The absence of urokinase from the thrombolytic market spawned a search for alternative lytic agents. After a rocky start that included bleeding complications, research focused on combination therapies.
The RELAX trial found that the addition of abciximab, a platelet inhibitor, to reteplase(r-PA), a catheter-directed fibrinolytic, decreased the rate of distal embolic events in patients with acute peripheral arterial occlusive disease. The decrease was statistically significant, Dr. James I. Swischuk said on Tuesday at the 11th annual Advanced Interventional Management Symposium in New York City.
Only 5% of patients receiving the combination of r-PA and abciximab had distal embolization requiring intervention, compared with 31% of those receiving r-PA alone.
The 74 patients in the multicenter, dose-escalating, phase II trial received intra-arterial r-PA at 0.1, 0.2, 0.5, or 1 unit per hour. Thirty-eight patients also received intravenous abciximab for the duration of r-PA infusion. Infusion continued until patency was restored, ischemia worsened, serious hemorrhage occurred, or the protocol was completed.
The researchers found that patients who received combination therapy had slightly shorter infusions and slightly higher patency rates, although these were not statistically significant.
Major bleeding occurred in 15% of the monotherapy group versus 20% of the combination group. None of the patients had intracranial hemorrhagic events. The researchers concluded that there was no relationship between thrombolytic dose and bleeding.
?A trend of decreased thrombolytic efficacy at 0.1 unit per hour of reteplase suggests that reteplase at 0.2 unit per hour or higher with or without abciximab provides the best balance of efficacy and safety for acute occlusions,? said Swischuk, a clinical associate professor of radiology at the University of Illinois College of Medicine.
Larger studies need to be conducted to confirm these results, Swischuk said.
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