Posts Tagged ‘COX-2 inhibitors’

Side effects and withdrawal

Saturday, December 13th, 2008

On April 7, 2005, Pfizer withdrew Bextra from the U.S. market on recommendation by the FDA, citing an increased risk of heart attack and stroke and also the risk of a serious, sometimes fatal, skin reaction. This was a result of recent attention to prescription NSAIDs, such as Merck’s Vioxx. Other reported side-effects were angina and Stevens-Johnson syndrome.

Pfizer first acknowledged cardiovascular risks associated with Bextra in October 2004. The American Heart Association soon after was presented with a report indicating patients using Bextra while recovering from heart surgery were 2.19 times more likely to suffer a stroke or heart attack than those taking placebos.

Recently in a large study published in JAMA 2006, valdecoxib appears less adverse for renal (kidney) disease and heart arrhythmia compared to Vioxx, however elevated renal risks were slightly suggested. [2]

Uses of Valdecoxib

Saturday, December 13th, 2008

Since its registration, Bextra was prescribed for pain associated with arthritis, menstrual discomfort, and other ailments.

What is Valdecoxib

Saturday, December 13th, 2008

Valdecoxib is a prescription drug used in the treatment of osteoarthritis, rheumatoid arthritis, and painful menstruation and menstrual symptoms. It is classified as a nonsteroidal anti-inflammatory drug, or NSAID, and should not be taken by anyone allergic to these types of medications.

Valdecoxib was manufactured and marketed under the brand name Bextra by G. D. Searle & Company. It was approved by the United States Food and Drug Administration on November 20, 2001[1], and was available by prescription in tablet form until 2005, when it was removed from the market due to concerns about possible increased risk of heart attack and stroke.

Other effects of Rofecoxib

Saturday, December 13th, 2008

Rofecoxib was shown to improve premenstrual acne vulgaris in a placebo controlled study.[14]

Political impact of Vioxx litigation in America

Saturday, December 13th, 2008

The recall and litigation over rofecoxib has provoked debate over drug safety in the United States. Some argue that the U.S. Food and Drug Administration does not do enough to monitor product safety and that the rofecoxib withdrawal is an argument against tort reform. It has also been argued that litigation is an imperfect means of regulation that would overdeter companies for complying with FDA requirements, and that large awards like that in Ernst would inhibit research and development.

Litigation of Rofecoxib

Saturday, December 13th, 2008

As of March 2006, there had been over 10,000 cases and 190 class actions filed against Merck over adverse cardiovascular events associated with rofecoxib and the adequacy of Merck’s warnings. The first wrongful death trial, Rogers v. Merck, was scheduled in Alabama in the spring of 2005, but was postponed after Merck argued that the plaintiff had falsified evidence of rofecoxib use.[11]

On August 19, 2005, a jury in Texas voted 10-2 to hold Merck liable for the death of Robert Ernst, a 59-year old man who allegedly died of a rofecoxib-induced heart attack. The plaintiffs’ lead attorney was Mark Lanier. Merck argued that the death was due to cardiac arrhythmia, which had not been shown to be associated with rofecoxib use. The jury awarded Carol Ernst, widow of Robert Ernst, $253.4 million in damages. This award will almost certainly be capped at no more than USD$26.1 million because of punitive damages limits under Texas law.[12] As of March 2006, the plaintiff had yet to ask the court to enter a judgment on the verdict; Merck has stated that it will appeal.

On November 3, 2005, Merck won the second case Humeston v. Merck, a personal injury case, in Atlantic City, New Jersey. The plaintiff experienced a mild myocardial infarction and claimed that rofecoxib was responsible, after having taken it for two months. Merck argued that there was no evidence that rofecoxib was the cause of Humeston’s injury and that there is no scientific evidence linking rofecoxib to cardiac events with short durations of use. The jury ruled that Merck had adequately warned doctors and patients of the drug’s risk.[13]

The first federal trial on rofecoxib, Plunkett v. Merck, began on November 29, 2005 in Houston, Texas. The trial ended in a hung jury and a mistrial was declared on December 12, 2005. According to the Wall Street Journal, the jury hung by an eight to one majority, favoring the defense. Upon retrial in February 2006 in New Orleans, Louisiana, where the Vioxx multidistrict litigation (MDL) is based, a jury found Merck not liable, even though the plaintiffs had the NEJM editor testify as to his objections to the VIGOR study.

