The U.S. Food and Drug Administration has rejected the new drug application of AstraZeneca’s hyperkalemia drug sodium zirconium cyclosilicate (ZS-9) due to observations arising from a pre-approval manufacturing inspection, AstraZeneca announced May 27. The FDA issued AstraZeneca a complete response letter (CRL) and acknowledged receipt of recently-submitted data which it has yet to review. The CRL does not require the generation of new clinical data, according to AstraZeneca. The company said it is evaluating the content of the CRL and will work closely with the FDA to determine the appropriate next steps for the NDA.

“AstraZeneca remains committed to the development of sodium zirconium cyclosilicate as a treatment option for patients with hyperkalaemia,” the company said in a statement. “Interactions are ongoing with other health authorities in the European Union and Australia, where sodium zirconium cyclosilicate is currently under separate regulatory review.”

Last year AstraZeneca bought ZS Pharma for $2.7 billion to gain access to the drug.