In order to reduce its tax bill, OTC drug maker Perrigo has agreed to acquire Ireland-based Elan for approximately US$8.6 B, or US$6.7 B net of cash on hand. Elan’s principal asset is a tiered double-digit royalty stream on sales of the multiple sclerosis drug Tysabri® (natalizumab), which it sold to its former partner Biogen Idec in April 2013. The deal ends months of takeover speculation for Elan, which put itself up for sale in an attempt to thwart a hostile takeover bid from investment firm Royalty Pharma.