麻豆传媒

Self-administered high-dose oral famotidine (Pepcid AC) was well tolerated and associated with improved patient-reported outcomes in non-hospitalized COVID-19 patients, a small case series found.

At daily doses ranging from 60 to 240 mg, the histamine-2 receptor antagonist widely used to suppress gastric acid production was linked to reduced severity across a range of symptoms 24 to 48 hours after starting treatment in 10 outpatients with a clinical diagnosis of COVID-19, reported Tobias Janowitz, MD, PhD, of Cold Spring Harbor Laboratory in New York. Symptoms cleared within 14 days, the team said.

"Our findings support the rigorous evaluation of famotidine as a potential therapy and of the use of symptom tracking for non-hospitalized patients with COVID-19," the researchers wrote in their study online in .

The team cautioned, however, that for now the case series only suggests a benefit of famotidine, and it's not clear how famotidine might work in COVID-19 -- for example, whether it might incapacitate the virus in some way or perhaps alter a person's immune response.

For example, the investigators speculated, famotidine could have a viral target, such as one of the viral proteases or a host therapeutic target involved in modulating the immunological response to the virus. Chinese researchers recently predicted the encoded by the SARS-CoV-2 coronavirus genome and identified famotidine as one of the drugs most likely to inhibit 3-chymotrypsin-like protease, the enzyme that processes proteins essential for viral replication.

In addition, a from New York suggested a beneficial effect of famotidine in hospitalized COVID-19 patients, reducing the risk of clinical deterioration leading to intubation or death.

Study Details

In the new study, the 10 consecutively enrolled patients -- nine from the U.S. and one from Sweden -- included six men and four women, and several racial/ethic groups: white, black, Hispanic, black-Hispanic, Asian, and South Asian. Patients ranged in age from 23 to 71, although most were middle-age.

Several of the patients had some severity-related lifestyle practice or comorbidity such as smoking, obesity, hypertension, or hyperlipidemia. Reported symptoms included body aches, fever, sweating, chest tightness, nasal congestion, and sore throat. The severity of five symptoms was quantitatively tracked by patients on a scale of 1 (least severe) to 4 (most severe).

All patients reported taking self-administered oral famotidine, with 80 mg three times a day the most frequent dose, and the average treatment period was 11 days (range 5-21).

In one case, a 44-year-old white woman with a medical history of epilepsy took famotidine 80 mg three times daily for 11 days starting 4 days after first experiencing symptoms of COVID-19. She reported that after feeling very unwell at the outset, within 1 day of the first dose of famotidine, she noticed marked improvement in her shortness of breath. This improvement was matched by an increase in her home-monitored pulse oximetry-measured oxygen saturation levels, which rose from 91-95% to 97-98%. Before starting the drug, she was febrile with a temperature of 37.8°C, but was afebrile by day 7 of treatment.

No adverse events emerged in seven participants, while one reported grade 1 dizziness and occasional racing heartbeat. Another had grade 1 dizziness, dry skin, and insomnia, and a third reported grade 1 gastrointestinal symptoms and temporary forgetfulness, all of which except for the last are listed side effects of the drug. No patient required later admission to the hospital.

Asked for her perspective, Yamini Natarajan, MD, of Baylor College of Medicine in Houston, who was not involved with the study, said the results support further investigation of the effects and the mechanism of action of this medication. She cautioned, however, that patients in non-blinded studies may be subject to the placebo effect and register improvement just by taking the medication, rather than the improvement being the result of the medication itself.

"This study is a case series, which means that there is no control, or comparison, group. As the authors themselves state, this study does not recommend widespread use of of famotidine for COVID, but it does suggest that further research should be done in a way that minimizes bias," she told 麻豆传媒.

A randomized has recently been launched to test the efficacy of high-dose intravenous famotidine three times daily in addition to hydroxychloroquine in hospitalized patients with COVID-19. Janowitz and co-authors also recommended an outpatient study of oral famotidine for symptom control, viral burden, disease outcome, and impact on long-term immunity and transmission.

Study limitations, the researchers noted, included the possible placebo effect, enrollment bias, and recall bias regarding symptoms, which may have affected the findings as in any non-blinded, non-controlled study, despite the attempt to minimize bias by asking non-leading questions, the team said. Furthermore, it is possible that improvements in symptoms might have been due to treatment-independent convalescence since the natural course of COVID-19 in patients not requiring hospital admission is not well characterized.

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