Details of the recall were made public by the Spanish Agency of Medicines and Medical Devices (AEMPS) late last week (here in Spanish).
The Madrid-based regulatory organisation said the Kogenate recall was prompted by the detection of out of specification results during stability studies.
This was confirmed by Bayer spokesman Kilian Guasch Tellez who told us: "During routine product testing, stability data for specific lots of Kogenate FS/Bayer indicated that the product’s potency was declining during its shelf life at a greater pace than normal.
"As patient safety is our highest priority we are voluntarily recalling lots below potency specification and lots that currently meet the potency requirements but have been identified as being at risk of falling below specification prior to shelf life expiry.
He added that: "Based on data that have been reviewed so far for Kogenate FS/Bayer, no safety observations or signals have been detected by Bayer’s drug safety group which would be indicative of a low potency type product issue.
"We are working closely with regulatory authorities to ensure an efficient recall process that minimizes any disruption to supply and inconvenience to patients."
Kogenate is a recombinant factor VIII (rFVIII), which is a blood-clotting recombinant protein that is an alternative to Factor VIII derived from donated plasma. It is used for the prophylactic treatment of haemophilia.
The affected Kogenate lots were made at Bayer's production plant in Berkley, US.
In 2015, Bayer announced it would create a $100m (€94m) product testing suite at the facility.