Three of the four patients in the state have now been declared coronavirus-free.
Singh said the first two patients tested positive for the virus were an Italian couple.
"Their symptoms were flu-like so they were initially given anti-malaria and anti-swine flu drugs," he said.
"All this while, our doctors were in touch with the Indian Council of Medical Research and the Drug Controller General of India. Since the structure of coronavirus is similar to that of HIV to some extent, so they tried a combination of the two anti-HIV drugs," he added.
"It appears it (combination of drugs) is working because three patients have recovered. Good thing is that all the three patients are elderly and the successful result of the drug on patients of such age is a big thing," he said.
Dr D S Meena, Superintendent of the SMS Hospital, where all the three patients were treated, said the combination of the anti-HIV drugs proved useful in treating the patients.