Intravenous urokinase in acute myocardial infarction

Analytic Review: Thrombolytic Therapy in Acute Myocardial Infarction

The salvage of myocardium in the setting of acute myocardial infarction has long been a goal of physicians involved in the care of patients with coronary artery disease. Understanding the role of thrombosis in the pathogenesis of acute myocardial infarction has led the way to an entirely new approach to the treatment of this entity. Thrombolytic therapy has now become a widely used form of treatment with encouraging results. Both intravenous and intracoronary administration of thrombolytic agents have been shown to promote recanalization of acutely occluded coronary arteries. Results of studies using the clot-specific agent, tissue plasminogen activator, intravenously have been most encouraging; successful reperfusion has been obtained in approximately 70% of patients treated. In addition, a recent large-scale trial has shown a reduction in morbidity and mortality with the early use of thrombolytic agents.

Ongoing trials should help delineate the precise role and timing of these agents as the initial form of therapy for acute myocardial infarction. Other issues that remain unresolved are the frequency of restenosis and the role of percutaneous transluminal coronary angioplasty in addition to thrombolytic therapy in the treatment of acute myocardial infarction.

Thrombolytic Therapy: A Comprehensive Review of its Use in Clinical Medicine—Part I

In the first part of this comprehensive review of thrombolytic therapy in clinical medicine, we begin with a brief history of fibrinolysis, followed by a review of the components of die endogenous fibrinolytic system and the currently available plasminogen activators. An in-depth examination of thrombolysis in treatment of acute myocardial infarction follows, Including recommendations for management based on available clinical trial data. New developments in thrombolytic therapy are also discussed.

Novel technique for the treatment of large subcapsular renal hematoma: combined use of percutaneous drainage and urokinase injection

PURPOSE

To evaluate the efficacy and safety of combined use of percutaneous drainage and urokinase injection to treat patients with large subcapsular renal hematoma.

METHODS

We retrospectively analyzed the data of 20 patients with large subcapsular renal hematoma who were treated with percutaneous drainage and urokinase at our institutes between 2002 and 2010. Percutaneous drainage of the hematoma was performed after bleeding stopped. Then, urokinase was injected into the hematoma cavity per our protocol every 3 days. During the treatment and follow-up period, the diameter of hematoma was assessed by ultrasonography and enhanced computed tomography (CT) in all cases. Complete blood count, serum creatinine and blood pressure were evaluated as well. Follow-up periods ranged from 12 to 60 months (mean 24.1 ± 11.5 months).

RESULTS

Percutaneous renal hematoma drainage combined with urokinase injection was successfully performed in all the patients. After sufficient drainage, all of the patients were free from their symptoms. The average time to pain relief was 10.8 ± 2.1 days after percutaneous drainage, and the total duration of drainage was 28 ± 5.1 days. Relative to baseline, there was reduction in the diameter of hematoma evaluated by the enhanced CT scan after treatment (from 11.7 ± 3.1 to 2.8 ± 1.0 cm). During long-term follow-up, active bleeding, hypertension, renal function impairment or infectious complications were not found.

CONCLUSIONS

This study revealed that combined use of percutaneous drainage and urokinase injection was a safe and effective treatment for patient with large subcapsular renal hematoma.

Effect of very early intravenous streptokinase infusion in patients with evolving myocardial infarction

The effect of very early infusion of 1.5 X 10(6) U of streptokinase intravenously was studied in 29 patients with nitroglycerin-resistant chest pain and ST-segment elevation. Infarct size was estimated from maximal LD1 isoenzyme levels, and the diagnosis confirmed by CK-MB determination. Thrombolytic therapy was started within 1 hour of pain onset in 11 patients (group A), between 1 and 2 hours in 10 (group B), and later than 2 hours in eight patients (group C). Marked differences appeared between the groups. Thus, three patients in group A and one patient in group B did not develop infarction, all had critical LAD stenoses. Three patients in group C died in shock without bleeding. Further, the average maximal LD1 values in the 22 patients who survived their infarction differed significantly between the groups, and were 12.6, 19.1 and 36.2 mu kat/l in groups A, B and C, respectively. In conclusion, very early intravenous streptokinase infusion probably reduces myocardial necrosis, and possible prevents infarction in some patients.

Risk of intracranial haemorrhage with bolus versus infusion thrombolytic therapy: a meta-analysis

BACKGROUND

Although thrombolytic therapy given by bolus injection seems to be as effective as infusion over 60-90 min, no single trial has been adequately powered to detect clinically important safety differences between the two strategies. We did a meta-analysis to find out whether bolus administration of thrombolytics is associated with an increased frequency of intracranial haemorrhage.

METHODS

We identified randomised trials comparing bolus with infusion thrombolytic therapy by a search of electronic databases, reference lists, and conference proceedings. Odds ratios for primary intracranial haemorrhage, non-haemorrhagic stroke, mortality, and reinfarction were calculated for each trial and were combined in a fixed-effects model.

