title: Effects of different thrombolytic treatment regimen with abciximab and tirofiban on platelet aggregation and platelet-leukocyte interactions: a subgroup analysis from the GUSTO V and FASTER trials.
abstract: BACKGROUND
  Due to considerably high rates of reocclusion under standard thrombolytic therapy GP IIb/IIIa inhibitors have been combined with thrombolytics to improve therapeutic outcomes. Potential reasons for arterial reocclusion may be increased platelet activation, interaction of platelets with other cell types such as leukocytes and inadequate drug dosing due to lack of ideal platelet monitoring. We compared combination therapy regimens consisting of GP IIb/IIIa inhibitors and thrombolytics with respect to platelet inhibition and platelet-leukocyte interactions.
  
  
  RESULTS
  From the GUSTO V trial (standard rPA vs. reduced dose rPA and abciximab) and the FASTER trial (standard TNK-tPA vs. reduced dose TNK-tPA and tirofiban) 15 patients were monitored by platelet aggregometry, rapid platelet function assay (RPFA) and flow cytometry (FC). rPA alone (n = 5) caused initial increases in platelet aggregation. However, platelet aggregation was significantly (p < 0.05) and sufficiently (>80%) inhibited by abciximab/rPA (n = 5) and tirofiban/TNK-tPA (n = 5). The platelet inhibitory effect of tirofiban/TNK-tPA was more pronounced compared to abciximab/rPA with a significant difference after 2 h (p < 0.05). Tirofiban/TNK-tPA and abciximab/rPA caused decreases in platelet-leukocyte aggregates as well as in binding of specific antibodies to the platelet vitronectin receptor and P-selectin (p < 0.05, respect.). No differences among the treatment groups were seen with respect to antibody binding to MAC-1 and CD154/CD40 ligand.
  
  
  CONCLUSIONS
  Taken together, GP IIb/IIIa inhibitors overcome the platelet activating effect of thrombolytics resulting in sufficient platelet inhibition. RPFA is a suitable monitoring tool to accurately assess platelet inhibition. Within the given combination treatment regimen tirofiban appears to be more effective compared to abciximab and to exert effects beyond the inhibition of GP IIb/IIIa.
authors.affiliation: Department of Cardiology, University of Heidelberg, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Bertram
authors.forename: Martin
authors.initials: M
authors.lastname: Moser
authors.forename: Karlheinz
authors.initials: K
authors.lastname: Peter
authors.forename: Helmut F
authors.initials: HF
authors.lastname: Kuecherer
authors.forename: Raffi
authors.initials: R
authors.lastname: Bekeredjian
authors.forename: Andreas
authors.initials: A
authors.lastname: Straub
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Nordt
authors.forename: Christoph
authors.initials: C
authors.lastname: Bode
authors.forename: Johannes
authors.initials: J
authors.lastname: Ruef
mesh_terms: D000077284:Abciximab; D000704:Analysis of Variance; D000911:Antibodies, Monoclonal / Q000494:pharmacology* / Q000627:therapeutic use; D002986:Clinical Trials as Topic / Q000379:methods; D004359:Drug Therapy, Combination; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000494:pharmacology* / Q000627:therapeutic use; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects* / Q000502:physiology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors / Q000378:metabolism; D015912:Thrombolytic Therapy / Q000379:methods; D000077466:Tirofiban; D014443:Tyrosine / Q000031:analogs & derivatives / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000911:Antibodies, Monoclonal; D007140:Immunoglobulin Fab Fragments; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D014443:Tyrosine; D000077466:Tirofiban; D000077284:Abciximab