Safety and pharmacokinetics of sirolimus-eluting stents in the canine cerebral vasculature: 180 day assessment.
OBJECTIVE
We evaluated local and systemic pharmacokinetics and pharmacodynamics of sirolimus-eluting stents (SES) in canine cerebral vessels.


METHODS
SES (1.5 x 8 mm, 79 microg/479 microg sirolimus) and control stents (1.5 x 8 mm stainless steel with or without polymer) were implanted in canine basilar and ventral spinal arteries. Animals were sacrificed for local pharmacokinetic (36 animals at 1, 3, 8, 30, 90, 180 days) and pharmacodynamic (60 animals at 3, 30, 90, 180 days) assessment.


RESULTS
Postrecovery adverse clinical events were not serious, requiring no unscheduled treatment. Histologically, brain and spinal cord sections revealed scattered microinfarcts and minimal gliosis consistent with postprocedure changes in all four stent-treatment groups. All stented vessels at all time points demonstrated good luminal patency with low injury and inflammation scores and no thrombosis of either stented or branch arteries. Endothelialization was complete in all stent groups by 30 days. Intimal smooth muscle cell scores were reduced in both SES groups at 30, 90, and 180 days. Systemic sirolimus levels peaked between 1 and 7 hours postimplant (maximum concentration, 1.2 +/- 1.47, 79 microg; 4.5 +/- 1.23 ng/ml, 479 microg), then declined rapidly to 1 ng/ml or less by 96 hours. Peak local tissue sirolimus levels were 41.5 ng/mg (79 microg) and 65 ng/mg (479 microg).


CONCLUSIONS
SES in canine cerebral vessels were associated with good luminal patency to 180 days, with complete endothelialization and no evidence of acute thrombosis. This model has shown that SES deployed within the brain do not cause neurotoxicity during a 180-day time course, even when exaggerated doses are used. The findings support the contention that SES are safe to use and maintain patency in cerebral vessels.
Levy
Elad I
EI
Department of Neurosurgery, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York 14209, USA.
Hanel
Ricardo A
RA
Tio
Fermin O
FO
Garlick
David S
DS
Bailey
Lynn
L
Cunningham
Mark R
MR
Williard
Clark
C
Sherman
Darren
D
Dooley
John F
JF
Kopia
Gregory A
GA
D000818:Animals; D002536:Cerebral Arteries / Q000473:pathology / Q000503:physiopathology; D002544:Cerebral Infarction / Q000209:etiology / Q000473:pathology; D004285:Dogs; D016503:Drug Delivery Systems; D004730:Endothelium, Vascular / Q000254:growth & development; D005260:Female; D005911:Gliosis / Q000209:etiology / Q000473:pathology; D007238:Infarction / Q000209:etiology / Q000473:pathology; D008297:Male; D020123:Sirolimus / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000627:therapeutic use; D013116:Spinal Cord / Q000098:blood supply; D015607:Stents / Q000009:adverse effects; D013997:Time Factors; D014654:Vascular Patency
D020123:Sirolimus