[Nitrate derivatives and hemostasis: fundamental concepts and clinical implications]

The nitrate derivatives in clinical usage have in vitro platelet inhibitor and therefore antiaggregant properties. As with EDRF, this effect is mediated, at least partially, by increased intraplatelet cGMP concentrations. There is a probable synergistic action with prostacyclin and its clinically stable analogues which exert their inhibitor effect via cGMP. The reality of an ex vivo inhibitor effect (after clinical administration) is more difficult to demonstrate. Some groups have reported prolonged bleeding times after administration of trinitrin. The interactions of nitrate derivatives with molecules used as platelet inhibitors, such as aspirin, require further study as do interactions with heparin (possible induction of resistance by a qualitative anti-thrombin III deficiency) and thrombolytics (increased clearance of tissue type plasminogen activator).