"The company still has a presence in Puerto Rico," he said. "We've been here for 65 years."
Merck currently operates three plants on the island and employs more than 1,000 workers.
Antonio Medina, a former Merck official and executive director of Puerto Rico's Industrial Development Company, said in a phone interview that he believes the investment at the Las Piedras plant will help boost Puerto Rico's economy.
"This is part of the evolution of the pharmaceutical world," he said of the upcoming layoffs and restructuring.
Back in 2009, Merck had announced a $65 million expansion and the construction of a new plant in Barceloneta that would employ more than 200 people. Since then, the island's pharmaceutical industry has declined.
Honorio Saavedra, executive assistant of Barceloneta's mayor, said the city has tried to diversify its economy to deal with the downturn.
"This will have some impact," he said. "Those employees will now depend on the government."