Effects of oral contraceptives, or lanosterol, on ADP-induced aggregation and binding of 125I-fibrinogen to rat platelets.

The aggregation to ADP and the binding of 125I-fibrinogen to platelets from rats treated with oral contraceptives or normal platelets treated in vitro with lanosterol were compared to their respective controls. Both types of platelets showed a significant increase in ADP-induced aggregation and in binding of fibrinogen, indicating that the effect of oral contraceptives could be partly due to increased levels of lanosterol in platelet membrane.