FINDINGS

Seven trials, involving a total of 103,972 patients, met our inclusion criteria. Bolus treatment was associated with an increased risk of intracranial haemorrhage compared with infusion (0.8 vs 0.6%; odds ratio 1.25 [95% CI 1.08-1.45]; p=0.003). The increased risk was most striking in trials comparing bolus with infusion administration of the same agent (1.75 [1.32-2.33], p=0.0001), but was also evident in trials comparing a newer-generation bolus agent with standard infusion therapy (1.25 [1.03-1.50]; p=0.02). The rates of non-haemorrhagic stroke (0.94 [0.81-1.09]), 30-day mortality (1.01 [0.97-1.06]), or reinfarction (1.04 [0.97-1.11]) did not differ between the two strategies.

INTERPRETATION

The increased risk of bolus thrombolytic treatment seems to be primarily associated with the method of administration rather than properties of the agents. Although the increased risk of intracranial haemorrhage is small, physicians should balance this risk against the putative benefits of easier administration with no difference in mortality or reinfarction.

Thrombolytic therapy in acute myocardial infarction

Early reperfusion of thrombotically occluded coronary arteries by thrombolytic therapy has become a routine option in initial therapy of acute myocardial infarction. Many efforts have been made to improve the biological properties of thrombolytic agents in terms of fibrin specificity, plasma half-life and resistance to natural plasma inhibitors, to improve adjuvant therapy and to shorten the 'pain to reperfusion' time. Numerous randomised, multicentre trials have analysed the benefit of the various thrombolytic agents and regimens, which has enabled the creation of a 'current standard of therapy'. This review presents an update on available thrombolytic agents, their biochemical and pharmacological properties and results from clinical trials.

Saruplase in Myocardial Infarction

Saruplase is an unglucosylated single-chain recombinant urokinase-type plasminogen activator. Dose finding studies in patients with acute myocardial infarction indicated that a dose of 80 mg of saruplase, given as a bolus of 20 mg and iv infusion of 60 mg in one hour, led to excellent patency figures.Saruplase is most effective when combined with a bolus of 5000 IU heparin followed by an iv heparin infusion for at least 24 hours.When saruplase is compared to other thrombolytic agents (streptokinase, alteplase, urokinase), it becomes apparent that its profile is excellent. Early patency rates are at least comparable to alteplase. Further reocclusion rates of saruplase after one day are lower than those of streptokinase and alteplase. Patency rates 24-72 hours after start of medication are comparable between saruplase and urokinase.The large database in over 6000 patients shows that saruplase, in comparison to the other thrombolytic agents, is safe. Its bleeding complication rate is significantly lower than streptokinase, and a trend to lower in-hospital mortality is observed when compared to urokinase.Summarizing, when comparing to the presently available thrombolytic agents, saruplase is a fast acting, effective and safe thrombolytic agent.

A Double-Blind Multicenter Comparison of the Efficacy and Safety of Saruplase and Urokinase in the Treatment of Acute Myocardial Infarction: Report of the SUTAMI Study Group

Background: Urokinase or two-chain urokinase-type plasminogen activator has been shown to be effective in the treatment of acute myocardial infarction. Its parent molecule, single-chain urokinase-type plasminogen activator (scu-PA), unlike urokinase, can selectively activate fibrin-bound plasminogen. The induced clot lysis is amplified by plasmin-triggered conversion of scu-PA to urokinase and by further plasmin generation. The aim of our study was to compare the efficacy and safety of recombinant unglycosylated scu-PA, or saruplase, and urokinase at doses considered optimal in patients with acute myocardial infarction within 6 hours of onset of pain. Methods and results: In a double-blind trial 543 patients were randomized to saruplase (20 mg bolus + 60 mg/hr) or urokinase (1.5 million unit bolus + 1.5 million units/hr). Primary endpoint: The patency rates at 24-72 hours were 75.4% (95% CI 70.3-80.5%) for saruplase and 74.2% (95% CI 69.0-79.4%; P = 0.77) for urokinase. Secondary endpoint: The incidence of bleeding events in both groups was 10.7%. There were three hemorrhagic strokes in the saruplase group (ns). Other efficacy and safety evaluations: Apart from the generation of more fibrinogen degradation products under saruplase, the changes in hemostatic parameters did not differ. Hospital mortality was 4.4% for saruplase and 8.1% for urokinase. This nonsignificant difference was maintained for 1 year. Conclusion: The efficacy and safety of saruplase and urokinase in the regimens used are very similar.

