Bayer and Guerbet Advance Long-Term Gadolinium Safety Study, Keeping MRI Contrast Risk in Focus

Bayer AG (BAYRY), Guerbet SA (GUERF) announced an update on their ongoing clinical study.

Study Overview: This ongoing Phase 4 study, officially titled “Prospective Evaluation of Potential Effects of Repeated Gadolinium-based Contrast Agent (GBCA) Administrations of the Same GBCA on Motor and Cognitive Functions in Neurologically Normal Adults in Comparison to a Non-GBCA Exposed Control Group,” is designed to see whether repeated use of gadolinium-based contrast media over five years affects body movement or mental skills in adults up to age 65. The project is significant because it addresses long-term safety questions around widely used MRI contrast agents, an issue that can influence both clinical practice and the commercial outlook for the imaging portfolios of Bayer AG, Guerbet, and other partners.

Intervention/Treatment: The study compares three groups: patients receiving “linear” gadolinium agents such as Eovist/Primovist (gadoxetate disodium), MultiHance (gadobenate dimeglumine), or Omniscan (gadodiamide); patients receiving “macrocyclic” agents such as Gadavist/Gadovist (gadobutrol), Dotarem/Magnescope (gadoterate meglumine), or ProHance (gadoteridol); and a control group that does not receive any gadolinium contrast. All participants undergo regular movement tests, memory and thinking tests, brain scans without contrast, and measurements of gadolinium in blood and urine to track any changes over time.

Study Design: This is an interventional, non-randomized, parallel-group Phase 4 study, meaning participants are placed into one of the three groups based on their clinical imaging needs rather than by random assignment. There is no blinding, so both doctors and patients know which contrast type, if any, is used. The main purpose is not to test effectiveness of the drugs, but to monitor long-term safety and understand whether repeated exposure leads to noticeable changes in movement or mental performance compared with people who never receive these agents.

Study Timeline: The study was first submitted on April 30, 2020, marking the formal start of regulatory and operational setup. It is designed to follow participants over five years with at least seven study visits, so primary completion will align with the end of this follow-up window once full enrollment is achieved. Final completion, when all data are collected and analyzed, is expected after that five-year window closes. The record was most recently updated on January 21, 2026, confirming that the protocol and status remain current and that recruitment is still active.

Market Implications: For Bayer (BAYRY), Guerbet (GUERF), and peers Bracco and GE Healthcare, this safety study is strategically important. Clear evidence that repeated gadolinium use does not harm movement or mental function would support continued use of their contrast products, reduce regulatory risk, and help defend pricing in a mature but essential imaging market. Any sign of safety concerns, especially with older “linear” agents, could accelerate the shift toward “macrocyclic” products, reshaping market shares within the group rather than collapsing overall demand. In the near term, the updated recruiting status and fresh 2026 filing signal active risk management and regulatory engagement, which should be modestly reassuring for investors focused on litigation and safety overhangs in diagnostic imaging. Sector peers in medical imaging and radiology equipment may also benefit from a stable safety profile, as it underpins ongoing MRI procedure volumes.

The study remains ongoing and recently updated, with further details available on the ClinicalTrials portal.

To learn more about BAYRY’s potential, visit the Bayer AG drug pipeline page.