* FDA staff: Higher strength raises overdose concern
* Advisory panel reviews gadobutrol on Friday
* Bayer shares down 0.3 percent (Adds details, share move, byline)
By Lisa Richwine
WASHINGTON, Jan 19 (Reuters) - U.S. advisers will be asked to focus on the potential for overdoses and a serious skin disorder when they review a Bayer AG (BAYGn.DE) imaging drug on Friday.
Food and Drug Administration staff, in documents released on Wednesday, said they wanted input from the panel of outside experts on risks of nephrogenic systemic fibrosis (NSF), a potentially fatal skin disorder seen with similar drugs.
Bayer’s product, gadobutrol, is a stronger version of products in a class called gadolinium-based contrast agents, or GBCAs, used with magnetic resonance imaging scans.
“Because the risk for NSF has been associated with higher GBCA doses, the potential for gadobutrol overdosage errors has implications for assessing the agent’s NSF risks,” FDA staff wrote in a summary prepared for the advisory panel.
The company is seeking FDA approval to sell gadobutrol for use with MRIs of the central nervous system. Five other drugs already are approved for that use at half the strength of gadobutrol.
In September, the FDA ordered new warnings on GBCAs about NSF risk in patients with kidney disease. Bayer’s Magnevist, Covidien’s COV.N Optimark and Omniscan, made by General Electric’s (GE.N) healthcare division, were identified as having a higher risk than other approved GBCAs.
Bayer has reported 10 cases of NSF since gadobutrol was approved in Europe in 1998, the FDA staff said. Two patients received only gadobutrol while others also were given other GBCAs. About 5 million patients have been exposed to gadobutrol, which is sold under the name Gadovist.
Preliminary findings suggest gadobutrol’s NSF risk is “similar to ‘lower’ NSF risk agents,” FDA staff said. The agency reviewers also said the drug appeared effective.
Bayer, in a summary also released by the FDA, said it would prominently display the higher strength on gadobutrol’s label to help prevent overdoses.
The company “welcomes the opportunity to participate in a scientific discussion about the data that support our application,” Bayer spokeswoman Marcy Funk said. The drug is approved in more than 60 countries.
The company’s shares were down 0.3 percent in German trading.
The FDA posted the summaries from Bayer and FDA staff at link.reuters.com/qem27r. (Reporting by Lisa Richwine, editing by Dave Zimmerman)