Effects of latamoxef on in vitro and ex vivo thromboxane A2 generation in human platelets

Although beta-lactam antibiotics cause similar platelet abnormalities in vitro and in vivo, it is still unclear whether the mechanism(s) leading to the defects in both conditions are the same. The present work compared in vitro and ex vivo effects of latamoxef (LMOX) on aggregation and thromboxane (TX)A2 generation, determined as TXB2 generation. In the in vitro systems, LMOX interfered with both responses induced with all agonists tested (ADP, collagen and thrombin). Furthermore, although LMOX did not suppress arachidonic acid (AA)-induced TXB2 generation, it significantly suppressed the aggregation. In ex vivo systems performed with four healthy subjects, LMOX administration clearly suppressed the ADP-induced responses, but not the responses induced with the other agonists or AA. These differences observed in vitro and ex vivo are discussed from the viewpoint of different action mechanisms of LMOX under the two conditions.