Pharmacokinetics and hemostatic effects of saruplase in patients with acute myocardial infarction: comparison of infusion, single-bolus, and split-bolus administration

Saruplase, or unglycosylated, single-chain urokinase-type plasminogen activator (scu-PA) selectively activates fibrin-bound plasminogen, and is subsequently converted to its two-chain derivative tcu-PA (urokinase) by plasmin. The efficacy of a 20 mg IV bolus followed by an infusion of 60 mg over 1 hour (standard regimen) has been demonstrated in acute myocardial infarction (AMI). The Bolus Administration of Saruplase in Europe (BASE) study compared the efficacy of standard therapy, single bolus (80 mg), and split bolus (2 x 40 mg at 30-minute intervals) in AMI. In a substudy of BASE, the pharmacokinetics of total u-PA activity (amidolytic activity after plasmin treatment), high molecular weight (HMW) u-PA antigen, and tcu-PA activity were compared in patients receiving standard therapy (n = 4), single bolus (n = 4), or split bolus (n = 5). Total u-PA activity and HMW u-PA antigen were similar. The maximum concentration (C(max,), mean +/- SD) of total u-PA activity was 2.2 +/- 0.3 microg/mL after standard therapy, 16.3 +/- 3.9 microg/mL after single bolus, and 8.2 +/- 1.6 ug/mL after split bolus. The area under the concentration versus time curve (AUC) values of total u-PA activity were 1.7 +/- 0.1 microg/mL*h (standard therapy), 4.0 +/- 0.9 microg/mL*h (bolus), and 3.0 +/- 0.7 microg/mL*h (split bolus). The dominant initial half-lives (t(1/2) alpha) were 7.1 +/- 1.1 minutes (standard), 8.8 +/- 0.8 minutes (bolus), and 5.1 +/- 2.1 minutes (split bolus). Maximum plasma concentrations of of tcu-PA activity were observed at 5.2 +/- 7 minutes (standard), 21 +/- 10 minutes (bolus), and 42 +/- 2 minutes (split bolus). C(max) was lowest after standard therapy (0.6 +/- 0.3 microg/mL), highest after bolus (4.2 +/- 2.2 microg/mL), and approximately twice as high as standard therapy after split bolus (1. 3 +/- 0.8 microg/mL). After standard therapy the mean fibrinogen concentration decreased gradually from approximately 300 mg/dL to 70 mg/dL at 90 and 120 minutes. After a single bolus the fibrinogen concentration decreased below the limit of quantification within 30 minutes and remained there for at least 120 minutes. Directly after the second 40 mg dose of the split bolus, the fibrinogen levels had an accelerated and more pronounced decrease to approximately 65 mg/dL at 90 and 120 minutes. A single bolus results in very high early total u-PA activity, which accelerates the appearance of tcu-PA activity and fibrinogen consumption. The pharmacokinetics and hemostatic effects of the split-bolus regimen are more comparable with those of standard therapy.

Comparison of double bolus urokinase versus front-loaded alteplase regimen for acute myocardial infarction. Thrombolysis in Myocardial Infarction in Korea (TIMIKO) study group

This study was performed to compare the double bolus urokinase regimen with the front-loaded alteplase regimen for acute myocardial infarction. Double bolus urokinase is an easy, safe, and effective thrombolytic regimen with comparable results to standard front-loaded alteplase in acute myocardial infarction.

Bolus Administration of Saruplase in Europe (BASE), a Pilot Study in Patients with Acute Myocardial Infarction

To study the safety and efficacy of the thrombolytic agent saruplase as a bolus, the angiographic and clinical outcomes of three bolus regimens were investigated in a pilot study conducted in 192 patients with an acute myocardial infarction and were compared with the standard regimen. Fifty-two patients received a double bolus of 40 mg and 40 mg after 30 minutes, 51 patients a bolus of 80 mg, and 36 patients a bolus of 60 mg. Fifty-three patients received the standard regimen (a bolus of 20 mg and 60 mg IV infusion over 1 hour). At 60 minutes TIMI 2 and 3 flow were, respectively, 9.6% and 61.5% with the 40/40-mg bolus, 15.7% and 51.0% with the 80-mg bolus, 16.7% and 30.6% with the 60-mg bolus, and 7.5% and 54.7% with the standard 20/60-mg infusion. At 90 minutes TIMI 2 and 3 flow improved to 9.6% and 73.1%, 15.7% and 56.9%, 13.9% and 36.1%, and 5.7% and 71.7%, respectively. The primary endpoint, persistent patency (TIMI 2 + 3) at 24-45 hours, was seen in 69.2%, 64.7%, 44.4%, and 67.9% of patients who had no rescue PTCA, respectively. Inclusion in the 60-mg bolus group was prematurely stopped because of their low patency rates. The 40/40-mg bolus group had the highest mortality rate (13.5%), whereas the 60-mg bolus group had no deaths. Other adverse event rates were similar in the four groups. This clinical outcome is highly influenced by rescue PTCA of patients with insufficient TIMI flow. This pilot study indicates that in patients with an acute myocardial infarction, a double bolus of 40/40 mg resulted in the highest patency but also had the highest complication rate. The 80-mg single bolus is an attractive alternative for further evaluation because of its acceptable patency and event profile, and its easy form of administration.

