(Manish Swarup | AP File Photo) In this Thursday, April 9, 2020 file photo, a chemist displays hydroxychloroquine tablets in New Delhi, India. Scientists in Brazil have stopped part of a study of the malaria drug touted as a possible coronavirus treatment after heart rhythm problems developed in one-quarter of people given the higher of two doses being tested. Chloroquine and a similar drug, hydroxychloroquine, have been pushed by President Donald Trump after some early tests suggested the drugs might curb coronavirus entering cells.