A comparative study of Dextran 70 and a sulphated polysaccharide in the prevention of postoperative thromboembolic complications

Sodium pentosan polysulfate efficacy as thromboprophylaxis agent in high-risk women following gynecological surgery

AIM

Sodium pentosan polysulfate (Na-PPS) is a plant-based agent that has similar action with low-molecular-weight heparin. It inhibits factor Xa, preventing blood clot formation. To date, its use in clinical practice as thromboprophylaxis agent is still limited. In addition, the efficacy and safety profile of this agent was not robustly reported globally, especially for countries with major Muslim population. We hypothesized that Na-PPS was equally effective as the standard thromboprophylaxis. We aim to compare the efficacy and safety of Na-PPS against standard agent (fondaparinux or enoxaparin).

METHODS

This was a randomized control, open-label trial. Women underwent major gynecological surgery were randomized to receive either subcutaneous 50 mg of Na-PPS twice daily or subcutaneous enoxaparin 40 mg once daily. Fondaparinux 2.5 mg once daily was given to Muslim women as an alternative to enoxaparin. The treatment was started 6 h postoperatively, for at least 3 days. All the patients received thromboembolic deterrent stockings. The primary efficacy outcome was venous thromboembolism up to 3 days postsurgery. The main safety outcomes were minor and major bleeding.

RESULTS

Among 109 participants, there was no incidence of venous thromboembolism. None of the women developed major bleeding. Minor bleeding was observed in 28.3% (15/53) and 5.4% (3/56) of Na-PPS and standard thromboprophylaxis group, respectively (P = 0.001).

CONCLUSION

Na-PPS was associated with increased risk of minor bleeding. There was insufficient data to conclude its efficacy as thromboprophylaxis. Further research is needed to evaluate Na-PPS safety as a standard thromboprophylactic agent.

Pharmacokinetics and Pharmacodynamics of Warfarin When Coadministered With Pentosan Polysulfate Sodium

The effect of pentosan polysulfate sodium on warfarin pharmacokinetics and pharmacodynamics was investigated in healthy subjects. Warfarin was titrated to an international normalized ratio between 1.4 and 1.8. Subjects continued their titrated dose of warfarin and received pentosan polysulfate sodium 100 mg or placebo every 8 hours for 7 days. The Cmax of R- and S-warfarin was approximately 840 to 890 ng/mL and 680 to 730 ng/mL, respectively, and was similar in the absence and presence of pentosan polysulfate sodium. The half-life for R- and S-warfarin was 52 to 56 hours and 36 to 40 hours, respectively. Prothrombin time, partial thromboplastin time, and the international normalized ratio for warfarin + placebo and warfarin + pentosan polysulfate sodium were comparable. The AUC(INR) indicated no treatment effect (P = .772); however, there was a period effect. Analysis of variance for the treatments by period indicated no treatment effect (P > .1). Adverse events were mild and included headache, epistaxis, and rash. Most adverse events were unrelated to treatment and were seen during warfarin titration. Pentosan polysulfate sodium did not affect warfarin pharmacokinetics or pharmacodynamics.

A phase I study of pentosan polysulfate sodium in patients with advanced malignancies

BACKGROUND

Pentosan polysulfate (xylanopolyhydrogensulfate) is a semi-synthetic sulfated heparinoid polysaccharide which has been used as an anticoagulant for nearly thirty years in Europe. It antagonizes the binding of bFGF to cell surface receptors and has thus been evaluated for antitumor activity in several animal models and human tumor cell lines. In two angiogenic models pentosan has been shown to inhibit bFGF stimulation of angiogenesis. Previous clinical studies have determined the coagulation effects of pentosan to be the dose-limiting toxicity.

PATIENTS AND METHODS

We conducted a phase I study designed to define the duration-limiting toxicity associated with progressive prolongation of a continuous intravenous infusion (three, five, and eight weeks). This study was not designed to escalate the dose of pentosan beyond that required to maintain the activated partial thromboplastin time (aPTT) between 1.8 and 2.2 times the baseline value.

RESULTS

Thirteen patients with advanced stage metastatic cancer were enrolled (median age 50 years, range 34 to 61 years). Four patients were treated in cohort #1 (three weeks of infusional therapy), five patients were treated in cohort #2 (five weeks of therapy), and four patients in cohort #3 (eight weeks of therapy). All patients experienced a progressive prolongation of their aPTT and PT. Furthermore, all patients experienced at least grade I thrombocytopenia. Other complications were, in general, mild. One patient developed grade III liver abnormalities while receiving the eight-week infusion and another patient developed grade IV thrombocytopenia while receiving the same regimen. One patient with colon cancer had stable disease for 24 weeks, while the remaining 12 patients had no objective evidence of response.

CONCLUSION

Pentosan was well tolerated when doses were adjusted for aPTT prolongations and a five-week cycle appeared to be the maximum tolerated duration of infusion (initially 4 mg/kg/day). One patient had stable disease, but there was no objective tumor response noted in the remaining 12 patients.

