For those of you who have been following the St. Joseph Medical Center stent fiasco, a story in the Los Angeles Times regarding the anti-clotting drug Plavix brings home a new concern for the patients who received this drug as part of the post-procedure therapy. Plavix is used “to prevent clotting of blood in patients who have stents or other prostheses or conditions that predispose them to clotting, and thus strokes and heart attacks.”
The Food and Drug Administration said Friday that it will require a new black-box warning on the label of the popular anti-clotting drug Plavix to indicate that some patients do not metabolize the drug properly and may receive little benefit from it. The warning indicates that the drug is dangerous only in the sense that it doesn’t work in those patients and thus may leave them unprotected against heart attacks and strokes.
“The new warning appears on the label of the drug in a black box — hence the name — which is considered the most severe form of warning.” A black box warning is the strongest warning required by the FDA. The intent of requiring such a warning is to alert physicians and help them treat their patients correctly. “The FDA says between 2% and 14% of Plavix users don’t respond well to the drug and might benefit from alternative treatment.”
According to the FDA press release:
Plavix reduces the risk of heart attack, unstable angina, stroke, and cardiovascular death in patients with cardiovascular disease by making platelets less likely to form blood clots. Plavix does not have its anti-platelet effects until it is metabolized into its active form by the liver enzyme, CYP2C19.
People who have reduced functioning of their CYP2C19 liver enzyme cannot effectively convert Plavix to its active form. As a result, Plavix may be less effective in altering platelet activity in those people. These “poor metabolizers” may not receive the full benefit of Plavix treatment and may remain at risk for heart attack, stroke, and cardiovascular death.
A Wall Street Journal Blog suggests that this situation may actually make the physicians’ job more difficult.
Genetic testing could identify the poor responders. But most doctors aren’t well equipped to do genetic testing. They don’t have quick access to the tests. Even if they did, they might not have time in the cases of many patients to wait for results to come back.
Only one genetic test has been approved by the FDA, Roche’s AmpliChip, “to look for the variation, but not specifically for determining treatment with Plavix. Many laboratories offer other tests, whose quality the FDA says doctors will have to assess before using. Doctors should make sure the tests are at least 98% accurate, FDA officials told reporters.”
According to Christopher Cannon, a Harvard Medical School associate professor and editor-in-chief of Cardiosource, associations involved with the cardiac-related specialties and sub-specialties “will need to develop protocols for testing and treatment. The alternatives include increasing the dose of Plavix or switching to bloodthinner Prasugrel from Lilly and Daiichi Sankyo, but Cannon says neither has been tested for that purpose.”
“Thus a real conundrum” for patients and their physicians, Cannon said. “I expect mass confusion in response to this FDA warning,” he added.
As we reported in “Eye Opener” on March 13, 2010, St. Joseph Medical Center this past week added another 169 patients to the list of those notified by letter that they had received unnecessary, expensive and potentially dangerous stent procedures. This brought the number notified to a whopping 538 patients – at least to date.
One has to wonder in all of this, was there a single moment of thought given to the potential risks to the patients at St. Joseph Medical Center when these unnecessary stents were put in hundreds of patients? Maybe those involved in this tragic story of despicable care were not fully versed in the genetic complication of Plavix (or maybe they were); however, they were most assuredly aware that they were exposing these unwitting patients to a risk of hemorrhage, not to mention the risks associated with having a foreign body unnecessarily placed in their coronary vessels.