"This is really common with a lot of drugs, that there's a ceiling on the effective dose But unfortunately, there's usually not a ceiling on the side effects."
Griffin and her colleagues, who include Wayne A. Ray, Ph.D., professor of Preventive Medicine, and C. Michael Stein, M.D., professor of Medicine, have been sounding the alarm about high-dose Vioxx use since 2002.
In a study of TennCare participants published in the journal Lancet that year, the researchers reported patients on high doses of Vioxx had nearly twice the rate of serious heart problems, including heart attacks and heart-related deaths, compared to patients not on the drug.
Other groups have reported similar findings among high-dose Vioxx users: an increased risk of heart attack and congestive heart failure, a rise in blood pressure and a greater incidence of edema, or swelling, in the arms and legs, which can put extra strain on the heart. Griffin said that high doses of Vioxx might be particularly hard on the kidney, resulting in fluid retention, edema and a rise in blood pressure.
Some doctors won't prescribe Vioxx for patients at risk for developing high blood pressure, because the drug could make that condition more difficult to control, Griffin said. However, many other doctors apparently underestimate the drug's ability to cause edema, hypertension and heart failure, she added.
Of the TennCare patients in the Vanderbilt study who were receiving over 25 milligrams of Vioxx a day, 15 percent had been treated for congestive heart failure during the previous 12 months, and 22 percent had been treated for other forms of heart disease, the researchers reported.