It also demonstrated lower levels of serum markers for severe disease.
The findings come from an observational study of 83 hospitalized patients that was published in the American Journal of Gastroenterology.
“The mechanism of exactly how famotidine works has yet to be proven,” lead study author Jeffrey F. Mather, MS, said in an interview. “There’s thought that it works directly on the virus, and there is thought that it works through inactivating certain proteases that are required for the virus infection, but I think the most interesting [hypothesis] is by Malone et al. “They’re looking at the blocking of the histamine-2 receptor causing a decrease in the amount of histamine. It’s all speculative, but it will be interesting if that gets worked out.”
In a study that largely mimicked that of an earlier, larger published observational study on the topic (doi: 10.1053/j.gastro.2020.05.053), Mr. Mather and colleagues retrospectively evaluated 878 patients who tested positive for SARS-CoV-2 and who required admission to Hartford (Conn.) Hospital between Feb. 24, 2020, and May 14, 2020. Patients were classified as receiving famotidine if they were treated with either oral or intravenous drug within 1 week of COVID-19 screening and/or hospital admission. Primary outcomes of interest were in-hospital death as recorded in the discharge of the patients, requirement for mechanical ventilation, and the composite of death or requirement for ventilation. Secondary outcomes of interest were several serum markers of disease activity including white blood cell count, lymphocyte count, and eosinophil count.
Famotidine was administered orally in 83% of the patients and intravenously in the remaining 17%. Mr. Mather, director of data management in the division of research management at Hartford Hospital, and his colleagues reported that 83 of the 878 patients studied (9.5%) received famotidine. Compared with patients not treated with famotidine, those who received the drug were slightly younger (a mean of 64 vs. 68 years, respectively; P = .021); otherwise, there were no differences between the two groups in baseline demographics or in preexisting comorbidities.
The use of famotidine was associated with a decreased risk of in-hospital mortality (odds ratio, 0.37; P = .021) as well as combined death or intubation (OR, 0.47; P = .040). The outcomes were similar when the researchers performed propensity score matching to adjust for age differences between groups.
In addition, the use of famotidine was associated with lower levels of serum markers for severe disease including lower median peak C-reactive protein levels (9.4 vs. 12.7 mg/dL; P =. 002), lower median procalcitonin levels (0.16 vs. 0.30 ng/mL; P = .004), and a nonsignificant trend to lower median mean ferritin levels (797.5 vs. 964 ng/mL; P = .076).
Logistic regression analysis revealed that use of famotidine was an independent predictor of both lower mortality and combined death/intubation. In addition, predictors of both adverse outcomes included older age, a body mass index of greater than 30 kg/m2, chronic kidney disease, the national early warning score, and a higher neutrophil-lymphocyte ratio.
“This is an important stepping stone, but until we have a randomized, controlled trial, we really can’t speak about causation; we can only speak about association, and that’s okay,” Brennan Spiegel, MD, MSHS, director of health services research at Cedars-Sinai, Los Angeles, who was not affiliated with the study, said in an interview. “There’s nothing wrong with association because finding associations can raise important hypotheses that can then be tested in prospective randomized trials, for example.”
In July 2020, Dr. Spiegel and his colleagues published a separate paper looking at proton pump inhibitors and the risk of COVID-19. “In that study we did look at H2 blockers, and we did find that they were slightly associated with a reduction in COVID-19,” he said. “It was a small effect, but it was a benefit. When we see consistency among studies, it’s a signal in the noise we can try and follow and see if there is something more to it.”
Mr. Mather acknowledged certain limitations of the study, including the fact that patients who did and did not receive famotidine were propensity-matched for age. “The risk factors that others have shown for adverse events are equivalent in the groups, but anytime you do a retrospective study like this there is the potential for underlying factors that may play a role in the outcomes that you’re not considering,” Mr. Mather said. “That’s why the gold standard is the randomized trial, to wash those effects out. There’s only an association here, and it supports the need for a randomized trial.”
Famotidine is currently being tested in a double-blind randomized clinical trial in combination with either hydroxychloroquine or remdesivir (NCT 04370262).
“It’s fascinating because famotidine is a safe medicine,” added Dr. Spiegel, who is also co–editor in chief of the American Journal of Gastroenterology. “There are very few side effects; it’s something we’ve been using for decades.”
Mr. Mather and his colleagues reported having no financial disclosures. Dr. Spiegel disclosed that he has served on advisory boards for Allergan, Alnylam Pharmaceuticals, Arena Pharmaceuticals, Ironwood Pharmaceuticals, Salix Pharmaceuticals, Synergy Pharmaceuticals, and Takeda Pharmaceuticals.
SOURCE: Mather J et al. 2020 Aug 14. Am J Gastroenterol.