Blood Pressure Drug Needs New Cautions, Expert Panel Says
FDA Attention Prompted by Citizen Petition Against CarduraMay 24, 2001 | WebMD The FDA needs to communicate to doctors that there may be safety questions with the popular Pfizer blood pressure drug Cardura, according to recommendations Thursday from an expert committee to the agency.
But the panel wasn't sure yet how updated labels for the drug should advise doctors. Jeffrey Borer, MD, the panel's acting chair, tells WebMD, 'Something to doctors is warranted, but not at this particular second, because we don't know what to tell them.'
The panel, the FDA's Cardiovascular and Renal Drugs Advisory Committee, voted against recommending that any cautionary message should go to patients. It also voted overwhelmingly against relegating the drug as a 'second-line' therapy against high blood pressure.
The committee's votes were prompted by a 'citizen petition' from several former Cardura users to get the FDA to impose tighter controls on the blood pressure drug, known generically as doxazosin mesylate and part of a class of drugs known as alpha blockers.
The drug, the petition claimed, is dangerously linked to higher rates of congestive heart failure and stroke.
In March 2000, the NIH announced the suspension of a large-scale study of Cardura that it was funding with Pfizer. The study had found that patients were twice as likely to be hospitalized for congestive heart failure than if they were on an older -- and less expensive -- diuretic known as chlorthalidone. And compared with patients taking the diuretic, Cardura patients in the study were also more likely to suffer a stroke, which was part of an unprecedented long-term comparison of blood pressure drugs.
According to the petition, "An enhanced risk of heart failure due to the misinformed use of Cardura as a 'first-line' treatment is not tolerable where there are cheaper, more effective treatments or combinations of drugs that may be used and the adverse consequences are potentially critical."
But Pfizer officials on Thursday maintained that the drug is safe, noting that dozens of comparative studies of the drug have shown no link to congestive heart failure, stroke, or other heart conditions. It said that no FDA action was necessary.
The company noted that the study in question involved older patients who were already at a high risk of heart disease. And it said that the higher rate of heart disease with Cardura patients didn't indicate that Cardura caused heart failure, but simply that the diuretic had a beneficial effect on cardiac events.
The advisory panel agreed on that point Thursday, voting unanimously against saying that Cardura caused heart failure and other adverse outcomes.
Other parts of the NIH blood pressure drug trial are still under way, but the FDA doesn't have access to data that the expert panel said was crucial in trying to craft any cautions on the drug. The trial isn't scheduled to conclude until next March.
As a result, the panel struggled to find a way to deal with the concerns over the drug's safety. Panel guest Marvin Konstam, MD, said, "There is something going on here. ... The results of the trial ought to be communicated." And panel member Thomas Graboys, MD, said he was troubled by the study's findings. "I won't prescribe the drug and I would pull my patients off the drug."
But panel member Steven Nissen, MD, questioned how the FDA could issue any warnings on the drug when it didn't have information on the average doses of Cardura that were used in the trial. "There's too much that we don't know here," he said. "We're off base to try to make a regulatory decision."
The FDA usually follows its advisory committees' lead but is not bound by their votes.
The petition called for prominent warning labels on the drug and would require that Pfizer notify all Cardura patients of the trial results, and it would also force the FDA to inform the public of the trial's results.
"They were asking a lot," Borer tells WebMD.
The petition claimed that Pfizer has refused to publicize the drug's dangers in order to protect its profits.
After the NIH trial was suspended, the petition alleges, the company acted to maintain high sales of the drug by making the continued claim to doctors that the drug was safe and effective as a primary therapy against high blood pressure.
The consumer advocacy group Public Citizen said that the FDA needed to take regulatory steps to "maximize the odds that few if any newly diagnosed hypertensive patients are started on alpha blockers such as Cardura, and that most, if not all hypertensive patients now using such drugs are switched to other agents."
In March 2000, the American College of Cardiology issued an advisory that doctors should "carefully reassess" their use of Cardura.
But the citizen petition claimed that relatively few doctors appeared to be aware of the NIH trial's findings, and were likely continuing to prescribe Cardura when it might be dangerous.