On January 30, 2006, a New Jersey state court dismissed a case brought by Edgar Lee Boyd, who blamed Vioxx for gastrointestinal bleeding that he experienced after taking the drug. The judge said that Boyd failed to prove the drug caused his stomach pain and internal bleeding.

In January 2006, Garza v. Merck began trial in Rio Grande City, Texas. The plaintiff, a 71-year-old smoker with heart disease, had a fatal heart attack three weeks after finishing a one-week sample of rofecoxib. On April 21, 2006 the jury awarded the plaintiff $7 million compensatory and $25 million punitive. The punitive amount will be reduced to under $1 million.

On April 5, 2006, the jury held Merck liable for the heart attack of 77-year-old John McDarby, and awarded Mr McDarby $4.5 million in compensatory damages based on Merck’s failure to properly warn of Vioxx safety risks. After a hearing on April 11, 2006, the jury also awarded Mr McDarby an additional $9 million in punitive damages. The same jury found Merck not liable for the heart attack of 60-year-old Thomas Cona, a second plaintiff in the trial, but was liable for fraud in the sale of the drug to Cona.

Merck has reserved $970 million to pay for its Vioxx-related legal expenses through 2007, and have set aside $4.85bn for legal claims from US citizens. Patients who claim to have suffered as a result of taking Vioxx in countries outside the US are campaigning for this to be extended.

Withdrawal of Rofecoxib

Saturday, December 13th, 2008

Due to the findings of its own APPROVe study, Merck publicly announced its voluntary withdrawal of the drug from the market worldwide on September 30, 2004 [11].

In addition to its own studies, on September 23, 2004 Merck apparently received information about new research by the FDA that supported previous findings of increased risk of heart attack among rofecoxib users (Grassley, 2004). FDA analysts estimated that Vioxx caused between 88,000 and 139,000 heart attacks, 30 to 40 percent of which were probably fatal, in the five years the drug was on the market.

On November 5 the medical journal The Lancet published a meta-analysis of the available studies on the safety of rofecoxib (Jüni et al., 2004). The authors concluded that, owing to the known cardiovascular risk, rofecoxib should have been withdrawn several years earlier. The Lancet published an editorial which condemned both Merck and the FDA for the continued availability of rofecoxib from 2000 until the recall. Merck responded by issuing a rebuttal of the Jüni et al. meta-analysis that noted that Juni omitted several studies that showed no increased cardiovascular risk. (Merck & Co., 2004).

In 2005, advisory panels in both the U.S. and Canada encouraged the return of rofecoxib to the market, stating that rofecoxib’s benefits outweighed the risks for some patients. The FDA advisory panel voted 17-15 to allow the drug to return to the market despite being found to increase heart risk. The vote in Canada was 12-1, and the Canadian panel noted that the cardiovascular risks from rofecoxib seemed to be no worse than those from ibuprofen[10] — though the panel recommended that further study was needed for all NSAIDs to fully understand their risk profiles. Notwithstanding these recommendations, Merck has not returned rofecoxib to the market.

Merck hired a firm in 2005, Debevoise & Plimpton, to investigate Vioxx study results and communications conducted by Merck.[citation needed] Through the report, it was found that Merck’s senior management acted in good faith, and that the confusion over the clinical safety of Vioxx was due to the sales team’s overzealous behavior. The report that was filed gave a timeline of the events surrounding Vioxx and showed that Merck intended to operate honestly throughout the process. Any mistakes that were made regarding the mishandling of clinical trial results and withholding of information was the result of oversight, not malicious behavior. The Martin Report did conclude that the Merck’s marketing team exaggerated the safety of Vioxx and replaced truthful information with sales tactics.[citation needed] The report was published in February 2006, and Merck was satisfied with the findings of the report and promised to consider the recommendations contained in the Matin Report.

