The latest leaked document on the Trans-Pacific Partnership further indicates the Government's drug-buying agency is under threat, the Green Party says.
The United States-based political website, Politico, has obtained a draft copy of the trade agreement's intellectual property chapter, dated from May.
The leaked text shows the Trans-Pacific Partnership would give American pharmaceutical firms unprecedented protections against competition from cheaper generic drugs.
Greens' co-leader James Shaw said it was the second leaked document in the past month showing the agreement could severely erode Pharmac's ability to buy affordable drugs.
"What it really means is that New Zealanders will end up paying a great deal more for their medicines than they are currently able to."
Mr Shaw said the Government needed to lift the lid on the secrecy surrounding the deal.