Expansion of a Haematoma after Urokinase Thrombolysis of Superior Sagittal Sinus Thrombosis

Thrombosis of the superior sagittal sinus may result in significant morbidity and recently up to 20% mortality. Primary treatment has consisted of anticoagulation and methods for controlling increased intracranial pressure. The development of interventional neuroradiologic techniques has enabled infusion of thrombolytics at the clot.

We describe a woman with a cerebral haemorrhage due to a thrombosed superior sagittal sinus.

Her decreased level of consciousness and increasing hemiparesis prompted direct thrombolytic therapy (urokinase). Flow was restored in the occluded sinus, but an acute expansion of the haematoma an hour after conclusion of the infusion resulted in temporary worsening of her neurologic deficits.

Although the ultimate outcome was satisfactory, the possibility of further intracranial bleeding must be balanced against the risk of death with conservative therapy.

Effects of increased liver blood flow on the kinetics and dynamics of recombinant tissue-type plasminogen activator

OBJECTIVE

To investigate the influence of increased liver blood flow on the pharmacokinetics and pharmacodynamics of recombinant tissue-type plasminogen activator (rt-PA) and to study the changes in endogenous urokinase-type plasminogen activator (u-PA).

METHODS

This open, randomized, crossover trial was carried out in a clinical research unit. Eight healthy, nonsmoking volunteers received linear infusions of 24 mg rt-PA and 92 mg indocyanine green over 160 minutes. Sixty minutes after the infusions were started, the subjects consumed a standardized meal to increase liver blood flow on one occasion and abstained from taking food on the other occasion. Plasma concentrations of indocyanine green, tissue-type plasminogen activator (t-PA) antigen, t-PA activity, total u-PA antigen, plasmin-activatable single-chain u-PA (scu-PA), active two-chain u-PA (tcu-PA), fibrinogen, total fibrin, and fibrinogen/fibrin degradation products (TDP), and alpha 2-antiplasmin were measured.

RESULTS

After the consumption of the meal, the area under the curve (AUC) was 35% (95% confidence interval [CI]: 25%, 43%) lower for indocyanine green, 15% (CI: 6%, 24%) lower for t-PA antigen, and 11% (CI: 2%, 19%) lower for t-PA activity compared to the AUC after subjects abstained from food. No changes were observed in fibrinogen, TDP, or alpha 2-antiplasmin concentrations that were attributable to the intake of food. The infusion of rt-PA caused a fivefold increase in the concentration of active tcu-PA and a concomitant decrease in scu-PA concentrations by more than 50%.

CONCLUSIONS

Increased liver blood flow results in an increase in t-PA clearance. The conversion of the inactive zymogen scu-PA to the active tcu-PA is increased by an infusion of rt-PA, but total u-PA antigen concentrations remain unchanged.

Immediate hemodynamic effects of thrombolytic therapy on the ischemic myocardium

Thrombolytic agents are used to restore coronary artery perfusion and limit the size of a myocardial infarction. The systemic effects of these drugs, streptokinase (SK), urokinase (UK), and recombinant tissue plasminogen activator (rtPA), have been studied extensively. Although their effects on rheology and late myocardial performance have been well-documented to date, there have not been any studies evaluating the acute hemodynamic consequences of thrombolytics immediately after administration. In this report we use an isolated Langendorf rodent heart preparation to evaluate the acute hemodynamic effects of thrombolytic therapy on both the normal and the ischemic myocardium. We quantified performance by documenting cardiac output, coronary blood flow, and blood pressure. Although each thrombolytic agent significantly transiently impairs cardiac performance, differences in effect between the agents were statistically insignificant. This was also the case with both the normal as well as the ischemic myocardium. The results of this study would not support favoring the use of one of these agents over the other with regards to primary myocardial performance.

Guidelines for general practitioners administering thrombolytics

Acute myocardial infarction (AMI) recognises no boundaries, and the patient's greatest need occurs at the interface between primary care and hospital system. Ideally, the general practitioner, if summoned, should be able to provide resuscitation, analgesia with opiates, and thrombolytic therapy. Thrombolytics should certainly be given to eligible patients by the general practitioner if an hour could be saved by so doing. Optimising the risk-benefit ratio for thrombolytic therapy given in the community is a challenge to clinical judgement. Experience with this potent treatment is best obtained under a degree of supervision, which could take the form of an audit of the prehospital management of suspected AMI. With prehospital administration of thrombolytic therapy at the first opportunity, the chances of saving a life are better than 1 in 10, while the excess risk of a disabling stroke is about 1 in 1000.

