RESUMEN

Peripheral arterial disease (PAD) is by far the most common cause of intermittent claudication. This disease can greatly reduce the affected individual's walking capacity and can seriously affect daily life activities. Few therapeutic options are aimed at improving walking capacity. This was a randomized, doubleblind, placebo-controlled, multicenter trial, performed in 24 Italian centers. Two hundred seventeen patients with intermittent claudication (stages IIa and IIb of Fontaine's PAD classification) were randomly assigned to heparan sulfate (40 mg orally twice a day) or placebo for 6 months. The primary end-point was an increase in pain-free walking distance [initial claudication distance (ICD)] during the 24 weeks of treatment. The pain-free and the absolute walking distance (ACD) were monitored by standardized treadmill test at baseline and at 4, 12 and 24 weeks. The change in initial claudication distance during treatment, expressed as integrated change over time, was significantly greater with heparan sulfate than with placebo (306 +/- 494 vs. 250 +/- 510 meters x months, p = 0.019). Significantly fewer treated patients worsened during treatment (decreased initial claudication distance) compared with controls (9.1% vs. 19.6%; p = 0.027). Functional recovery in the most severely affected subgroup of patients (stage IIb of Fontaine's classification) was more clearly detected and significantly greater among treated than among control patients (absolute increase in ICD: 70 +/- 113 vs. 58 +/- 172 meters, p = 0.028; integrated increase: 304 +/- 422 vs. 208 +/- 503 meters x months; p = 0.004). Heparan sulfate appeared to increase the walking capacity of patients with intermittent claudication to a significantly greater extent than did placebo. The treatment was well tolerated.

Asunto(s)

RESUMEN

The acute (0.57 microg/kg i.v. in 2 hours) and long-term (0.57 microg/kg i.v. in 2 hours for 5 days over 4 weeks) effects of the PGE1 analogue alprostadil were studied in patients affected with intermittent claudication. Whole Blood Viscosity (WBV), Whole Blood Filterability (WBF), haematocrit (Htc) and fibrinogen plasma concentration, were studied together with P50, 2,3-diphosphoglycerate, and adenosine plasma levels. Moreover, in the long-term study, pain-free (PFWD) and maximal walking distance (MWD) were measured. Single alprostadil infusion induced an improvement in WBV, WBF, and oxygen transport, and an increase in adenosine plasma levels. Long-term alprostadil administration produced a decrease in WBV only, without significant changes in WBF, Htc, fibrinogen, P50, 2,3-diphosphoglycerate, also inducing a significant prolongation of PFWD and MWD. The possibility is suggested that pulse rises in adenosine plasma levels play a role in the effects of chronic alprostadil administration, maybe in a way similar to that observed in the phenomenon of ischaemic preconditioning,

Asunto(s)

RESUMEN

Defibrotide is a polydeoxyribonucleotide that possesses profibrinolytic and cytoprotective activities. These properties have been associated with its capacity to induce the release of prostacyclin and tissue plasminogen activator (t-PA) from endothelial cells. In the present study, the bolus administration of defibrotide in humans was able to induce (100-800 mg) a dose-dependent decrease in plasminogen activator inhibitor (PAI) (from 19.4 +/- 7.11 to 7.20 +/- 6.41 AU/mL) and an increase in t-PA (from 3.70 +/- 0.96 to 4.50 +/- 1.20 IU/mL) and in the stable prostacyclin derivative 6-keto-PGF1 alpha (from 18.83 +/- 3.83 to 26.75 +/- 8.48 pg/0.1 mL) in the venous blood. In a second part of the study, defibrotide has been shown to inhibit dose-dependently (10-100 microns) neutrophil activation in vitro: it decreased lysosomal enzyme release and superoxide anion and chemiluminescence production induced by the oligopeptide fMLP and the ionophores A23187 and ionomycin. The increase in extracellular calcium concentration from 0.5 to 2 mm antagonized the inhibitory effect of the drug. Defibrotide was able to reduce the cytosolic free calcium increase induced by specific stimuli by blunting calcium entry. Such an inhibitory activity of defibrotide was antagonized by theophylline, an adenosine receptor antagonist. The study confirms some pharmacological activities of defibrotide (release of t-PA and prostacyclin in vivo), and it also suggests that the compound blocks Ca2+ entry into the cells, possibly by interfering with the adenosine receptors.

