You're a wonderful neighbor Don. I hope they called you first! The drug is tPA (tissue plasminogen activator) and must be administered directly to the clot (via angiography) within 3 hours of an ischemic event (won't help in a hemorrhagic stroke) . Catching it early avoids infarction down stream of the clot. One of the biggest causes of strokes is high blood pressure. Also, if someone is having a stroke they may appear to suddenly be confused, as happened to Senator Tim Johnson during an interview in 2006. Most have likely heard this before, but, if you suspect someone is having a stroke ask them to speak, smile, or raise their arms. If they have trouble with any of them get them to a stroke center ASAP!