New research from a Case Western Reserve University School of Medicine professor shows that medications that have raised safety concerns over heart attack and stroke risks might not have gotten approval from the Food and Drug Administration (FDA) if the cardiovascular effects of fluid retention had been better understood. Robert P. Blankfield, clinical professor of family medicine and a member of the Department of Family Medicine at University Hospitals Case Medical Center, said fluid retention may explain the increased risk of heart attacks and strokes of medications such as Vioxx, Bextra and Avandia.
His research, published in Clinical Hemorheology and Microcirculation (IOS Press, ISSN 1386-0291), calculates the effects of fluid retention upon the velocity of blood flow and the turbulence of flowing blood. These calculations demonstrate that fluid retention increases the risk of heart attacks and strokes. Since numerous medications cause fluid retention, the paper’s findings have implications to ensure drugs on the market are safe. The pain medications Vioxx and Bextra and the anti-diabetic medication Avandia cause fluid retention. Vioxx and Bextra, known as cyclo-oxygenase-2 (COX-2) inhibitors, were withdrawn from the market because of safety concerns over heart attacks and strokes, and Avandia has been suspected in some reports of increasing the risk of heart attacks.
Blankfield used several basic cardiovascular and hydraulic equations to demonstrate that fluid retention is detrimental for the cardiovascular system.
Fluid retention increases the likelihood that blood will flow in a turbulent manner. Turbulent blood flow accelerates atherosclerosis (hardening of the arteries), thereby increasing the risk of heart attacks and strokes. Many medications cause fluid retention, which raises blood pressure in some, but not all, individuals. Physicians worry about fluid retention if it does raise blood pressure, but are unconcerned when blood pressure is unaffected.
“This paper demonstrates that fluid retention is unhealthy because it increases the likelihood that blood will flow in a turbulent manner regardless of whether or not blood pressure is raised. Therefore, drugs that cause the body to retain fluid are dangerous for the cardiovascular system,” Blankfield said.
“If the FDA had been aware of the increased cardiovascular risk that arises from drugs that cause fluid retention, Vioxx, Bextra and Avandia might never have been approved. These findings might spur the FDA to alter some of its current policies,” he continued. “The calculations in this paper might also help pharmaceutical manufacturers screen drugs for their cardiovascular risk at an early stage in the drug development process.” For more information, click here.
Posted by: Emily Mayock, March 9, 2011 09:12 AM | News Topics: Research
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