The Food and Drug Administration on Tuesday upgraded a recall of a generic version of blood pressure medication metoprolol to its second-highest level because it failed to meet the FDA’s own criteria.

The recall notice encompasses metoprolol succinate extended-release tablets in 25 milligram doses in 100-count and 500-count bottles. India-based Granules Pharmaceuticals Inc., the manufacturer, voluntarily recalled the medication, which is a beta-blocker used to treat high blood pressure, heart failure, and angina, or chest pain.

Both recalled lots, or roughly 33,000 bottles, have an expiration date of Dec. 31, 2025. They were also distributed throughout the United States, according to the notice.

The FDA said the reason for the recall is that the “product failed to meet dissolution acceptance criteria in the stability studies at the 6th month.”

Granules Pharmaceuticals has not issued a statement on the recall, and the FDA’s notice said that no news release was issued for the action. The Epoch Times contacted the company for comment.

“Our investigators observed significant contamination in multiple ducts … used in the preparation of finished drug products manufactured at your facility,” the FDA’s letter said, in part. “While filters were installed to prevent contamination, inadequate cleaning and maintenance processes rendered them ineffective.”

It added that elsewhere, “bird droppings and feathers were observed during the inspection” in the factory’s air handling unit, among other alleged violations.

“Your response is inadequate. Cross-contamination is not uniform, and testing of limited reserve samples alone cannot ensure products are contaminant-free,” the February letter further said. “Immediate remediation, effective cleaning protocols, and comprehensive testing are essential to resolve this serious [current good manufacturing practice] violation.”