beta-lactam antibiotic-mediated changes in platelet reactivity and vascular endothelial functions

To evaluate vascular and platelet compatibility of intravenous administrati on of beta -lactam antibiotics, we assessed the effects of therapeutic conc entrations of ceftriaxone, aztreonam, and ceftazidime on platelet reactivit y to different agonists (sodium arachidonate, collagen and adenosine diphos phate) and on selected vascular endothelial functions (adenosine diphosphat ase activity, prostacyclin production and t-PA release). Ceftriaxone and, t o a lesser degree, aztreonam, enhanced platelet reactivity, evaluated as on set of platelet aggregating response, and increased thromboxane production to subthreshold concentrations of arachidonate. There was no modification i n platelet reactivity after ceftazidime treatment. Ceftriaxone and ceftazid ime, but not aztreonam, inhibited endothelial adenosine diphosphatase activ ity. Prostacyclin production and t-PA release were inhibited only by ceftri axone at high concentrations. While it is difficult to establish which mark er (platelet or endothelial functions) has more clinical reference in human vascular compatibility, it seems feasible to consider aztreonam the most c ompatible of the beta -lactams studied.