assay using Crude Peritoneal Exudate Cells and Natural Antigen Stimulation
Published on: April 27, 2021
COVID-19: Famotidine, Histamine, Mast Cells, and Mechanisms
Robert W Malone1, Philip Tisdall2, Philip Fremont-Smith3
1RW Malone MD LLC, Madison, VA.
Abstract:
SARS-CoV-2 infection is required for COVID-19, but many signs and symptoms of COVID-19 differ from common acute viral diseases. Currently, there are no pre- or post-exposure prophylactic COVID-19 medical countermeasures. Clinical data suggest that famotidine may mitigate COVID-19 disease, but both mechanism of action and rationale for dose selection remain obscure. We explore several plausible avenues of activity including antiviral and host-mediated actions. We propose that the principal famotidine mechanism of action for COVID-19 involves on-target histamine receptor H2 activity, and that development of clinical COVID-19 involves dysfunctional mast cell activation and histamine release.
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