H2RAs and COVID-19
H2RA also suppresses the production of gastric acid. Cimetidine,
ranitidine, famotidine and nizatidine are examples of H2RAs. Early data
show that H2RAs had antiviral properties inhibiting HIV replication in
vitro (21). Famotidine’s role in SARS-CoV-2 was elucidated in a study by
Wu et al. (22). There is a potential role of famotidine in interfering
maturation of SARS-CoV-2 and reducing inflammation. This knowledge has
spurred an interest in the potential of the drug.
The results of a recent propensity score-matched retrospective cohort
study involving hospitalised COVID-19 patients in New York were
promising (13). This study by Freedberg et al. showed that in patients
hospitalised with COVID-19 and not initially intubated, famotidine use
was associated with a two-fold reduction in clinical deterioration
leading to intubation or death (adjusted hazard ratio 0.42, 95% CI
0.21–0.85). However, this effect was not observed in PPI users for
unclear reasons.
Similarly, a study by Janowitz et al., revealed self-administration of
famotidine is associated with symptomatic improvements in a case series
of 10 consecutive patients (14). The results of this case series suggest
that high-dose oral famotidine is well tolerated and associated with
improved patient-reported outcomes in non-hospitalised patients with
COVID-19.
The findings of the above two studies are observational and should not
be interpreted to mean that famotidine has a protective effect against
COVID-19. Currently, clinical trials are underway to determine whether
H2RAs might protect against the COVID-19 for reasons unrelated to pH
balance. The results of a multicentre, randomised controlled trial (RCT)
(NCT04370262) of intravenous famotidine in COVID-19 is eagerly awaited
(23).