Anticoagulants in the prevention of venous thromboembolism

For 50 years, the key to successfully preventing venous thrombosis (VT) or pulmonary embolism (PE) among high-risk patients has been the judicious use of anticoagulants: first through full doses of oral anticoagulants and more recently through low-dose heparin prophylaxis. Low-dose heparin has become the standard of comparison for other preventive methods, since it is relatively safe and simple, its ability to prevent approximately 65% of the subclinical VT found by leg scanning after elective general surgery is well known, and recent meta-analysis of the many pertinent published clinical trials (large and small) strongly suggests a much greater benefit: a 65% reduction in the risk of postoperative death from major PE. In addition, there are trials that have also found low-dose heparin to be effective in general medical patients, although its value in this clinical setting is much less well documented. Although several effective approaches other than low-dose heparin are available, many of these tend to be either more cumbersome (intermittent external leg compression) or probably less powerful (graded pressure elastic stockings). There are situations where low-dose heparin prophylaxis fails, most obviously after orthopaedic surgery where the use of more complex regimens, including adjusted-dose heparin treatment and various schedules of warfarin prophylaxis, becomes appropriate. Recent progress has come from the intensive clinical exploration of various low molecular weight heparin fractions or fragments which appear to be effective after once daily administration to general surgical patients and show great promise of effectiveness and safety after hip surgery. The level of warfarin effect needed for VT prophylaxis has also been reinvestigated, with trials suggesting a need for less warfarin and a lower prothrombin time effect than was previously thought to be appropriate. Given that any attempts to minimize mortality from PE in hospital patients must rely on the widespread and systematic use of simple, safe, and cost-effective preventive methods, it is hoped that these advances will help move anticoagulant prophylaxis further out of the realm of clinical research and into that of common clinical practice.

Effect of the heparinoid pentosan polysulphate (SP 54) on the functional properties of cultured bovine aortic endothelial cells

The effect of the heparinoid, pentosan polysulphate (PP) on the proliferative behaviour of cultured bovine endothelial cells (EC) was examined. In addition, the toxicity of the drug towards EC, its influence on prostacyclin production and release, and on cell-associated plasminogen activator activity was determined. At a concentration of 10 micrograms/ml in the culture medium, PP exerted a growth promoting effect on EC. Increased cell numbers were accompanied by increased 3H-thymidine incorporation into cellular DNA compared with controls, however, final density of the cells was not affected. In contrast, at doses of 1 mg/ml the growth of EC was substantially slowed down. This finding did not reflect cell injury as shown by an unaltered release of 51Cr from the cells. Incubation of PP with EC had no influence on the prostacyclin release from the cells neither on the accumulation of the metabolite in the culture fluid over 24 hours nor on the releasing capacity upon stimulation with arachidonic acid. PP increased the cell-associated plasminogen activator activity in growing cells and counteracted in cultures at final density the inhibitory effect of serum on the intracellular plasminogen-activator activity. Our results suggest that stimulation of the fibrinolytic activity of the endothelium and a growth promoting effect for endothelial cells that may lead to faster coverage of small lesions could contribute to the antithrombotic potency of pentosan polysulphate in vivo.

The influence of a new low molecular weight sulphated polysaccharide from mussel broth (Org 30016) on haemostasis

The effect on haemostasis of a new low molecular weight sulphated polysaccharide (4300 dalton) from mussel broth (Org 30016) was investigated. In an APT time test system it had an anticoagulant effect corresponding to 30-40% of that of heparin. It had no antithrombin effect. It exerted its effect only in test systems containing phospholipids. It did not prolong haemostatic plug formation time in the rabbit mesenteric microcirculation as did heparin. Formation of ex vivo Chandler thrombi was significantly inhibited. The practical interest of the substance comes from the combination of an antithrombotic effect and little influence on primary haemostasis.

Comparison between commercial heparin, low molecular weight heparin and pentosan polysulfate on hemostasis and platelets in vivo

The effect of commercial heparin (MW 15000; 60 U/kg), low molecular weight heparin (MW 4500, 60 U/kg), sodium pentosan polysulfate (PZ-68) in doses of 0.5, 1, 2 and 5 mg/kg and 1 mg/kg combined with dextran 70 (0.5 g/kg) on microvascular hemostasis and platelet activity in vivo was investigated in the microcirculation of rabbit mesentery and ear chamber, respectively. Low molecular weight heparin did not alter the hemostasis: nonetheless, commercial heparin and PZ-68 interfered with the hemostatic mechanism by decreasing the stability of the hemostatic plug. This abnormality was more apparent in the venular than in the arteriolar system. Both heparins exhibited a trend towards an increase in platelet reactivity and the reverse was observed following the administration of PZ-68.

Prophylaxis of deep vein thrombosis in patients with fracture of the femoral neck: a prospective comparison between dextran and a sulphated polysaccharide

A prospective and randomized study of 100 patients with fracture of the femoral neck was carried out. The aim was to compare the thromboembolic prophylactic effect of dextran 70 and a sulphated polysaccharide, PZ 68. Deep vein thrombosis was diagnosed using the 125I-fibrinogen test and phlebography, and pulmonary embolism with a perfusion and ventilation scan. The number of thromboses and emboli did not differ significantly between the two groups. However, there was a general tendency for predominance of thrombosis on the operated side. Six patients were excluded in the PZ 68 group because of major haemorrhage.