SAN ANTONIO, Texas, Mar 05, 2001 (United Press International via COMTEX) -- Small amounts of a modified clot-busting drug approved for use in heart attacks appears, in preliminary studies, to benefit people with blood clots in the brain, said doctors reporting Monday on the first test of the drug on stroke patients.

The drug, reteplase, was used on nine patients, reported Dr. John Barr, and did not appear to result in bleeding complications -- a problem faced by patients receiving a similar drug, tissue plasminogen activator (t-PA). Barr is director of interventional neuroradiology at Baptist Memorial Hospital, Memphis, Tenn.

"Even though this is preliminary data in a handful of patients, a number of my colleagues nationwide have also been using reteplase for stroke and getting equally encouraging results," Barr said. He reported his findings at the annual scientific meeting of the Society of Cardiovascular and Interventional Radiology in San Antonio

"We use 100th to 1000th of the dose of reteplase in treating people with stroke," said Dr. Buddy Connors, director of interventional neuroradiology at Inova Fairfax Hospital, Falls Church, Va. He said that reteplase is delivered directly to the clot blocking brain arteries through catheter-based technology. Connors is not connected to the first study

Barr said one patient who was treated with reteplase had a severe stroke, and suffered a small bleeding episode when the catheter used to deliver the drug apparently perforated the artery wall. Despite that bleeding, seen in imaging studies, the patient completely recovered. He said he did not believe that bleeding was drug related. Another patient also experienced bleeding during the treatment, Barr said, but that did not cause any new symptoms or problems.

Overall, Barr said, among the 7 patients who had severe strokes and survived them, six showed significant improvement, with their stroke score dropping from 19 -- a marker of a devastating injury -- to 4.9. A score of 0 represents complete recovery. One patient died from complications of the stroke, not from excessive bleeding, Barr reported.

Connors said that, as with t-PA, time is critical for using the clot-busting drugs in the brain. He said patients have to be treated within about three to five hours after symptoms of stroke appear.

"But reteplase circulates longer in the system giving it more of a chance to shrink the clots," he said. Reteplase is essentially t-PA, also known as alteplase, cut in half, said Barr.

Alteplase is metabolized in the liver, requiring large doses of the drug for clot-dissolving effects, Connors said. That increases the risk of bleeding in the brain which can exacerbate the stroke, he said. About 5 to 6 percent of stroke patients receiving alteplase suffer from these devastating bleeds.

Connors said that in the interventional procedure, a catheter is introduced into the blood vessel system through an incision in the groin. The catheter is guided by x-rays to the site of the blood clot in the brain and then tiny amounts of the clotbuster is infused into the area of the blockage. While the dose of drug required to treat heart attacks through an intravenous infusion can cost about $2,000 per treatment, Connors said that doctors use about $2 worth of the drug in treating the blockages in the brain.

Barr said the use of the catheter-based system is more time-consuming than giving the drug intravenously. The procedure takes between one to 2.5 hours, depending on the location of the clot. However, the interventional procedure allows doctors to physically remove some clots that appear too solid to be dissolved.

Barr showed one patient in which such a clot was physically removed using catheter-based equipment and techniques. He said the clot was unlikely to have been dissolved by any available drug treatment.

By ED SUSMAN, UPI Science News

Copyright 2001 by United Press International.

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