Also is the government "taking" the drug, or just not extending monopoly patent rights for it? Also even patents (in the US) have a provision that they be reasonable licensed in exchange for gaining the temporary monopoly.
By the United States Constitution, in the United States such a taking must be with compensation (reasonable, market-based compensation). And the same is true in most democratic countries with an independent judiciary. (This is notably not true in China, which is why seizing land from peasants is a favorite way for corrupt local officials to enrich themselves.)
Look, I don't think Bayer will complain at all if India (the country) pays for the drug used by patients in India, like the health systems in UK and Canada. Bayer's complaint is that India doesn't compensate the company.