Thrombolytic therapy of acute myocardial infarction

Considering the enormous increase in the use of thrombolytic therapy over the last decade, many of the early concepts of thrombolytic therapy have proved to be remarkably robust. Early and sustained restoration of coronary patency remains the ultimate goal. Streptokinase is still extensively used despite evidence that alteplase may, under some conditions, be more effective. Aspirin is of proven efficacy, heparin is important with alteplase but less so with streptokinase. The benefits of early thrombolysis, even if this means pre-hospital administration, have been repeatedly confirmed. On the debit side, more effective thrombolysis seems to go hand in hand with increased bleeding risk, and primary angioplasty seems to be emerging as a viable alternative in high risk patients. More effective regimens tend to be more complex, and the proportion of eligible patients receiving thrombolytic therapy is still relatively low. Better early diagnosis, by methods independent of the electrocardiogram, and simplified but effective treatment regimens using improved thrombolytic agents are likely developments in the near future.

Frequency of inclusion of patients with cardiogenic shock in trials of thrombolytic therapy

The purpose of this study was to determine the extent to which patients with cardiogenic shock have participated in trials of thrombolytic therapy, to examine factors associated with their exclusion from these trials, and to summarize data on the efficacy of thrombolysis in these patients. Previous publications were searched for all randomized, controlled studies involving the use of thrombolytic medications used in the treatment of acute myocardial infarction. Data were abstracted for year of trial publication, performance location, sample size, maximal allowable delay between symptom onset and treatment, and exclusion criteria. Of the 94 trials included in the analysis, 22% included patients with cardiogenic shock, 37% excluded them, and the remainder contained no information on their inclusion or exclusion. Only 2 trials provided data on the efficacy of thrombolytic therapy in patients with cardiogenic shock. Multivariate analysis revealed that studies conducted exclusively in the U.S. were significantly more likely to exclude patients in cardiogenic shock than those conducted outside of the U.S., as were studies that excluded patients with a previous myocardial infarction, studies published more recently, and smaller trials. Patients with cardiogenic shock have frequently been excluded from clinical trials of thrombolytic agents. As a result, data on the efficacy of thrombolytic agents in these patients is extremely limited.

Febrile reaction associated with urokinase

Urokinase is an endogenously produced human proteolytic enzyme used to treat many thrombotic disorders. A 54-year-old man with recurrent myocardial infarction experienced fever during intracoronary urokinase infusion into a saphenous vein graft; the fever resolved after discontinuation of the infusion. After excluding all other possible etiologies of fever, urokinase was determined to be the cause. Several studies indicated that this reaction may be associated with urokinase infusion, but it is actually recognized by few individuals. This is the first published case report of the adverse event to our knowledge.

Pharmacological management of acute myocardial infarction

The routine medical management of patients with acute myocardial infarction (AMI) has undergone major changes in the last decade. Several large-scale trials have firmly established the effectiveness of thrombolytic therapy, beta blockers, and aspirin in the treatment of AMI. The critical issues include reducing myocardial oxygen demand and restoring adequate blood supply to the ischemic regions of the myocardium. As a result, the ability to intervene in patients with AMI has improved significantly. The purpose of this review is to discuss briefly the results of major trials of primary and secondary pharmacological intervention which had a direct impact on the care of patients with AMI. It concludes with current recommendations for the management of patients with AMI.

Coronary thrombolysis. Comparative effects of intracoronary administration of recombinant tissue plasminogen activator and urokinase

We employed a canine model of coronary thrombosis, induced by injection of radioactive blood clot, via a catheter placed in the left anterior descending coronary artery, to compare effects of intracoronary administration of recombinant tissue plasminogen activator (rtPA) and urokinase (UK) on rate and extent of coronary thrombolysis. Two doses of UK, 15,000 U/kg (UK15) and 30,000 U/kg (UK30) and two doses of rtPA, 0.25 mg/kg (rtPA.25) and 0.75 mg/kg (rtPA.75) were given. Drugs were infused over 45 min. Compared with the other regimens, rate and extent of coronary thrombolysis were significantly increased with rtPA.75. Also, despite a much higher dose of UK, coronary thrombolysis was similar with UK30 and rtPA.25. Compared with UK15, rate and extent of coronary thrombolysis were increased with rtPA.25. These results indicate that intracoronary administration of rtPA is superior to intracoronary UK in inducing thrombolysis.

