The Drug Safety Concern Is That Use Of These Gadolinium Contrast Agents Can Leave Gadolinium Deposits In Brain Tissues
The European Medicines Agency (EMA) recently announced it is taking regulatory action on certain magnetic resonance imaging (MRI) contrast drugs containing gadolinium a couple of months after the U.S. Food and Drug Administration (FDA) decided otherwise.
To understand these divergent paths, we start with the timeline of events giving rise to the EMA's suspension of the MRI drugs Magnevist, Omniscan, and OptiMARK in July 2017.
In March 2017, following its assessment of gadolinium agents used in body scans, the EMA’s Pharmacovigilance Risk Assessment Committee (PRAC) recommended the suspension of certain MRI drugs. This action was based on a review which found evidence of gadolinium deposits in the brain after MRI body scans, but no signs of harm.
According to an April 2017 update to "PRAC concludes assessment of gadolinium agents used in body scans and recommends regulatory actions, including suspension for some marketing authorisations":
Following the PRAC’s March 2017 recommendation, some of the marketing authorisation holders concerned by this referral procedure have requested a re-examination. Upon receipt of the grounds for their requests, the PRAC will start a re-examination, which is expected to conclude in July 2017
Next came this July 7, 2017 EMA document, "PRAC confirms restrictions on the use of linear gadolinium agents", which included this statement: "No specific conditions linked to gadolinium deposition in the brain have been identified, but the clinical consequences are unknown."
Lastly, in its July 21, 2017 document, "EMA’s final opinion confirms restrictions on use of linear gadolinium agents in body scans", we get this further elaboration on that statement:
There is currently no evidence that gadolinium deposition in the brain has caused any harm to patients; however EMA has recommended restrictions for some intravenous linear agents in order to prevent any risks that could potentially be associated with gadolinium brain deposition....
No adverse neurological effects, such as cognitive or movement disorders, have been attributed to gadolinium deposition in the brain with any gadolinium agents.
We turn now to the FDA's treatment of this drug-safety assessment of Magnevist, Omniscan, and OptiMARK, as well as the several other gadolinium-based contrast agents (GBCAs).
From its "FDA Drug Safety Communication: FDA identifies no harmful effects to date with brain retention of gadolinium-based contrast agents for MRIs; review to continue" we get this explanation of why no regulatory action is necessary -- at least not yet:
All GBCAs may be associated with some gadolinium retention in the brain and other body tissues. However, because we identified no evidence to date that gadolinium retention in the brain from any of the GBCAs, including GBCAs associated with higher retention of gadolinium, is harmful, restricting GBCA use is not warranted at this time. We will continue to assess the safety of GBCAs and plan to have a public meeting to discuss this issue in the future....
There are two types of GBCAs based on their chemical structures, linear GBCAs and macrocyclic GBCAs....
The [scientific publications we evaluated] show that linear GBCAs retain more gadolinium in the brain than macrocyclic GBCAs. However, our review did not identify adverse health effects related to this brain retention....
The manufacturer of OptiMARK (gadoversetamide), a linear GBCA, updated its label with information about gadolinium retention in various body organs such as the brain, skin, and other organs. We are reviewing the labels of other GBCAs to determine if changes are needed.
We will be watching for the "public meeting to discuss this issue in the future" mentioned by the FDA -- which, perhaps, will be a so-called Advisory Committee Meeting.
In addition, we will monitor the medical literature for "any risks that could potentially be associated with gadolinium brain deposition" mentioned by the EMA.
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