Thrombolytics & t-PA

H2H Summer 2012 Stroke Brain

In the case of ischemic stroke, a thrombolytic drug is administered intravenously to help dissolve blood clots in arteries and reestablish blood flow to the brain. A stroke is a dynamic process that typically kills 2 million nerve cells per minute over approximately eight hours. When the thrombolytic drug is administered, it can interrupt the stroke and prevent loss of more nerve cells.

The 1st Engineered Thrombolytic for Stroke Treatment

Our bodies produce tissue plasminogen activator (tPA), an enzyme that changes the plasminogen in our bodies into another enzyme, which dissolves blood clots. The first engineered thrombolytic for stroke treatment was approved by the Food & Drug Administration in 1996. That thrombolytic is a man-made enzyme called tissue plasminogen activator (tPA) — an enzyme that changes or activates plasminogen in the human body into another enzyme that can dissolve a blood clot.

TPA has been genetically engineered so that it can also be administered intravenously to dissolve the very serious clots associated with stroke. It is available in most hospital emergency departments throughout the United States and is approved for qualifying patients who arrive at the hospital within three hours of symptom onset.

Administering tPA at Onset of Symptoms

This three-hour window was set because initial tPA trials revealed that the drug is most effective when administered within three hours of the onset of symptoms. In terms of stroke outcomes at three months, the administration of the thrombolytic drug at one hour after stroke symptom onset is 3.5 times more effective than administration at three hours after symptom onset. Earlier administration is better.  The primary goal remains to be prompt administration of IV tPA to appropriate patients as soon as possible after the onset of symptoms.

An international study provided evidence that the use of tPA can be safe and effective up to 4.5 hours after the onset of symptoms - another advancement in stroke treatment.