Allergan, the US maker of Botox, rejected Monday a takeover bidfrom Valeant Pharmaceuticals, saying it "substantially undervalues" the companyand questioning the Canadian firm's long-term growth plan.Allergan's board of directors unanimously turned down the unsolicited offer fromValeant, worth nearly $46 billion, highlighting its significant risks."After careful review and consideration, our board of directors has unanimouslydetermined that Valeant's unsolicited proposal substantially undervalues Allergan,"said David Pyott, Allergan's chairman and chief executive, in a statement.The proposal "does not reflect the value of the company's leading market positions,sales and marketing foundation, industry-leading research and development efforts,as well as future revenue and earnings growth," he added.In addition, the Irvine, California-based company, best-known for its Botox wrinkletreatment, said it expected earnings per share growth of 20 to 25 percent and continued double-digit sales growth.The Allergan board determined that Valeant's proposal "creates significant risksand uncertainties for Allergan's stockholders and believes that the Valeant businessmodel is not sustainable." On April 22, Valeant Pharmaceuticals, backed by activist shareholder WilliamAckman, proposed a stock-and-cash deal buyout valuing Allergan at $45.6 billion.Valeant said the acquisition would enable huge cost savings and create a leader inopthalmology, dermatology, aesthetics and other growing health fields.Under the terms of the proposal, Valeant would buy each Allergan share for $48.30in cash plus 0.83 shares of Valeant. At the time, Valeant's CEO, J. Michael Pearson,said the proposal represented a "substantial" premium to Allergan's valuation. In rejecting the bid, Allergan, highlighted its large stock component as a risk forAllergan stockholders "due to the uncertainty surrounding Valeant's long-termgrowth prospects and business model.""In particular, we question how Valeant would achieve the level of cost cuts it isproposing without harming the long-term viability and growth trajectory of ourbusiness. For those reasons and others, we do not believe that the Valeant businessmodel is sustainable."Valeant, headquartered in Laval, Quebec, was not immediately available to commenton Allergan's rejection.Allergan shares were down 0.3 percent and Valeant shares shed 0.8 percent inopening trade in New York.