The FDA sent AstraZeneca’s ZS Pharma a second complete response letter rejecting the company’s drug candidate to treat high potassium.

The CRL followed an FDA inspection of the manufacturing facility used to produce the candidate called ZS-9, the company said.

The letter focused on the validation of the manufacturing process, an AstraZeneca spokeswoman said.

AstraZeneca said it will work with the FDA to resolve the issues raised in the latest CRL as soon as possible. The company received a previous CRL from the agency in May 2016.