Asunto(s)

RESUMEN

Twenty-four patients with vascular disorders, randomly divided into 3 dosage groups of 8 patients, were treated with a single oral dose of sulodexide (50, 100 or 200mg) and placebo. Tissue plasminogen activator (t-PA), plasminogen activator inhibitor (PAI-1) activity and antigen, euglobulin lysis time, α2-antiplasmin, plasminogen, fibrinogen, blood and plasma viscosity, and whole blood filtration rate were determined before administration and over the following 24 hours. Sulodexide significantly increased t-PA activity linearly with the dose over the range of 50 to 200mg. At the same time, it also significantly decreased the concentration of PAI-1 linearly and proportionally with the dose. No clear effects were observed on the other monitored parameters, although euglobulin lysis time and plasma viscosity showed a tendency to decrease after the administration of sulodexide. These results justify the clinical activity of sulodexide. Indeed, the concomitant increase of t-PA and decrease of PAI-1 activity and antigen might increase the natural fibrinolytic activity with a physiological potentiation, without other adverse effects. The known activity of sulodexide in decreasing plasma viscosity during long term treatment is, however, not immediately explicable by the single-dose effects.

RESUMEN

The efficacy and safety of Triflusal capsules given to patients at thrombogenetic risk because of platelet hyperaggregation were investigated in a controlled study involving 15 patients (9 males and 6 females, mean age 65.7 years) who were given 300 mg/day of Triflusal during the first 5 days and 600 mg/day during the following 5 days. Subsequently, after 7 days of wash-out all these patients received placebo for 10 days, one capsule for the first 5 days and 2 capsules for the following 5 days. The platelet antiaggregant activity of the drug was evaluated by means of Born's platelet activation test. Specific tests were also made to assess the effect of this substance on platelet release and the coagulation system. The safety was evaluated by measuring the most important clinical chemistry and clinical haematology indexes of haematopoietic, hepatic, renal and metabolic functions. Arterial blood pressure and heart rate values were also recorded. All the 15 patients completed the study. It was found that the Triflusal treatment led to a significant mean reduction of the indexes chosen as markers of thrombophilia or platelet hyperaggregation in vivo. It did not affect the normal haemostatic-coagulation process and was well tolerated by the patients. The subsequent placebo treatment did not induce any platelet antiaggregant effects.

Asunto(s)

RESUMEN

The pharmacokinetics and pharmacodynamics of dermatan sulfate (DS) was investigated in healthy volunteers (two groups, namely group A: 6 subjects, group B: 8 subjects). The subjects of group A received 100 mg of DS both i.v. and i.m. and the subjects of group B received 400 mg of DS both i.v. and i.m. in two different days. The resulting anticoagulant activities were assessed by the activated partial thromboplastin time (aPTT) and the pharmacokinetic parameters were calculated from the plasma concentrations of DS measured by a chromogenic assay. The plasma concentrations of DS were fitted by linear and non-linear elimination models (i.e. assuming that the drug elimination follows Michaelis-Menten kinetics). Some evidence of non-linear kinetics was given by the observation that the mean terminal half-life and clearance estimated by the linear model were not independent of the i.v. dose (0.83 +/- 0.1 and 1.74 +/- 0.21 hours and 4.94 +/- 0.64 and 2.67 +/- 0.27 l/h after 100 and 400 mg i.v. respectively. Moreover the mean half-lives estimated after i.m. administrations were much higher than the values estimated after the i.v. dose (2.03 +/- 0.74 and 3.54 +/- 1.3 hours after 100 and 400 mg) and linear models failed to fit simultaneously the DS plasma concentrations after both the administration routes. Using the linear model, the mean drug bioavailability after i.m. administration was estimated to be about 30% and 80% after the 100- and the 400-mg dose respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Asunto(s)