Other NSAIDs of Rofecoxib

Saturday, December 13th, 2008

Since the withdrawal of Vioxx it has come to light that there may be negative cardiovascular effects with not only other COX-2 inhibitiors, but even the majority of other NSAIDs. It is only with the recent development of drugs like Vioxx that drug companies have carried out the kind of well executed trials that could establish such effects and these sort of trials have never been carried out in older “trusted” NSAIDs such as ibuprofen, diclofenac and others. The possible exceptions may be aspirin and naproxen due to their anti-platelet properties.

Other COX 2 inhibitors

Saturday, December 13th, 2008

Any increased risk of renal and arrhythmia pathologies associated with the class of COX-2, inhibitors, e.g. celecoxib (Celebrex), valdecoxib (Bextra), parecoxib (Dynastat), lumiracoxib, and etoricoxib is not evident[8], although smaller studies[9] had demonstrated such effects earlier with the use of celecoxib, valdecoxib and parecoxib.

Nevertheless, it is likely that trials of newer drugs in the category will be extended in order to supply additional evidence of cardiovascular safety. Examples are some more specific COX-2 inhibitors, including etoricoxib (Arcoxia) and lumiracoxib (Prexige), which are currently (circa 2005) undergoing Phase III/IV clinical trials.

Besides, regulatory authorities worldwide now require warnings about cardiovascular risk of COX-2 inhibitors still on the market. For example, in 2005, EU regulators required the following changes to the product information and/or packaging of all COX-2 inhibitors [10]:
Contraindications stating that COX-2 inhibitors must not be used in patients with established ischaemic heart disease and/or cerebrovascular disease (stroke), and also in patients with peripheral arterial disease
Reinforced warnings to healthcare professionals to exercise caution when prescribing COX-2 inhibitors to patients with risk factors for heart disease, such as hypertension, hyperlipidaemia (high cholesterol levels), diabetes and smoking
Given the association between cardiovascular risk and exposure to COX-2 inhibitors, doctors are advised to use the lowest effective dose for the shortest possible duration of treatment

Other studies of Rofecoxib

Saturday, December 13th, 2008

Pre-approval Phase III clinical trials, like the APPROVe study, showed no increased relative risk of adverse cardiovascular events for the first eighteen months of rofecoxib usage (Merck, 2004). Others have pointed out that “study 090,” a pre-approval trial, showed a 3-fold increase in cardiovascular events compared to placebo, a 7-fold increase compared to nabumetone (another [NSAID]), and an 8-fold increase in heart attacks and strokes combined compared to both control groups [8] [9]. Although this was a relatively small study and only the last result was statistically significant, critics have charged that this early finding should have prompted Merck to quickly conduct larger studies of rofecoxib’s cardiovascular safety. Merck notes that it had already begun VIGOR at the time Study 090 was completed. Although VIGOR was primarily designed to demonstrate new uses for rofecoxib, it also collected data on adverse cardiovascular outcomes.

Several very large observational studies have also found elevated risk of heart attack from rofecoxib. For example, a recent retrospective study of 113,000 elderly Canadians suggested a borderline statistically significant increased relative risk of heart attacks of 1.24 from Vioxx usage, with a relative risk of 1.73 for higher-dose Vioxx usage. (Levesque, 2005). Another study, using Kaiser Permanente data, found a 1.47 relative risk for low-dose Vioxx usage and 3.58 for high-dose Vioxx usage compared to current use of celecoxib, though the smaller number was not statistically significant, and relative risk compared to other populations was not statistically significant. (Graham, 2005).

Furthermore, a more recent meta-study of 114 randomized trials with a total of 116,000+ participants, published in JAMA, showed that Vioxx uniquely increased risk of renal (kidney) disease, and heart arrhythmia. COX-2 Inhibitor Drug Review of adverse renal and arrhythmia risk, in JAMA 2006