Police have arrested the owners of two local pharmaceutical firms that supplied the drugs to the government-owned Punjab Institute of Cardiology.
Neither of the two firms have commented on the allegations.
Doctors believe one or more of at least four drugs given to patients at the institute directly led to their deaths.
The drugs were purchased at competitive rates and were allegedly offered to patients free of cost.
“More than 100 patients brought to various hospitals in Lahore for suspected drug reactions have all been recently under treatment at Punjab Institute of Cardiology, and were given these drugs,” Punjab provincial Health Secretary Jehanzeb Khan said on Monday.
Hospital sources told BBC if they do not buy drugs from the lowest bidder, they can be taken to court by local pharmaceutical companies and even be issued with an injunction against all future purchases