LONDON: AstraZeneca said U.S. regulators would not approve its new drug for high potassium levels at present due to a manufacturing issue, dealing a blow to a product acquired when it bought ZS Pharma for $2.7 billion last year.

The British drugmaker said the Food and Drug Administration (FDA) had issued a so-called complete response letter (CRL) for ZS-9, or sodium zirconium cyclosilicate.

Such letters typically outline concerns and conditions that must be addressed to gain U.S. approval.

"The CRL refers to observations arising from a pre-approval manufacturing inspection," AstraZeneca said. "The FDA also acknowledged receipt of recently submitted data which it has yet to review. The CRL does not require the generation of new clinical data."

A spokesman said the company hoped to resolve the matter in a "timely" manner.