The effect of pentosan polysulphate (SP54) on the human fibrinolytic system.

In human volunteers the oral and subcutaneous (s.c.) administration of SP54 enhanced the fibrinolytic potential of plasma. When the effect was compared between exercise and s.c. administration of SP54 the latter was found to "peak" at about 3 hours and to have a more sustained effect than the exercise. Oral versus s.c. administration suggests that only about 10% of the SP54 reaches the circulation by the oral route. However, repeat SP54 oral dosage did not elicit any resistance to the daily response over a period of five days and suggests that the volunteers used in this study tolerated repeated use of the drug with no ill-effects. The source of the fibrinolytic enhancement is as yet not fully explained and a hypothesis is presented which suggests that very small elevations of t-PA in plasma can affect the fibrinolytic potential in the presence of forming fibrin but may remain undetected by conventional immunometric assays.