Hong Kong researchers demonstrate that the already available and cheap ulcer drug “Tritec”
ranitidine bismuth citrate
may have potential as an effective Covid-19 fighter.

https://news.yahoo.com/hong-kong-scientists-anti-microbe-042106404.html

Sample quote

Using Syrian hamsters as tests subjects, they found that one of the drugs,
ranitidine bismuth citrate (RBC),
was "a potent anti-SARS-CoV-2 agent".

"RBC is able to lower the viral load in the lung of the infected hamster by tenfold,"
Hong Kong University researcher Runming Wang told reporters on Monday as the team presented their study.

End quote

More technical information:

https://www.nature.com/articles/s41564-020-00802-x