RESUMEN

In 6 normal volunteers given single oral doses of 250,500 and 1000 mg ticlopidine (T), the peak plasma level of unchanged drug was reached after about 2 h. There was no correlation between the plasma T level and its inhibitory effect on platelet function, expressed as % inhibition of ADP-induced aggregation. By means of HPLC and GC/MS significant concentrations of T were demonstrated in washed red cells, platelets and neutrophils, with a marked difference in the time course of the appearance of cell-associated drug. The time course of platelet-associated T very accurately fitted that of the antiaggregatory activity. After subacute oral administration (250 mg b.d. for 7 days), the maximum effect on platelet function was observed after 3 to 4 days, when a significant concentration of platelet-associated T had been reached. The pharmacological effect persisted as long as drug was detectable in platelet. An in vitro study strongly suggested that the antiaggregating effect was retained by treated washed platelets but not by treated plasma. It is suggested that the platelet compartment represents the pharmacological target of T via a specific uptake system.

Asunto(s)

RESUMEN

In a double-blind study, a single dose of 1600 mg cyclandelate or placebo was administered to 10 patients with cerebrovascular and/or peripheral vascular disease, and fibrinolytic activity was evaluated before and 1, 2, 4 and 6 h after treatment. Cyclandelate induced a reduction in euglobulin lysis time, an increase in tissue plasminogen activator concentration and a reduction in plasminogen activator inhibitor, alpha 2-antiplasmin and immunological fibrinogen concentrations, but no changes in antithrombin III and plasminogen concentrations were observed. After placebo administration no significant changes were observed. After treating two patients with 800 mg cyclandelate twice daily for 14 days, 1600 mg cyclandelate stimulated fibrinolysis for 8 h. It is concluded that the fibrinolytic activity of cyclandelate has implications for the treatment of cardiovascular complications of atherosclerosis.

Asunto(s)

RESUMEN

The authors report the results of a double-blind cross-over study on calcium dobesilate in which two groups of eight recent-onset type-II diabetics were treated either p.o. (1 g once daily) or i.v. (500 mg in 100 ml of physiological saline) with calcium dobesilate or with placebo. During oral administration of the drug, blood rheology and total fibrinolytic capacity were assessed by calculating euglobulin lysis time. In view of the evidence for a viscosity-lowering action of the drug (which had already been found in "long-term" studies) and of potentiation of fibrinolytic activity, intravenous treatment was started with the object of elucidating the possible mechanisms of action, evaluating at the same time other parameters concerning the functional fibrinolytic pathways. It has thus been possible to ascertain that the drug has "rheologic" activity, interferes with the function of endothelial cells by stimulating the release of tissue plasminogen activator and thus increases fibrinolytic activity while not interfering with the clotting function and not altering platelet beta-thromboglobulin secretion. These findings appear to confirm the possibilities for therapeutic use of calcium dobesilate which is thought to act on a variety of pathogenetic mechanisms involved in diabetic microangiopathy.

Asunto(s)

RESUMEN

In the past few years there has been increasing interest in the role of the vascular endothelium as an active modulator of biological responses. Endothelial cells exert antithrombotic activity by the release of prostacyclin [23] and adenine nucleotides [16], the availability on the cell surface of heparin-like substances [3], and thrombomodulin-mediated activation of protein C [8]. In addition, endothelium is involved in the regulation of fibrinolysis by releasing soluble factors, such as tissue plasminogen activator (tPA; [10]) and plasminogen activator inhibitor (PAI; [22, 11]), as well as in the control of vascular responsiveness by the production of smooth muscle relaxing and contracting factors. Endothelial cells have also been shown to synthesize and to express procoagulant activities [18]. Many data on endothelial cell functions has been obtained from two experimental models, namely endothelial cell cultures and perfused segments of animal and human vessels. Both are subject to methodological criticism since they only represent in part in vivo conditions, and the necessary experimental manipulations and laboratory procedures greatly modify the naturally occurring cellular functions. In order to overcome such difficulties as far as possible, a new in vivo model has been employed to provide easily assessable and reliable data on the properties of endothelial cells in man. A venous segment was isolated functionally by cannulating a dorsal vein in the hand and a cubital vein in the same arm. Changes observed ex vivo in blood from the cubital vein following infusion into the hand vein of an active drug, can mainly be attributed to its local effect on the venous wall. At the same time, a cubital vein in the other arm was cannulated in order to provide information to distinguish systemic from regional effects.

