A key part of the trade deal between the U.S., Mexico, and Canada gives brand name pharmaceutical manufacturers a longer monopoly on sales of pricey specialty drugs called biologics.

The proposed deal between Canada and the U.S. announced on Monday increases the market exclusivity for biologic drugs, which are tissue-based drugs like vaccines, to 10 years for products sold in Canada. A deal between Mexico and the U.S. negotiated announced in August also had the increase to 10 years.

The generic drug lobby group called Association for Accessible Medicines said that the trade deal would “provide a windfall for brand-name drug manufacturers and raise prescription drug prices for patients in the United States.”

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Competition for biosimilar drugs, which are cheaper drugs that are similar to biologics, would be stifled as a result of the deal, the group added.

Currently, in the U.S., a brand name drugmaker has exclusivity of 12 years for a biologic drug.

In Canada, biologic drugs currently have exclusivity of eight years, and in Mexico, five years. During these exclusivity periods, a competitor who wants to sell a biosimilar cannot market their product.