Journal of thrombosis and thrombolysis
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J. Thromb. Thrombolysis · Apr 2001
ReviewPlatelet aggregation inhibition with glycoprotein IIb--IIIa inhibitors.
Inhibitors of the platelet receptor glycoprotein (GP) IIb--IIIa are a novel and potent class of antithrombotic drugs for the management of patients with non-ST-segment elevation acute coronary syndromes (ACS) and those undergoing percutaneous coronary intervention (PCI). Pharmacodynamic studies with three currently approved agents in this class (abciximab [ReoPro, Centocor, Inc., Malvern, Pennsylvania, and Eli Lilly & Company, Indianapolis, Indiana]; eptifibatide [INTEGRILIN, COR Therapeutics, Inc., South San Francisco, California, and Key Pharmaceuticals, Inc., Kenilworth, New Jersey]; and tirofiban HCI [Aggrastat, Merck & Co., Inc., Whitehouse Station, New Jersey]) all sought to identify dosing regimens that would establish and maintain >80 % inhibition of ex vivo platelet aggregation throughout the duration of intravenous infusion. Direct comparison of these prior studies is difficult, however, because the assays used different anticoagulants (sodium citrate [abciximab, tirofiban HCI] or D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone [PPACK] [eptifibatide]) and different concentrations of the platelet agonist adenosine diphosphate (ADP) (5 micromol [tirofiban HCI] or 20 micromol [abciximab, eptifibatide]). ⋯ Of the three currently approved GP IIb--IIIa inhibitors, eptifibatide is the only agent whose approved dosing is based on an ex vivo platelet aggregation assay that uses such an anticoagulant. Additionally, Kereiakes et al. have recently reported that the high levels of platelet inhibition (>80 %), using PPACK as an anticoagulant and ADP (20 micromol) as an agonist, are more consistently achieved with the approved dosing regimen of eptifibatide. The antiplatelet effect of abciximab showed more interpatient variability, whereas the median inhibition of ex vivo platelet aggregation with the approved dosing regimen for tirofiban HCl was <80 % at almost all time points during drug infusion.
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Anaphylactoid reactions in patients receiving intravenously administered vitamin K have been reported in the literature. To summarize the known data on anaphylactoid reactions from administration of vitamin K, we reviewed all published and unpublished reports of this adverse reaction. Published reports were obtained through medline (1966--1999) and EMBASE (1971--1999) searches of the English language literature and review of references from identified case reports. ⋯ Anaphylactic reactions and case fatality reports were found even when intravenous vitamin K was given at low doses by slow dilute infusion. The pathogenesis of this reaction is unknown and may be multifactorial with etiologies including vasodilation induced by the solubilizing vehicle or immune-mediated processes. We conclude that use of intravenous vitamin K should be limited to patients with serious hemorrhage due to a coagulopathy that is secondary to a relative or absolute deficiency of vitamin K.