The Anglo-Swedish drug manufacturer reported the complete response letter (CRL) last week, explaining it followed an inspection at Zs Pharma's facility in Coppell, Texas.
An AstraZeneca spokesman told us "As part of the FDA review, an inspection took place at the ZS-9 manufacturing site in Texas, earlier in 2017. The subsequent CRL is a result of that inspection."
The CRL is the second AstraZeneca has received for the drug.
He added that: "While we are disappointed with the news of a second CRL, our team is fully committed to meeting quickly with the FDA to discuss the open items and work closely with the Agency to resolve them. At this time we cannot provide more details on timing."
AstraZeneca stressed the US Food and Drug Administration (FDA) had not asked for more clinical trial data.
AstraZeneca received the first CRL last May after a pre-approval inspection of the Coppell facility.
According to an initial public offering (IPO) Zs Pharma filed in 2014 – a year before it was acquired by AstraZeneca – Zs-9 (sodium zirconium cyclosilicate) is made at two company-owned facilities.
In addition to the Coppell manufacturing site, Zs Pharma has a facility in Denver, Colorado.
The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) recommended that Zs-9 – under the name Lokelma - be approved in February.