Extension of the therapeutic window for recombinant tissue plasminogen activator with argatroban in a rat model of embolic stroke.
OBJECTIVE
Argatroban, a specific thrombin inhibitor, has been shown to reduce ischemic lesion size after focal cerebral ischemia in rats. In addition, recombinant tissue plasminogen activator (rtPA) has been shown to reduce ischemic lesion size in both rats and humans if given within 3 hours of symptom onset. We tested the hypothesis that the administration of argatroban with rtPA could extend the treatment window of stroke to 4 hours without increasing gross cerebral hemorrhage rates or reducing efficacy.


METHODS
Male Wistar rats were subjected to middle cerebral artery (MCA) occlusion by a single fibrin-rich clot. After embolization, rats were administered argatroban at the following dose levels: 2.08, 6.25, and 18.75 microgram . kg(-1). min(-1). In a second experiment, rats received argatroban (6.25 microgram . kg(-1). min(-1)) or argatroban in combination with rtPA 4 hours after MCA occlusion. Tissue sections were then analyzed for lesion volume, gross hemorrhage and fibrin deposition.


RESULTS
The 6.25 microgram. kg(-1). min(-1) dose demonstrated a significant reduction (P<0.05) in lesion volume after 48 hours (27.2+/-6.3%) compared with controls (35.3+/-3.7%). A significant reduction (P<0.05) in lesion volume was observed in the argatroban-plus-rtPA group (17.1+/-10.4%) compared with controls (35.3+/-3.7%). No increase in hemorrhagic transformation was observed. Fibrin deposition in the ipsilateral cortical microvasculature was significantly decreased in the 4-hour combination argatroban-plus-rtPA group compared with the controls (P<0.05).


CONCLUSIONS
This study demonstrates that the combination of argatroban and rtPA extends the window of opportunity for treatment of stroke to 4 hours without increasing hemorrhagic transformation.
Morris
D C
DC
Department of Emergency Medicine, Henry Ford Health Sciences Center, Detroit, Michigan, USA.
Zhang
L
L
Zhang
Z G
ZG
Lu
M
M
Berens
K L
KL
Brown
P M
PM
Chopp
M
M
D000818:Animals; D000991:Antithrombins / Q000627:therapeutic use*; D001120:Arginine / Q000031:analogs & derivatives; D002545:Brain Ischemia / Q000188:drug therapy / Q000473:pathology; D002543:Cerebral Hemorrhage / Q000453:epidemiology; D004305:Dose-Response Relationship, Drug; D005337:Fibrin / Q000032:analysis; D015994:Incidence; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy* / Q000473:pathology; D020766:Intracranial Embolism / Q000188:drug therapy / Q000473:pathology; D008297:Male; D010875:Pipecolic Acids / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000627:therapeutic use; D020521:Stroke / Q000188:drug therapy*; D013449:Sulfonamides; D013997:Time Factors; D010959:Tissue Plasminogen Activator / Q000235:genetics / Q000627:therapeutic use*
D000991:Antithrombins; D010875:Pipecolic Acids; D011994:Recombinant Proteins; D013449:Sulfonamides; D005337:Fibrin; D001120:Arginine; D010959:Tissue Plasminogen Activator; C031942:argatroban