GUWAHATI: A senior anaesthetist at a private hospital in Guwahati who was on hydroxychloroquine to protect Covid-19 infection — as are many other doctors elsewhere in the country — died of a heart attack here on Sunday afternoon after posting a message to colleagues on a WhatsApp group saying he thought he was having "some problems" after taking the medicine.There was, however, no way of knowing immediately whether his death was a direct consequence of using the drug. "Without a post-mortem one cannot explain Barman’s death," Guwahati-based internal medicine specialist Swarup Jyoti Saikia said, adding that the death did, however, raise "a red flag". Doctors said they would investigate the matter thoroughly.Utpaljit Barman (44), who headed the anaesthetics team at Pratiksha Hospital, had sent a message to colleagues in a WhatsApp group about half an hour after suffering the heart attack at home saying, "HCQS (hydroxychloroquine) is not good as prophylaxis (action taken to prevent disease). Lots of issues. I think I am having some problems after I took it."The anti-malaria drug is commonly used to treat rheumatoid arthritis.Pratiksha Hospital medical superintendent Nirmal Hazarika said, "He took it… not just him, other doctors in our hospital are also taking hydroxychloroquine as a preventive measure. The signs of symptoms at the time of his death were that of a heart attack." He, however, added that hospital authorities are not yet issuing any instructions to doctors to discontinue the drug."He suffered the attack at his home at around 2.30 pm and was taken to the hospital where he died after about one and a half hours," Hazarika said.Two hydroxychloroquine tablets of 200 mg have to be taken every seven days and Dr Barman had taken his last dose on March 22."The attack should not have happened in a person with a healthy heart. This drug is one of the safest among all the drugs used for treatment of rheumatoid arthritis and is now also prescribed for some cases of uncontrolled diabetes," Guwahati-based internal medicine specialist Swarup Jyoti Saikia said.He added, "After the ICMR issued an advisory, there has been mass use of this drug among doctors. When there are inadequate number of PPEs, this drug becomes the immediate protection for all frontline healthcare workers. We have to be cautious now."Saikia added, "I have received reports from the US that three patients had sudden cardiac deaths after receiving hydroxychloroquine and azithromycin in California a couple of days ago."The National Task Force for Covid-19, constituted by the ICMR, has recommended the use of hydroxychloroquine for prophylaxis of SARS-CoV-2 infection for high-risk populations. The advisory provides for "placing the following high-risk population under chemoprophylaxis with hydroxychloroquine: Asymptomatic healthcare workers involved in the care of suspected or confirmed cases of Covid-19 and asymptomatic household contacts of laboratory confirmed cases."The protocol recommended by the National Task Force has been approved by the Drug Controller General of India for restricted use in emergency situations.