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Hypertension Drug May Help Sickle Cell Patients

Posted on: Wednesday, 31 May 2006, 12:00 CDT

By Roger Schlueter, Belleville News-Democrat, Ill.

May 23--ST. LOUIS -- Sickle cell disease by itself is bad enough with its periodic episodes of body-wracking pain. But add the common complication of high blood pressure in the lungs, and you're talking about a potential death sentence.

St. Louis University researchers are seeking volunteers to test the first treatment that may alleviate both sickle cell and the pulmonary hypertension at the same time.

Pulmonary arterial hypertension, which is high blood pressure in the arteries that feed the lungs, affects 30 percent of patients who have sickle cell disease. More than 50,000 patients in the United States have both conditions. The drug being tested already has been approved to treat the hypertension alone.

"Pulmonary hypertension is one of the main causes of death in patients who have sickle cell disease," said Dr. Wilman Ortega, an assistant professor of pulmonary, critical care and sleep medicine and chief investigator for the new study. "If left untreated, a lot of patients with both conditions die within two and a half years."

St. Louis University is one of 24 centers around the world -- and the only one in Missouri -- that will study the safety and effectiveness of the drug in lowering the blood pressure and reducing the number of sickle cell crises. The school is looking to recruit 10 volunteers to test the drug.

Between 1 percent and 2 percent of those of African parentage have sickle cell disease, so named for the red blood cells that warp into a sickle shape when depleted of oxygen. This odd shape makes it difficult for the cells to flow through blood vessels as easily as healthy oval-shaped blood cells.

"A sickle cell crisis can be triggered by infection and dehydration," said Ortega, who noted that the disease also can affect those of Mediterranean, Caribbean, Arabian, East Indian and South and Central American descent.

"(Crises) occur when patients experience extreme pain in their legs, back, hips and chest because red blood cells become rigid and block blood vessels. We treat the symptoms with pain medications, antibiotics if there's an infection, possible blood transfusions and fluids. However, there is no specific treatment for sickle cell disease itself, and more research is really needed in this area."

Adding to the problem, the blood vessels of patients who have pulmonary hypertension become thick and narrow, reducing blood flow and raising pressure in the lungs. This forces the heart to work harder to pump enough blood through the lungs, where it picks up oxygen. Eventually, the heart gives out.

Worse, patients who have sickle cell disease may not realize they have pulmonary hypertension until they have later-stage symptoms such as fatigue, dizziness and shortness of breath. That's why Ortega urges all sickle cell patients to be periodically screened for pulmonary hypertension.

"If they have sickle cell disease, they could easily have pulmonary hypertension," Ortega said. "They need to go to their physician and make their doctors aware they should get an echocardiogram, which screens for pulmonary hypertension."

Those with hypertension should consider entering the new study. Those eligible should be over 18 and have both shortness of breath and sickle cell disease. All applicants will be given an echocardiogram, a right heart catheterization and a lung function test to determine the severity of their disease. They also will be asked to walk for six minutes to see if they experience breathlessness.

Of those who qualify for the clinical trial, half will receive an oral medication that blocks a hormone called endothelin, which constricts vessels and raises pulmonary artery pressure. The other half will receive a placebo.

Those in the study will take the drug twice a day, and their blood will be monitored every two weeks. If patients taking the active medication are tolerating it well, they will switch to a higher dosage after four weeks. After 16 weeks, all patients will have the option of receiving the drug, probably for a year.

Doctors will study whether the medication is safe and effective in treating hypertension -- and whether there is a decrease in the number of hospitalizations due to a sickle cell crisis, Ortega said.

Contact reporter Roger Schlueter at 239-2465 or rschlueter@bnd.com

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Copyright (c) 2006, Belleville News-Democrat, Ill.

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Source: Belleville News-Democrat (Belleville, Ill.)

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