GlaxoSmithKline and rivals including Pfizer are preparing second-round bids for Turkey's Mustafa Nevzat Ilac Sanayi, a maker of injectable generic drugs, that may be worth as much as $800 million, four people familiar with the process said.

The keen interest in the Istanbul-based business, also known as MN Pharmaceuticals, underscores the race by Western drugmakers to expand in emerging markets, where sales are growing much faster than in Europe and the United States.

The family owners of MN Pharmaceuticals have hired Bank of America Merrill Lynch as adviser. Two sources said the owners would prefer to sell a minority stake, if the price was high enough, but that Western firms would like full control.

Other international pharmaceutical companies that have eyed the business include Fresenius, Merck & Co., Mylan, Abbott and Amgen. However, no more than five will be short-listed for the auction's second stage.

Two people said Mylan, Abbott and Amgen might have already dropped out.

The international companies involved declined to comment, while a representative for MN Pharmaceuticals said no one was available to speak on the matter. A decision could come around the end of April.