Delhi Police on Friday said it has arrested four men over the past three days involved in the black marketing of COVID-19 drug Remdesivir and recovered 81 vials from the accused. "They have a set network of persons who supply the injections on demand. They were selling Remdesivir injections for ₹25,000 to ₹40,000 per vial," DCP (Crime) Monika Bhardwaj said.