Generic drug company Mylan has raised its bid for a second time for Perrigo, offering $35.6 billion for the over-the-counter giant.
The offer was swiftly rejected by Dublin-based Perrigo, however.
Perrigo's rejection further intensifies a three-way battle to gain a bigger share of the generic drugs market as more leading drugs lose patent protection.
Mylan, which itself is fending off a takeover bid from generics giant Teva, offered $75 in cash and 2.3 Mylan shares for each Perrigo share.
A Mylan-Perrigo tie-up would create a company with more than $15bn in annual sales and generate $800m in annual savings from operational synergies, according to Mylan.
Perrigo completed a takeover of Irish pharmaceutical firm Elan in late 2013, in a deal which saw it move its headquarters to Dublin.
Mylan chief executive officer Heather Bresch said a combination between with Perrigo would create "a one-of-a-kind global healthcare company" with "complementary businesses and cultures, unmatched scale in its operations and infrastructure, broad and diverse portfolio, and immense reach across distribution channels around the world."
But Perrigo has shown no appetite for such a deal so far, rejecting the prior two bids and saying they undervalue the company.
Mylan's unsolicited offers to Perrigo come as it fights a comparable campaign launched by Israeli giant Teva to buy Mylan and build a global behemoth in generic drugs.
On Monday, Mylan dismissed Teva's $40.1bn offer as both "grossly" low and insincere, "a mere attempt by Teva to frustrate and distract Mylan from its business plan and strategy."