Asunto(s)

RESUMEN

The profibrinolytic activity of orally administered Mesoglycan was evaluated in 18 patients affected by impaired plasma fibrinolytic activity. Mesoglycan was administered by a single oral dose of 24, 48 or 72 mg on 1 day, and by repeated doses of 48 mg twice a day for 9 consecutive days. After the single administration all the fibrinolytic parameters were significantly and positively influenced with an order of magnitude and a duration of effects proportional to the dose employed. After the repeated administration, a constant and reproducible activation of the fibrinolytic system was observed without any interference with haemocoagulative parameters. These results confirm that Mesoglycan is endowed with a relevant profibrinolytic activity in man after oral administration. The pharmacological activity of Mesoglycan could possibly involve the liberation of a certain amount of plasminogen tissue activator.

Asunto(s)

Asunto(s)

RESUMEN

Deep venous thrombosis is a common disease with significant danger of both acute and chronic complications. Widely accepted therapies are based on anticoagulant (heparin and/or anticoagulant agents) or early fibrinolytic therapy. All these therapies frequently have severe side effects. Defibrotide is a new drug with antithrombotic and profibrinolytic activities but without anticoagulant activity and major side effects. To evaluate the efficacy of this drug against acute thrombophlebitis, we treated a group of 10 patients with 200 mg defibrotide intravenously three times a day for 15 days. Fibrinolysis parameters were monitored every other day. The indices of venous function by strain-gauge plethysmography and venous occlusion were evaluated every 7 days. The drug induced a significant improvement in plethysmographic indices and a significant profibrinolytic activity. Defibrotide-treated patients showed a fast disappearance of clinical and instrumental signs of thrombophlebitis. No side effects were reported during the study.

Asunto(s)

RESUMEN

Studies were carried out to investigate the effects of pentoxifylline on various hemorheological (whole blood, plasma and serum viscosity, erythrocyte filtrability, hematocrit), hemostasiological (blood coagulation and fibrinolysis: euglobulin lysis time, fibrinogen, plasminogen, alpha-2-macroglobulin, alpha-1-antitrypsin, antiplasmin; platelet function: beta-thromboglobulin), and hemodynamic factors (limb perfusion: rest and peak flow, time to peak flow; systemic blood pressure, heart rate). In addition, clinical efficacy was monitored in patients with claudication by assessing walking capacity under placebo controlled double blind cross over conditions. The investigations disclosed the positive influence of acute and chronic pentoxifylline administration on hemorheological, hemostasiological and perfusion parameters, most of the changes recorded being statistically significant. The clinical benefit of pentoxifylline (Trental 400) treatment was demonstrated by the significantly superior increase in walking capacity in comparison to placebo in the controlled study.

Asunto(s)

RESUMEN

A complete crossover trial was undertaken in six healthy volunteers to gain information on dose-effect responses to indobufen by assessing the intensity and duration of the effect of 3 single oral doses of the drug on platelet aggregation induced by threshold concentration of ADP and by 3 added doses of collagen. The results of the study confirm that the activity is dose-related and is reversible since 24 hours after administration it has practically disappeared. The effect of the same dose of indobufen differed significantly according to the amount of collagen added to plasma, whereas increasing doses of indobufen provoked a significantly more marked effect when the amount of inducer employed was the same.

Asunto(s)

RESUMEN

To compare the clinical and metabolic effects of a new diuretic uricosuric agent, tienilic acid, with those of hydrochlorothiazide, a multicentre double-blind trial was performed in 56 hypertensive patients. Twenty-eight patients were randomly assigned to take tienilic acid and 28 to take hydrochlorothiazide. The diuretic and anti-hypertensive actions of the two compounds were similar. No significant differences were observed between tienilic acid and hydrochlorothiazide in their effects on urinary and serum electrolytes, hepatic and renal function tests, and fasting lipids. The patients who received tienilic acid showed a significant fall in serum uric acid, mediated by the uricosuric effect. The availability of an agent combining diuretic, antihypertensive and hypouricemic effects offers promise in the treatment of arterial hypertension.

Asunto(s)