Advances in thrombolytic therapy

Alteplase and saruplase are more fibrin-specific thrombolytic drugs than anistreplase. These and the thrombolytic drugs of the first generation (streptokinase and urokinase) have shortcomings and limitations. The prolonged intravenous maintenance infusions have been replaced by a bolus injection, accelerated infusions, or the combined intravenous administration of thrombolytic agents. Numerous truncated alteplase or saruplase molecules have been constructed by deletion and domain substitution or hybrids made of the two molecules without gaining in thrombolytic potency. Recombinant staphylokinase and plasminogen activator from bat saliva have some interesting properties and are being investigated. Thrombus-targeted thrombolytic drugs were constructed using monoclonal antibodies against fibrin fragments or against epitopes of activated platelets. Fibrin-specific thrombolytic drugs require the concomitant use of a potent antithrombotic drug to prevent reocclusion. Whether hirudin or synthetic thrombin inhibitors are superior to heparin and whether novel antiplatelet agents, including monoclonal antibodies to platelet receptors and disintegrins, are more effective than aspirin is under clinical investigation. The place of stable analogues of prostacyclin during thrombolytic treatment is still unsettled.

Pharmacology of fibrinolysis

Fibrinolytic therapy has an expanding role in the treatment of many thromboembolic disorders. Four fibrinolytic drugs are currently marketed: streptokinase, anisoylated plasminogen-streptokinase activator complex, urokinase, and recombinant human tissue-type plasminogen activator. All 4 of these drugs activate the fibrinolytic system by converting plasminogen to the active enzyme, plasmin. Plasmin present in the confines of a thrombus degrades fibrin and dissolves the thrombus. Plasmin free in the circulation degrades fibrinogen and other coagulation factors. All 4 of the currently available fibrinolytic agents are capable of initiating thrombus dissolution and, at doses currently recommended, cause degradation of fibrinogen and predispose to bleeding complications. Differences in the mechanisms of plasminogen activation among the available agents provide a theoretical basis for postulating the superiority of one agent over another in clinical practice. However, the relative roles of these agents in treatment of thromboembolic disorders depend on the outcome of properly designed and executed clinical trials.

Ultrarapid urokinase in hemodialysis access occlusion

Over a 3-month period, 14 consecutive hemodialysis access occlusions were treated with 1-1.25 million IU of urokinase (UK) delivered at a rate of 20,000 IU/min. After systemic heparin administration, lytic infusion via the crossed-catheter technique was performed with use of pediatric microdrip pumps, with determination of success within 1 hour. Patency was established radiographically in 11 of 14 occlusions, for a 79% immediate success rate. At 285-day mean follow-up, 9% (one of 11) remained patent without further radiologic or surgical intervention; graft survival was 64% (seven of 11). No significant complications occurred with use of ultrarapid UK. The 1-hour outpatient procedure safely allowed for rapid triage between surgical and radiologic intervention, minimal catheter manipulation or physician dependency, shorter duration compression of any bleeding venipuncture sites during UK administration, and greater patient comfort because of shortened procedure times.

Experiences in intravenous urokinase treatment of 100 acute myocardial infarction patients

From 1980 to 1990 we treated 100 cases of AMI with i.v. urokinase (UK). According to the way of management and the dosage administered all these cases were divided into three groups: first stage of small dosage, second stage of trial big dosage, and third stage of comprehensive dosage. 36 patients of the first stage were treated with small dosage, 1-20,000 U b.i.d. for 1 week. 75% of the UK-treated and only 17% of the control group obtained relief of pain. Decrease of elevated ST reaching base line was 50 vs 8%, and FDP increased in 94%. 22 patients of the second stage were undergoing trial of big dosage. They were subdivided into larger dosage (more than 800,000 U) and smaller dosage (less than 300,000 U) groups. From the larger dosage group, 2 patients showed definite sign of recanalization, but unexpectedly 2 patients died of cardiac rupture. Since the recanalization rate of larger dosage group was 42.9%, but no case showed sign of recanalization in smaller dosage group, we are of the opinion that the dose of 800,000 U is rational for patients with symptoms' onset less than 3 h. Cardiac rupture was thought to be mostly due to reperfusion injury. Thus we designed the third stage of comprehensive dosage of UK. In this stage we used different dosage of UK and different ways of administration in 52 patients, based on the different symptoms' onset, so as to bring the effect of UK in full play. The aim of using UK is chiefly fibrinolysis as well as improvement of blood viscosity.(ABSTRACT TRUNCATED AT 250 WORDS)

Urokinase-mediated thrombolysis: a dose-response relationship in cats. Work in progress

A cat model was developed to study thrombolytic agents. The infrarenal aorta was surgically exposed, all side branches were ligated, and both ends of the segment were occluded. After preformed clot was injected into the segment, proximal flow was restored and a distal stenosis was created. Urokinase was infused at rates varying from 4,000 to 250,000 U/h. Amount of remaining clot was quantified every 15 minutes with cine angiography. Pre- and postinfusion measurements of prothrombin time, partial thromboplastin time, thrombin time, and levels of fibrinogen and fibrin degradation products were obtained. A graph of thrombolysis rate versus infusion rate was obtained yielding maximal thrombolytic activity at 126,000 U/h and 90% of maximal activity at an infusion rate of 70,000 U/h. Levels of fibrin degradation products did not change. Prothrombin, partial thromboplastin, and thrombin times increased with increasing infusion rates, leveling off at 100,000 U/h, while fibrinogen levels decreased, with a plateau at 50,000 U/h.

