A heated dispute within the Food and Drug Administation on whether to put new lung-cancer warnings on leading blood-pressure drugs taken by millions of people is unlikely to have any significant effect on either the stocks of the drugs' manufacturers or their future sales, analysts said Friday.
The fight within the FDA, reported by The Wall Street Journal Friday, detailed how Thomas Marciniak—a senior regulator at the agency—had without success demanded that the FDA inform doctors and patients about the purported lung-cancer risks from blood-pressure drugs known as angiotensin receptor blockers.
Sales of ARBs—which include Diovan by Novartis; Avapro by both Sanofi and Bristol-Meyers Squibb; Cozaar by Merck & Co; and Micardis by Boehringer Ingleheim—topped $7.6 billion last year. Shares of the drug makers were trading lower Friday as the Dow tumbled more than 200 points.
"The FDA must act now," Marciniak wrote senior FDA officials, noting he had found raw data from patients in drug studies showing a 24 percent increase in the risk of lung cancer compared to patients taking placebos or other drugs, the Journal reported.
But the FDA refused to modify a finding first issued in 2011, which ruled there was no such increased risk of cancer from ARBs. FDA officials disputed Marciniak's methodology for analyzing that risk.
Analysts who follow the drug companies said the FDA's official position remains that there is no cancer risk from the so-called ARB drugs—a point the agency has confirmed—and that overall revenue from sales of those drugs are already declining as they have gone or head off-patent.
"Even if the drugs were pulled off the market, it would have virtually no impact on the brand companies," said Corey Davis, managing director for equity research of specialty pharmaceuticals at Jeffries & Co.
Jefferies' Davis said he was skeptical about Marciniak's findings and about the need to slap a new warning on the ARBs.
"Given the level of scrutiny over this type of stuff, I can't believe that one guy found something that an army of researchers and officials have been looking for for years, and missed," Davis said.
"If there was a cancer signal it would have come up a long time ago," said Davis, noting that "there's millions of people taking these drugs."
Judson Clark, who analyzes pharmaceutical companies for Edward Jones, said, "In all cases, [ARBs] are shrinking in terms of sales," which reduces the potential negative effect to an individual company's bottom line from a new warning.
"It's just not a situation where these are big growth drivers for the companies," Judson said. "I think the practical effect will be negligible."
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Tony Butler, who analyzes Merck and Bristol-Meyers Squibb for Barclays, echoed that, noting that many of "these drugs are off-patent"—or on their way there—reducing their value to their manufacturers.
"I would suggest that there's not a likelihood that there would be any effect on sales because these drugs are off-patent," Butler said. He added, "I take one of these drugs, and I don't think I'm going to have an increased risk of lung cancer."
Butler also said it was possible that Marciniak's warning could actually cause more harm because patients may stop taking their medication. "[If] you made a big enough deal about it, people would pick up the press and somebody would say, 'My drug causes cancer,' and then they had a heart attack six months later.' Then what did you do?"
In response to a CNBC query, FDA spokeswoman Sandy Walsh said, "Our position on ARB drugs has not changed. Our recommendations and findings from our 2011 drug safety communication still stand. Based on our review of all available data the FDA concluded that treatment with ARB medication does not increase the risk of cancer."
"These are important medications for many people. People taking ARB medications should not stop taking their medication and should discuss any questions or concerns with their health care professional," she said.
"The FDA respects and recognizes that scientific differences occur and we listen to all voices," she added. "The agency has procedures in place to manage internal disputes and we will follow those."
—By CNBC's Dan Mangan