Merck is implementing an aggressive price control plan for cholesterol treatment Zocor (simvastatin) to hang on to market share following the drug’s loss of patent protection Friday.A spokesman from health insurer UnitedHealth Group told The Wall Street Journal his firm had negotiated reduced prices for Zocor with Merck and would move its branded drug into its cheapest tier on its three-tier formulary.The move is expected to reduce the co-payment for Zocor made by patients at pharmacies to $10 from $25. The FDA wasted no time in approving two generic versions of Zocor on Friday as the Zocor patent expired.Earlier this week, Senator Chuck Schumer, a Democrat from New York also charged that Merck was quietly collaborating with health insurance companies to create lower copays for customers buying Zocor than for those buying the generic version. Schumer said he has asked the Federal Trade Commission to investigate the matter. In response to the Schumer allegations, a Merck spokesman, told the Associated Press, “We support generic competition and the generic competition for is good for patients… We are going to continue to price it (Zocor) competitively.”