The rapid descent continues for hydroxychloroquine as hope for a cure for COVID-19. On Monday, pharmaceutical giant Novartis (NYSE:NVS) announced that it is stopping the sponsored clinical trial it was conducting on the treatment of COVID-19 with the drug.

The company says this is "due to acute enrollment challenges that have made trial completion infeasible." It stressed that no safety issues had been reported from the study. On the other hand, it reached no conclusions on the drug's efficacy.

Drawing of magnified coronavirus particles

Image source: Getty Images.

First introduced in the 1950s to treat malaria, hydroxychloroquine was seen early in the coronavirus outbreak as a potential treatment for COVID-19 following a relatively limited study in France. It was then granted emergency use authorization -- since withdrawn -- by the U.S. Food and Drug Administration (FDA) for certain instances of the disease. President Donald Trump even claimed that he had taken it for preventative purposes.

The results of larger studies, however, indicate that the drug is not effective against COVID-19, and in fact can produce significant fatalities.

The Novartis decision comes less than a week after the World Health Organization (WHO) halted its own hydroxychloroquine COVID-19 study. In the U.S., the National Institutes of Health (NIH) followed suit shortly thereafter.

In the press release on its cessation, Novartis said that it will continue to provide hydroxychloroquine for ongoing studies conducted by both private and public entities "where certain conditions are met and the medicine is used in accordance with a nationally endorsed treatment protocol."

On Monday, Novartis's shares dipped by nearly 0.6%, in contrast to the gains enjoyed by the broader stock market.