Hospira, the leading manufacturer of injectable drugs, has been a major target of quality complaints. Since 2009, federal regulators have outlined failures in quality control at its plants in North Carolina, California and Costa Rica, leading to several major recalls of products as diverse as faulty infusion pumps and overfilled morphine vials. The company has slowed production at its largest factory in Rocky Mount, N.C., which had the most extensive problems.

Hospira’s manufacturing issues became public months after the company began in 2009 a two-year initiative called Project Fuel, designed to save more than $100 million a year by, for example, shrinking the work force 10 percent.

Critics, including a group of shareholders who have filed a lawsuit against Hospira, claim that Project Fuel led to deep cuts in quality control, including the dismissal of seasoned employees and the failure to maintain equipment. In comments to investors last year, a Hospira executive acknowledged the company had gotten “a little lazy” and was “skating behind the puck.”

Stacey Eisen, a Hospira spokeswoman, said the company supported the F.D.A.’s recent focus on manufacturing quality. “We support the agency in this respect, as we, too, consider the quality of our products to be of paramount importance, and we’re working closely with the agency on all aspects of our quality efforts,” Ms. Eisen said. She said Project Fuel was not about cost-cutting but about reducing complexity across the company and improving productivity.

Late last year, Ben Venue, a division of the German drug maker Boehringer Ingelheim, shut its plant in Bedford, Ohio, after the F.D.A. visited the facility. Agency inspectors reported rusty tools, mold and a barrel of an “unknown liquid” later determined to be urine; the report did not make it clear what the barrel was doing there. Three other companies that make injectable drugs — Sandoz, Luitpold Pharmaceuticals and A.P.P. Pharmaceuticals — have also received warning letters. Earlier this year, Sandoz slowed production at a plant in Quebec to fix problems identified by the agency. All the companies said they took quality seriously and were either working with the agency to address its concerns or had already resolved the issues.

In a particularly vivid lapse, agency inspectors cited the failure to investigate a number of reported problems at A.P.P.’s plant outside of Buffalo, including complaints of human hair and fungal growth in vials.

One former supervisor at the plant said his managers were reluctant to stop the production lines. “It’s like trying to fix your car when you’re driving down the Thruway,” said the former employee, who was recently terminated and said he did not want to be identified because he feared retaliation. Managers ordered shortcuts that compromised quality, he said, and skimped on cleaning to shorten the turnaround time between batches. Afterward, centipedes and spiders were spotted in manufacturing areas, he said.