The Federal Trade Commission voted Tuesday to block mergers involving the nation's four largest drug wholesale companies.

According to the FTC, the mergers would give the companies 80 percent of the $80 billion drug industry and could drive prices up 1 percent, or $800 million."That means higher prices for prescription drugs and a reduction in the timely delivery of these drugs to hospitals, nursing homes and drugstores, which could affect patient care," said William J. Baer, director of the FTC's Bureau of Competition.

Recent deals among the nation's top four drug wholesalers, including one plan by the biggest distributor to buy a top rival, would leave two companies handling more than half of the nation's prescription drug sales.

San Francisco-based McKesson Corp., the No. 1 drug distributor, said in September it agreed to buy No. 4 AmeriSource Health Corp., based in Malvern, Pa., for $1.75 billion worth of stock. No. 2 Cardinal Health Inc., headquartered in Dublin, Ohio, is in the process of buying No. 3 Bergen Brunswig Corp. of Orange, Calif., for $2.62 billion.

McKesson has said the deal would swell its profits and could lead to lower prices for consumers, and is expected to challenge the FTC ruling in court.