Another fluorinated drug banned

News about fluorinated drugs
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Another fluorinated drug banned

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NOTE: The active ingredient of Prexige is lumiracoxib. The chemical name is {2-[(2-chloro-6-fluorophenyl)amino]-5-methylphenyl}
acetic acid.

Another painkiller pulled off shelves

Prexige; Drug 'cannot be safely managed': Health Canada

National Post - October 05, 2007

By Tom Blackwell

Months after it hit the market as an "effective and safe" medication, the latest in the troubled Cox-2 class of painkillers was pulled yesterday by Health Canada, amid evidence Prexige can cause serious liver disease in some patients.

The regulator took action partly because of strong suspicions the medication made two Canadians seriously ill with a form of
hepatitis, one of them days after starting to take the drug.

The news comes three years after Vioxx, another hugely popular Cox-2, was withdrawn because of evidence it caused heart attacks and strokes, creating the biggest drug-safety controversy since the Thalidomide scare of the 1960s.

A third medication in the class, Bextra, was later pulled off the market after being linked to potentially fatal skin ailments.

Australian authorities stopped sales of Prexige in August when eight patients taking the drug at doses of 200 and 400 milligrams developed serious liver problems. Two of those patients died. Four other patients, including two in Canada, have come down with similar complications while on the 100-mg pill approved here.

"The risk of serious liver-related adverse events with Prexige cannot be safely and effectively managed at the 100 mg daily dose," Health Canada said yesterday.

News of the ban, though, was met with mixed reaction from outside experts. Some applauded the regulator for taking firm action and even questioned why Prexige was initially approved last year. Others called it a knee-jerk reaction to side effects that Health Canada admits occur rarely.

In fact, many other nonsteroidal anti-inflammatory (NSAID) painkillers that have been on the market for years can cause the same type of liver reaction, a risk that patients should be free to weigh for themselves, said Dr. Walter Maksymowych, an Edmonton rheumatologist and professor at the University of Alberta.

"Very soon we're going to be treating patients with a mortar and pestle, if this continues," he said.

"It's going to be very difficult for any drug manufacturer to put any drug out there because of the concern that maybe patients will develop a serious adverse reaction."

Novartis Pharmaceuticals, which makes the medication, stressed in a news release yesterday that pre-market trials showed Prexige caused fewer gastrointestinal problems than competing NSAIDs, and no more cardiovascular events.

There was evidence, however, of an increased risk of cardio side effects, at least compared with naproxen, argues Dr. James Wright, a pharmacology professor at the University of British Columbia. He praised Health Canada for taking action now, but said it should not have been approved in the first place. "I had major concerns about this drug."

Just last week, meanwhile, the U.S. Food and Drug Administration decided not to approve Prexige, which is still on the market in Europe and elsewhere.

Ihor Susko, a former college soccer player with arthritis of the knee, received a call from his pharmacist yesterday morning telling him the drug had been recalled.

It was a familiar routine: The 63-year-old Toronto resident was on Vioxx when it was withdrawn, too. "It becomes a hassle," said Ina, his wife.

Introduced less than a decade ago, the Cox-2 inhibitor class turned into one of the world's best-selling group of pharmaceuticals, offering the painkilling benefits of traditional NSAIDs with less of the ulcers and other gastrointestinal side effects.

Then, in late 2004, Merck was pulled from the market, followed by Bextra, putting a cloud over the Cox-2 class, though Celebrex remains a strong seller to this day. Government advisory bodies here and in the United States later concluded that Cox-2s did increase the risk of cardiovascular problems slightly, but, with the exception of Vioxx, no more than other
NSAIDs, such as ASA and ibuprofen, that had been on the market for decades.

Prexige went on sale in Canada last November, initially as a treatment for arthritis of the knee. When Health Canada extended its use to all forms of osteoarthritis in July, the company's PR firm hailed the drug as an "effective and safe option."

More than 200,000 prescriptions of it, worth $10-million, have been dispensed since September, 2006, according to IMS Health Canada, which provides information on the health care field.

Nothing in Novartis's extensive pre-market trials suggested it might trigger liver toxicity, said Dr. Marc Berthiaume, head of the department's marketed pharmaceuticals bureau.

Suspicions emerged, though, once the drug hit the market and started to be used more widely. Even before the Australian news, the regulator had begun to look closely at Prexige because of evidence of heightened liver enzyme levels in patients, an indicator sometimes of potential liver toxicity, he said. The two Canadians who developed hepatitis were hospitalized but have been taken off the drug and are recovering. Although the cause of their illness is not certain, it is considered "probable" that Prexige was to blame, Dr. Berthiaume said.

The risk of such adverse events among patients on the drug is rated between rare -- no more than one in 1,000 -- and very rare -- less than one in 10,000, he said.

Given that other, similar drugs are available, Health Canada felt the risks were too great to tolerate, Dr. Berthiaume said.

That would appear to be the right decision, said Dr. Andreas Laupacis of Toronto's St. Michael's Hospital, head of the advisory committee that reported to the government on Cox-2s.

"Given there are a lot of drugs on the market ... for people with arthritis, one does err on the side of caution."

SOURCE:
http://www.canada.com/nationalpost/news ... f5&k=60355
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