Half-life of single-chain urokinase-type plasminogen activator (scu-PA) and two-chain urokinase-type plasminogen activator (tcu-PA) in patients with acute myocardial infarction

The pharmacokinetics of urokinase (two-chain urokinase-type plasminogen activator, tcu-PA) and single-chain urokinase-type plasminogen activator (scu-PA) were studied in 20 patients with acute myocardial infarction (AMI). Ten consecutive patients received 2.5 million units tcu-PA by bolus injection within 5 min during the first 6 h after AMI (group I). Ten further consecutive patients received 250,000 U tcu-PA within 5 min, followed by 4.5 million U scu-PA by intravenous infusion over 40 min (group II). An enzyme immunoassay was developed for urokinase antigen determinations, and a fibrin plate assay for determinations of fibrinolytic activity was applied. Using a 3-compartment model, in group I 98% of urokinase antigen were cleared with a half-life of 60.8 min. After scu-PA, urokinase antigen was cleared with half-lives (area under the curve in parentheses) of 6.9 min (74.8%), 26.5 min (23.6%), and 329.7 min (2.2%). The half-disappearance times of fibrinolytic activity were 18 and 8 min in group I and II, respectively. A more pronounced decrease of plasminogen was observed after tcu-PA.

Safety and efficacy of urokinase during elective coronary angioplasty

Eighty-nine of 462 patients were treated with adjunctive urokinase during elective percutaneous transluminal coronary angioplasty (PTCA), 26% for unstable angina, 34% for intracoronary thrombus, 27% for intimal dissection, 10% for abrupt closure, and 3% for saphenous vein graft embolism. The 80 patients treated before abrupt closure (group A) were compared with 167 patients with similar profiles who did not receive urokinase (group B). Procedural success rates were similar. Adverse cardiac events (abrupt closure, myocardial infarction, emergency coronary artery bypass, or death) in group A versus group B occurred in: 1 of 30 (3%) versus 5 of 27 (18.5%) (p = 0.07) with intracoronary thrombus, 5 of 45 (9%) versus 18 of 110 (16.3%) with unstable angina, 1 of 12 (8%) versus 4 of 13 (31%) with unstable angina with intracoronary thrombus, 4 of 33 (12%) versus 14 of 97 (14.4%) with unstable angina without intracoronary thrombus, and 5 of 24 (20.8%) versus 6 of 66 (9%) with intimal dissection. Hemorrhagic complications occurred in 11% of patients who were treated with urokinase versus 9% of patients who were not (p = NS). No difference in blood transfusions existed. Thus urokinase was found to be safe during elective PTCA. In patients with intracoronary thrombus, urokinase appears to decrease the incidence of new adverse cardiac events, whereas in patients with intimal dissection it might have an adverse effect.

Prehospital thrombolysis in acute myocardial infarction

The benefit and risk of prehospital thrombolysis for acute myocardial infarction (AMI) were evaluated in a double-blind randomized trial. Patients presenting less than 4 hours after symptom onset received 2 million units of urokinase as an intravenous bolus either before (group A, n = 40) or after (group B, n = 38) hospital admission. The mean time interval from onset of symptoms to thrombolytic therapy was 85 +/- 51 minutes in group A and 137 +/- 50 minutes in group B (p less than 0.0005). In 91% of the patients, thrombolytic therapy was administered less than 3 hours after symptom onset. Complication rates during the pre- and in-hospital period were low and did not differ between groups. Three patients died (1 in group A, 2 in group B) from reinfarction 7 to 14 days after admission. Left-sided cardiac catheterization before discharge revealed a patency rate in the infarct-related artery of 61% in group A and 67% in group B (difference not significant). Global left ventricular function and regional wall motion at the infarct site did not differ significantly between group A and B (ejection fraction 51 +/- 10%, n = 28 vs 53 +/- 14%, n = 28; wall motion -2.3 +/- 1.3 vs -2.2 +/- 1.1 standard deviation, respectively). Also, peak creatine kinase did not differ significantly (838 +/- 634 U/liter in group A vs 924 +/- 595 U/liter in group B). Prehospital thrombolysis using a bolus injection of urokinase has a low risk when performed by a trained physician with a mobile care unit. The saving of 45 minutes in the early stage of an acute infarction through prehospital thrombolysis did not appear to be important for salvage of myocardial function.

