> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# AstraZeneca Gets 2nd Complete Response on ZS-9
- URL: https://www.fdaweb.com/astrazeneca-gets-2nd-complete-response-on-zs-9/
- Published: 2017-03-17T12:00:00.000Z
- Updated: 2026-09-14T22:12:20.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5138226

FDA has issued AstraZeneca a second complete response letter (CRL) on its NDA for ZS-9 (sodium zirconium cyclosilicate), indicated for treating hyperkalemia (high potassium level in the blood serum). A CRL was issued 5/2016 that identified observations during a pre-approval manufacturing inspection. The agency did not request any new data, AstraZeneca said at the time. The latest CRL followed an inspection by FDA of the ZS-9 manufacturing facility, according to the company, and it does not require the generation of any new clinical data.

  
ZS-9 is an insoluble, non-absorbed zirconium silicate with a three-dimensional crystalline lattice structure that was designed to preferentially trap potassium ions, AstraZeneca says. “The unique potassium selectivity of ZS-9 enables high in-vitro binding capacity for potassium ions even in the presence of other competing ions,” it says. The therapy has been studied in three double-blind, placebo-controlled trials, and in two ongoing 12-month open label studies in over 1,600 patients.