title: In vitro effect of pimobendan on platelet aggregation in dogs.
abstract: OBJECTIVE
  To determine whether pimobendan has in vitro antithrombotic properties through inhibition of platelets in canine blood samples.
  
  
  METHODS
  10 healthy adult dogs.
  
  
  METHODS
  Blood samples were collected from each dog into tubes containing hirudin or sodium citrate. Pimobendan was added to blood samples (final concentration, 0.0, 0.01, 0.1, 1.0, or 10.0μM) containing hirudin prior to undergoing collagen- and ADP-induced whole blood impedance aggregometry. Plasma thromboxane concentrations were measured after platelet aggregation. Pimobendan was also added to blood samples (0.0, 0.01, or 10.0μM) containing sodium citrate prior to thromboelastographic evaluation.
  
  
  RESULTS
  Compared with findings for 0.0μM pimobendan, composite platelet aggregation (area under the curve [AUC]) and maximal platelet aggregation (aggregation units [AUs]) at 10.0μM pimobendan were significantly decreased for collagen-induced aggregation (AUC, 349.7 ± 58.4 vs 285.1 ± 72.2; maximal platelet aggregation, 196.2 ± 25.8 AUs vs 161.5 ± 38.0 AUs), and the AUC and velocity of aggregation at 10.0μM pimobendan were significantly decreased for ADP-induced aggregation (AUC, 268.5 ± 35.1 vs 213.4 ± 77.2; velocity of aggregation, 15.7 ± 2.9 AUs/min vs 11.8 ± 3.5 AUs/min). Pimobendan had no significant effect on plasma thromboxane concentration or thromboelastographic variables, regardless of concentration.
  
  
  CONCLUSIONS
  In vitro, pimobendan had an antiplatelet effect in canine blood samples at a concentration 1,000-fold higher than that clinically achievable. These antiplatelet properties do not appear to contribute to the positive clinical profile of the drug in dogs. Pimobendan administration would not appear to confer a risk for bleeding and does not have to be avoided in dogs with thrombocytopenia or those concurrently receiving antiplatelet drugs.
authors: Department of Veterinary Clinical Sciences and the Veterinary Teaching Hospital, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA.
authors: Eryn A
authors: EA
authors: Shipley
authors: Daniel F
authors: DF
authors: Hogan
authors: Nonya N
authors: NN
authors: Fiakpui
authors: Aliya N
authors: AN
authors: Magee
authors: Henry W
authors: HW
authors: Green
authors: Kimberly A
authors: KA
authors: Sederquist
mesh_terms: D000818:Animals; D019540:Area Under Curve; D002316:Cardiotonic Agents / Q000494:pharmacology*; D004285:Dogs / Q000097:blood*; D005260:Female; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*; D011724:Pyridazines / Q000494:pharmacology*; D013931:Thromboxanes / Q000097:blood
chemical_list: D002316:Cardiotonic Agents; D011724:Pyridazines; D013931:Thromboxanes; C041648:pimobendan