Consequences of reocclusion after successful reperfusion therapy in acute myocardial infarction. TAMI Study Group

To determine the clinical consequences of reocclusion of an infarct-related artery after reperfusion therapy, we evaluated 810 patients with acute myocardial infarction. Patients were admitted into four sequential studies with similar entry criteria in which patency of the infarct-related artery was assessed by coronary arteriography 90 minutes after onset of thrombolytic therapy. Successful reperfusion was established acutely in 733 patients. Thrombolytic therapy included tissue-type plasminogen activator (t-PA) in 517, urokinase in 87, and a combination of t-PA and urokinase in 129 patients. All patients received aspirin, intravenous heparin and nitroglycerin, and diltiazem during the recovery phase. A repeat coronary arteriogram was performed in 88% of patients at a median of 7 days after the onset of symptoms. Reocclusion of the infarct-related artery occurred in 91 patients (12.4%), and 58% of these were symptomatic. Angiographic characteristics at 90 minutes after thrombolytic therapy that were associated with reocclusion compared with sustained coronary artery patency were right coronary infarct-related artery (65% versus 44%, respectively) and Thrombolysis in Myocardial Infarction (TIMI) flow 0 or 1 (21% versus 10%, respectively) before further intervention. Median (interquartile value) degree of stenosis in the infarct-related artery at 90 minutes was similar between groups: 99% for reoccluded (value, 90/100%) compared with 95% for patent (value, 80/99%). Patients with reocclusion had similar left ventricular ejection fractions compared with patients with sustained patency at follow-up. However, patients with reocclusion at follow-up had worse infarct-zone function at -2.7 (value, -3.2/-1.8) versus -2.4 (SD/chord) (value, -3.1/-1.3) (p = 0.016). The recovery of both global and infarct-zone function was impaired by reocclusion of the infarct-related artery compared with maintained patency; median delta ejection fraction was -2 compared with 1 (p = 0.006) and median delta infarct-zone wall motion was -0.10 compared with 0.34 SD/chord (p = 0.011), respectively. In addition, patients with reocclusion had more complicated hospital courses and higher in-hospital mortality rates (11.0% versus 4.5%, respectively; p = 0.01). We conclude that reocclusion of the infarct-related artery after successful reperfusion is associated with substantial morbidity and mortality rates. Reocclusion is also detrimental to the functional recovery of both global and infarct-zone regional left ventricular function. Thus, new strategies in the postinfarction period need to be developed to prevent reocclusion of the infarct-related artery.

Coronary reperfusion studies with pro-urokinase in acute myocardial infarction: evidence for synergism of low dose urokinase

Pro-urokinase is a single chain precursor of two chain urokinase, which has been shown to induce fibrin-selective plasminogen activation. In the present study, thrombolytic efficacy of 9 million U of glycosylated pro-urokinase administered intravenously was compared with that of a combined regimen utilizing 4.5 million U of pro-urokinase and 0.2 million U of urokinase. Seventy-five patients with a first myocardial infarction were randomized to receive high dose pro-urokinase (n = 40, group A) or the combination therapy (n = 35, group B). Reperfusion of the infarct-related artery was assessed by repeat coronary angiography. Thrombolysis in Myocardial Infarction trial (TIMI) grade II or III reperfusion was achieved in 73% of group A patients compared with 66% of group B patients (p = NS). A trend toward faster reopening of the infarct-related artery was observed in patients in group B. Coronary artery reocclusion occurred in 5 (10%) of 49 patients in whom angiography was repeated within 36 h after the start of therapy. Clot-selective thrombolysis was indicated by a minimal fibrinogen decline (15% and 13%, respectively, in groups A and B). Alpha 2-antiplasmin levels, however, decreased more rapidly in patients in group B (p less than 0.05). This finding and the equivalent reperfusion rate in the combined treatment group strongly suggest synergistic interaction between these two thrombolytic agents. In summary, the high incidence of reperfusion, the low rate of early reocclusion and the paucity of side effects, particularly with regard to bleeding complications, indicate that pro-urokinase possesses the characteristics of an ideal thrombolytic agent.

Future directions in plasminogen activator therapy

Thrombotic disorders such as myocardial infarction and stroke are the leading causes of death and disability in industrialized nations. Timely institution of thrombolytic therapy can achieve a reduction of infarct size, a preservation of left ventricular function, and a reduction in mortality. The administration of streptokinase, urokinase, and acylated plasminogen-streptokinase activator complex (APSAC) can be associated with a complete breakdown of the hemostatic system. Tissue-type plasminogen activator (t-PA) and single-chain urokinase-type plasminogen activator (scu-PA, prourokinase) are more fibrin specific; however, at the large dosages of activator needed for therapeutic efficacy, bleeding complications are still a problem. New approaches to optimizing the risk/benefit ratio for the patient by improving efficacy without sacrificing specificity include the use of synergistic combinations of plasminogen activators, mutants of t-PA and scu-PA, chimeric molecules, and antibody-targeted thrombolytic agents. The last approach opens the possibility of targeting several different components of the clot with either fibrinolytic or antiplatelet effector functions in one optimized molecule.