Remdesivir could be one of the drugs used to treat the coronavirus, but other options are now giving it a run for its money. Studies from Hong Kong and the U.S. have found that a stomach ulcer drug and a blood cancer drug are potentially more effective. Anne Cheng has more.

As scientists continue to develop vaccines to help prevent the Coronavirus, others have chosen to focus their efforts on the treatment side of it.

A research team at The University of Hong Kong has discovered that a drug commonly used to treat stomach ulcers can be effective against COVID-19.

The published and peer-reviewed results found that ranitidine bismuth citrate, or RBC, can reduce viral loads by over a thousand times in cellular levels. Meanwhile, the virus can be reduced by at least ten-fold in a hamster.

The research team says RBC is just as good or even better than Remdesivir, the approved Coronavirus drug.

SUN HONGZHE Norman & Cecilia Yip Professor in Bioinorganic Chemistry The University of Hong Kong "In terms of therapeutic window, Remdesivir is about 130, and ranitidine bismuth citrate is about 975 – it's about over five-fold differences. In other words, in terms of toxicity for this, ranitidine bismuth citrate shall be much lower than the Remdesivir under similar dosages. So that's what we are very excited about, because safety is one of the important parameters for future clinical applications."

He also says the drug costs less than a quarter of Remdesivir, which is over U.S.$3,000 a course, so price is another important issue to consider when millions of people are concerned.

RBC works by inhibiting Nsp13, a viral protein, from unwinding human DNA to self-replicate. Sun doesn't expect much resistance to this drug, because regardless of mutations, the virus needs to maintain this unwinding function to survive.

This study has been filed for a patent in the U.S..

Meanwhile, a study, led by the University of California-San Francisco, has also discovered that an existing cancer drug, derived from sea squirts, can significantly outshine Remdesivir.

The published and peer-reviewed results found that Plitidepsin is 27.5 times more potent in human cells than Remdesivir. It was also found that the virus can be reduced by 100 to 500 times in mice.

Plitidepsin, developed by Spanish drug maker PharmaMar, is currently approved under the brand name Aplidin to treat multiple myeloma.

While Remdesivir works by targeting a viral protein, Plitidepsin targets a human protein, EIF1a, which the virus needs to live and replicate its own proteins.

NEVAN KROGAN Director of The Quantitative Biosciences Institute University of California San Francisco "One of the advantages of targeting a host protein is that we don't have to worry about mutations. We don't have to worry about resistance to the drug because we don't mutate, not nearly as fast as the virus. The virus will never be able to mutate enough to overcome its reliance on the human protein."

He adds that the drug is found to be equally potent against the UK variant, so its consistent effectiveness puts it in a much better position for the next pandemic.

Krogan also says two phases of clinical trials have already been conducted with promising results, and an upcoming third phase is expected soon.

ANNE CHENG Hong Kong "The studies on RBC and Plitidepsin involve the repurposing of already approved drugs, which both experts say may help speed up the approval process for use against COVID-19. Both have also suggested the drugs will likely be most effective in a cocktail, but what does that combination look like? That'll be a matter of more time and research. Anne Cheng, CGTN, Hong Kong."