IE904654A1 - "Thrombolytically acting combined preparation" - Google Patents

Abstract

The invention concerns a preparation with thrombolytic action, consisting of a combination of the non-fibrin-binding form of the thrombolytic agent v-PA and a fibrin-binding plasminogen activator.

Description

TlIltOMnOLYTlCALLY ACTING COMBINED PREPARATION This invention relates to new agents with thrombolytic acti on .

Thromboses occur by the formation of blood clots in blood vessels. Vi!in»«.‘: thromboses including lung embolisms and arterial thromboses including acute myocardial infarctions artdistinguished . bung «mbo.ilams and myocardial infarction are lift»threatening occurrences, which require medical emergency i ntervontion.

Decides different. Invasive methods, in recent years enzymatic thrombolysis with plasminogen activators have gained acceptance us therapy form for arterial and venous thromboses. Those substances designated as thrombolytic agents convert plasminogen, the inactive proenzyme of the fibrinolysis system in tho blood into the active proteolytic enzyme plasmin. Plasmin in turn dissolves t.ho fibrous material fibrin, an essential component of a blood clot, which leads to the reopening of thi.* closed vessels and to the reconstitution of the blood flow. But plasmin is a relatively unspecific protease, i.e., once formed in the blood it destroys the proteolytic components in the blood, which are absolutely essential for an intact hemostasis (e.g. fibrinogen) and thus possibly induces danger of bleeding risks.

The first generation thrombolytic agents, streptokinase and urokinase, are subntances which, once injected into the circulation, systematically convert plasminogen into plaemin and induce a systematic proteolysis. Thrombolysis therapies with these substances are therefore often accompanied by bleeding complications. The fibrin-specific thrombolysis, developed as a result, in which the recombined plasminogen activators of the tissue type, in short called t-PA, are used, should lead out of this dilemma, t-Pa has only a slight affinity for plasminogen in the circulatory system. But in the presence of the fibrous material fibrin, with which it reacts on specific binding sites, thus affinity is increased by a multiple, which in a plasmin formation result.·; in a thrombus surface. This concept was able to be verified in vitro and in animal experimental tests; but the clinical studies showed that large amounts of t-PA are necessary, to cause the rapid dissolution of a coronary thrombosis. but if j.uch high doses of t-Pa are infused, it leads, similarly to the cases of strepokinase and urokinase, to U systematic, proteolysis connected with a relative bleeding risk. Today there is talk of a relative fibrin specificity of the t-PA. The reason for thin is an essential property of the t-PA; this molecule is a protease, which under favorable conditions (high enzyme concentration, long exposure time, high substrate concentration, optimal pH und ion medium) converts plasminogen into pliMiiuin even in the absence of fibrin. All these conditions are met. in present clinical standard therapy with t-PA.

In the search for more specific plasminogen activators, which meet the criterion of fibrin specificity, a new, natural, IE 904654 3f ibrino 1 y tj.cally netive substance with the designation v-PA (also D8PA from iJesmodus Salivary Plasminogen Activator) was found (European Patent Application, Publication No. 0 383 417).

According to the invention there is provided a thrombolytic agent comprising non-fibrin-binding forms of the thrombolytic agent v.PA (DSPA beta and DSPA gamma) with molecular weights of 46,000 and 42,000, and a fibrin-binding plasminogen activator.

The invention relates to a thrombolytically active agent consisting of tho non-tibrin-binding lower molecular forms of pypA beta and DSPA gamma with molecular weight.··; of 46,000 and 42,000 (European Patent Application, Publication No. 0 383 417) and a fibrin-binding plasminogen activator.

Suitable an i.Lbr in-bi nrii ng plasminogen activutors are e.g.: prourokinase (scu-Pa), t-Pa and the higher molecular form of the thrombolytic agent v-ΡΛ (DSPA alphal and DSPA a.lpiiu2, European Patent Application, Publication No. 0383 417) with a molecular weight of 52,000.

The thrombolytic active ingredient. v-ΡΛ (DSPA) represents a new, naturally occurring plasminogen activator which dissolves blood clots ln the human body and thus is suitable for treatment of, e.g,, myocardial infarction (European Patent Application, Publiditjon No. 0383 4.1.7), It is found in the saliva in all species of bats of the genus Desmodus spec, in small concentrations and is expressed l'roni the cells oi' the salivary glands of this animal genus. Bats of the genus Desmodus spec, comprise all. bat types of tho American continent. The genus Desmodus of Central America, and Mexico was examined especially well.

The Invention further contains pharmaceutical agents on the basis <»r the compound v-ΡΛ (DSPA) as well as the usual auxiliary agents and vehicles.

Tho fibrinolytic potency of v-PA (DSPA), in comparison with the usuul plasminogen activators, was strengthened still more by the above-deecributl combination of fibrin-binding and non-fibrinbinding plasminogen activators.

EXAMPLE Fibrinogen mid plasminogen are brought to coagulation in a Petri dish by addition of thrombin. Holes of 3 mm in diameter are punched in the resulting fibrin layer, in which now v-PA is added in different concentrations and combinations. Both molecular forms ol the fibrin-specific plasminogen activator vPA, after incubation at 37°C in a moist chamber, produce concentration dependent lysis halos.

If the two molecularly different v-PA forms are now combined with one another, lysis halos are produced which are clearly greater than the lysis halos which would be expected because of a simple additive effect. By the combination of high molecular and low molecular v-PA, a synergistic effect of the fibrinolysis is obtained in vitro. This synergistic effect is to be ascribed to the fact that the lower molecular form of v-PA, which lacks the finger domain, can be bettor diffused in a fibrin clot by ite non-fi brin-bi nding property and there unblock the blood clot by its fibrinolytic activity. The high molecular fibrin-binding Ο V-PA variant can completely lyse the already unblocked fibrin clot. calculations of the results of this fibrin platelet test have shown that by the combination of the two v-PA forms a clearly synergistic effect Is achieved (Berenbaum, M.C. Clin, exp. Immunol. 28, 1-18, 1977).

Claims (2)

1. Thrombo)ytically acting agent consisting of the combination of non-fibrin-binding forms of the thrombolytic agent v PA (DSPA beta and DSPA gamma) with molecular weights o.f 46,000 and 42,000 and fibrin-binding plasminogen activator.'·; as well as the usual auxiliary agents and Vehicles.

2. Thrombolytically acting agent according t.o claim 1, wherein the prourokinase (seu-PA), t-Pa or the high«r molecular forms of the thrombolytic agent v-PA (DSPA alphal and DSPA alpha2) with a molecular weight of 52,000 represent the fibrinbinding plasminogen activator. -6aA thrombolytic agent comprising non-fibrin-binding forms of the thrombolytic agent v.PA (DSPA beta and DSPA gamma) with molecular weights of 46,000 and 42,000 and a fibrin-binding plasminogen activator. A thrombolytic agent as claimed in claim 3 wherein the fibrin binding plasminogen activator is selected from the following: prourokinase (scu-PA), t-PA, or the higher molecular forms of the thrombolytic agent v-PA (DSPA alphal and DspA alpha2) with a molecular weight of 52,000. A thrombolytic agent as claimed in claims 3 or 4 including an auxiliary agent and\or vehicle. A thrombolytic agent substantially as hereinbefore described with reference to the Examples.