Reports: Elan not responding to acquisition offer from Royalty Pharma

NEW YORK — A privately owned drug maker in New York is offering $6.5 billion for Irish drug maker Elan, but hasn't heard back from it, according to published reports.

The Associated Press reported that Royalty Pharma's $11-per-share offer for Elan represented a 4% premium over its closing price Friday. Royalty buys royalty interests in drug products that are in late-stage development or have already entered the market, but doesn't develop or market drugs of its own, the AP reported.

Earlier this month, Elan announced that it would sell rights to the multiple sclerosis drug Tysabri (natalizumab) to partnering company Biogen Idec for $3.25 billion plus royalties.