(Adds details about R&D facility closing, bylines)
By Tamara Mathias and Ahmed Farhatha
Jan 9 (Reuters) - U.S. drugmaker Pfizer Inc said on Wednesday it was shutting down two manufacturing plants in India that make generic injectables like penicillin in response to falling demand.
The company employs around 1,700 workers at the two factories in the states of Tamil Nadu and Maharashtra - nearly 6 percent of Pfizer's global manufacturing workforce.
"Pfizer has conducted a thorough evaluation of the ... sites in India and concluded that due to the very significant long term loss of product demand, manufacturing at these sites is not viable," the company said in an emailed statement.
Pfizer acquired the sites as part of its $15 billion purchase of Hospira Inc in 2015, to boost its portfolio of generic injectable drugs and copies of biotech medicines.
The company is also closing a Hospira research and development lab in Taramani, Chennai, but spokesman Steven Danehy said that was unrelated to the shutdown of the two plants.
The roughly 150 employees at that facility were informed of that shutdown in the fourth quarter, he said.
The plant in Chennai makes generic injectable cephalosporin, penems and penicillin. The Maharashtra plant supplied the Chennai unit with certain products.
Both plants do not manufacture products for the India market, Pfizer said, adding that it is expanding operations in its Visakhapatnam facility in south India.
Indian financial newspaper Business Standard first reported here the news of the manufacturing plant closings on Tuesday.
Reporting by Tamara Mathias and Ahmed Farhata in Bengaluru; Editing by Arun Koyyur and Richard Chang