Abstract | INTRODUCTION: Published evidence suggests that phosphoinositide 3 kinase-β (PI3K-β) plays an important role in platelet aggregation and shear activation. TGX-221 is a selective PI3K-β inhibitor with a good separation of anti-thrombotic efficacy and bleeding (therapeutic index) in rats. Our goal was to further evaluate potential of a PI3K-β inhibitor as an anti-thrombotic agent by determining the therapeutic index in another species and efficacy model. Reported effects of TGX-221 in rats were also confirmed. MATERIALS AND METHODS:
TGX-221 (0.3 + 0.3, 1 + 1, 3 + 3 mg/kg + mg/kg/hr, i.v.) or vehicle was given to mice starting 15 min prior to FeCl(3) arterial thrombosis (AT), tail or kidney bleeding time (BT) procedures. RESULTS: Integrated blood flow over 30 min (%baseline mean ± SEM) improved (p < 0.05) with TGX-221 doses 1 + 1 (49 ± 13.9%) and 3+3 (88 ± 10.6%) versus 0.3 + 0.3 (10 ± 0.8%) and vehicle (10 ± 0.6%). Vascular patency (non-occluded/total arteries) improved (p < 0.01) with TGX-221 doses of 3 + 3 (7/8), but not 0.3 + 0.3 (0/8) or 1 + 1 (4/8) versus vehicle (0/8). Tail BT (sec) increased (p < 0.05) with TGX-221 doses of 3 + 3 (median 1560) and 1 + 1 (1305) versus vehicle (225). Mean renal BT (sec) increased (p < 0.05) in all TGX-221 groups (3 + 3: 510 + 26; 1 + 1: 478 + 41; 0.3 + 0.3: 246 + 37) versus vehicle (123 + 9). For comparison, a reference agent, aspirin (30 mpk, i.p.) increased tail BT 1.9X and renal BT 2.6X. CONCLUSIONS: The novel finding of a clear impact on hemostasis by TGX-221 was demonstrated by increased bleeding in two models in mice at anti-thrombotic doses. The results suggest a narrower therapeutic index for this PI3K-β inhibitor than previously recognized, at least for this species.
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Authors | J Eileen Bird, Patricia L Smith, Jeffrey S Bostwick, Petia Shipkova, William A Schumacher |
Journal | Thrombosis research
(Thromb Res)
Vol. 127
Issue 6
Pg. 560-4
(Jun 2011)
ISSN: 1879-2472 [Electronic] United States |
PMID | 21396684
(Publication Type: Journal Article)
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Copyright | Copyright © 2011 Elsevier Ltd. All rights reserved. |
Chemical References |
- Fibrinolytic Agents
- Morpholines
- Phosphoinositide-3 Kinase Inhibitors
- Pyrimidinones
- TGX 221
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Topics |
- Animals
- Bleeding Time
- Blood Platelets
(drug effects)
- Carotid Artery Thrombosis
(blood, drug therapy, enzymology)
- Disease Models, Animal
- Fibrinolytic Agents
(blood, pharmacology, toxicity)
- Hemorrhage
(chemically induced)
- Humans
- Kidney
(blood supply)
- Male
- Mice
- Mice, Inbred C57BL
- Morpholines
(blood, pharmacology, toxicity)
- Phosphatidylinositol 3-Kinases
(blood)
- Phosphoinositide-3 Kinase Inhibitors
- Pyrimidinones
(blood, pharmacology, toxicity)
- Rats
- Rats, Sprague-Dawley
- Tail
(blood supply)
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