ADVIA 1200 Chemistry System, Automated Clinical Chemistry Analyzer - human serum, plasma and urine tests. The following are the measured parameters that are within the scope of this ''field correction'': Affected assay: Valproic Acid. Affecting assays: Digoxin; Phenytoin; Gentamicin; Theophylline.

Bayer received a customer complaint where the Valproic Acid Quality control material recovered lower than target when it was run in a panel of other Therapeutic Drug (TDM) assays. The under recovery observed by the customer was approximately -25%.

On 9/08/06, a Support Bulletin was sent to all affected Bayer HealthCare LLC Branches in order to inform them of the issue and to provide them with instructions for the 'field correction'. On 9/08/06, a Customer Bulletin was sent to all affected Bayer HealthCare LLC Branches both in the US and worldwide for communication with the affected end user customers. The bulletin advises of the problem and the corrective action. A Completion Confirmation (Fax-back) Form was included to ensure that all customers worldwide have been notified and have complied with the mandatory action. The Customer Bulletin is to be sent to all affected end user customers. Bayer Technical Service Specialists will follow-up with all of the ADVIA Chemistry System customers to make sure they have understood the bulletin and to ask that they return the FAX-back Completion Confirmation Form to Bayer HealthCare. If Bayer HealthCare does not receive the form in a timely manner, specialists in the Bayer Technical Care Center will contact the customer through whatever means possible in an effort to obtain 100% effectiveness on this communication.