Prostaglandin I2 and the nitric oxide donor molsidomine have synergistic effects on thromboresistance in man.

1. In vitro synergistic effects of nitric oxide and prostaglandin I2 (PGI2) have been shown. Consequently we examined any potentiating effect of the nitric oxide donor molsidomine on the reduction in thrombogenicity produced by PGI2 in patients with peripheral vascular disease. 2. Thirty-six patients all with peripheral and also coronary artery disease were randomly allocated to receive PGI2 5 ng kg-1 min-1 for 6 h daily, 5 days a week for 5 weeks, alone (12 patients), with molsidomine 12 mg daily (12 patients) or molsidomine 12 mg daily alone (12 patients). 3. The effect of each treatment regimen was measured in terms of femoral artery platelet uptake and platelet survival after autologous 111Indium-oxine labelling. Molsidomine alone had no effect on platelet uptake or survival but in combination with PGI2 it significantly potentiated the decreased platelet uptake and prolonged platelet survival observed with PGI2 alone.