RU2477130C1 - Agent possessing antiarrhythmic, antifibrillatory, anti-ischemic action, and based pharmaceutical composition - Google Patents

Abstract

FIELD: medicine, pharmaceutics.

SUBSTANCE: group of inventions refers to medicine. As an agent possessing antiarrhythmic, antifibrillatory and anti-ischemic action, 1-(2-diethylaminoethyl)-2-phenylimidazo[1,2-a]benzimidazole dihydrochloride of formula

is used. A composition possessing antiarrhythmic, antifibrillatory and anti-ischemic action contains a compound of formula I taken in an effective amount as an active ingredient.

EFFECT: declared group of inventions possess high antiarrhythmic, antifibrillatory and anti-ischemic action.

2 cl, 3 dwg, 12 tbl, 1 ex

Description

The invention relates to pharmacology, in particular to biologically active substances and compositions based on them, having antiarrhythmic, anti-fibrillatory, anti-ischemic action, which can be used to create drugs for the treatment of cardiac arrhythmias of various origins, coronary circulation disorders, increase myocardial resistance to fibrillations .

Heart rhythm disturbances currently remain the main cause of cardiac deaths. Despite the progress made in the field of catheter ablation of arrhythmias and implantation of cardioverter defibrillators, it is recognized that the use of these effective invasive methods in the treatment of cardiac arrhythmias in most patients is currently impossible even without taking into account their high cost and a certain surgical risk. The effectiveness of drug therapy, estimated by restoring a stable sinus rhythm, does not exceed 50-70%.

The main strategy for the search and creation of new antiarrhythmic drugs has been and remains the principle of blockade of transmembrane ion currents in the treatment of arrhythmias, which is the basis for the classification proposed by V.Williams and modified by D. Harrison. According to this classification, 4 classes are distinguished: I - blockers of sodium channels, II - blockers of β-adrenergic receptors, III - blockers of potassium channels, IV - blockers of calcium channels.

Studies on the CAST, CASCADE and ESVEM programs have shown that despite a marked decrease in the frequency of ventricular extrasystoles, treatment with class 1 drugs not only does not reduce, but even increases the mortality due to arrhythmias, which is consistent with the data from a meta-analysis [The Cardiac Arrhythmia Suppression Trial (CAST ) investigators. Preliminary report: effect of encainide and flecainide on mortality in a randomized trial of arrhythmia supression after miocardial infarction // N. Engl. J. Med. - 1989 .-- Vol.321. - P.406-412; The Cardiac Arrhythmia Suppression Trial II Investigators. Effect of theantiarrhythmic agent moricizine on survival after myocardial infarction. N Engl J Med 1992; 327: 227-233; The CASCADE investigators. Randomized antiarrhythmic drug therapy in survivors of cardiac arrest (the CASCADE study) // Am. J. Cardiol. - 1993. - Vol. 72. - P.280-287]. In the group of patients receiving class 1 antiarrhythmics, mortality increased by 11% overall, and by selective drugs of the 1C subclass by 42% compared with the control group [N. Mazur Comparative evaluation of the effectiveness of treatment with antiarrhythmic drugs // Ter. archive. - 1994. - T.66, No. 12. - C.3-6].

Attempts to create class III antiarrhythmic drugs of a new generation - the so-called “pure” (highly selective) blockers of outgoing potassium currents (such as d-sotalol, sematilide, dofetilide, almocalant, ibutilide, risotilide, nibentan, terikalant, tedisamil, ambasilide, etc.) did not give positive results.

In studies of SWORD and SCD-HeFT, it was shown that class III antiarrhythmic drugs (d-sotalol), despite suppression of ventricular ectopic activity, worsened the prognosis of patients who had acute myocardial infarction or had severe chronic heart failure of the III-IV functional class [Yu. Belenkov N., Mareev V.Yu. Treatment of heart failure in the 21st century: achievements, questions and lessons from evidence-based medicine / Cardiology. - 2008. - No. 2. - S.6-16; Bardy G.H. et al. Amiodarone or an implantable cardioverter defibrillator for congestive heart failure. N Engl J Med 2005; 352: 3: 225-237].

In the international recommendations for the treatment of arrhythmias of the American Heart Association and the European Association of Cardiology, the most effective antiarrhythmic for the prevention of sudden cardiac death, in the treatment of atrial fibrillation and ventricular arrhythmias, cordarone is recognized [Kanorsky SG New international recommendations for the treatment of atrial fibrillation and ventricular arrhythmias: confirmation of the role of amiodarone // Clinical Pharmacology and Therapy. - 2007. - T. 16, No. 4. - S. 46-49; ACC / AHA / ESC 2006 Guidelines for the management of patients with atrial fibrillation. Eur Heart J 2006; 27: 1979-2030]. As the drug of choice, it is used by 24.1% in the USA, 34.5% - in Europe [Shubik Yu.V. Cordaron in international recommendations for the treatment of arrhythmias // Russian Medical Journal. - 2008. - T. 16, No. 21. - S.1385-1390].

Being a classical standard of class III antiarrhythmics, cordarone does not belong to pure potassium channel blockers. It has many pharmacological effects: it affects various transmembrane ionic currents - Na ⁺ , K ⁺ , Ca ⁺ ; has an adrenergic blocking effect, is a structural analogue of thyroid hormones. It is known that the effectiveness of cordarone for various rhythm disturbances is 60-90% [Gilyarov M., Sulimov V. Kordaron: past, present and future // Clinical Pharmacology and Therapy. - 2006. - T.15, No. 4. - S.60-65]. However, according to various authors, the side effects that required the abolition of cordarone were: arrhythmogenic - 0-7%, other cardiogenic and non-cardiogenic - 11.5-27% [V. Fisenko On the side effects of cordarone // Doctor. - 2003. - No. 11. - S.50-51]. So, according to a meta-analysis devoted to assessing the side effects of low doses of cordarone, the number of cases of forced discontinuation of the drug was approximately 1.5 times higher than in the placebo group [Moiseev S.V. Prevention of sudden cardiac death: a meta-analysis of randomized controlled trials // Clinical Pharmacology and Therapy. - 2009. - T.18, No. 4. - S. 52-56]. The pharmacokinetic properties (slow saturation, ability to cumulate, prolonged elimination, lack of correlation: serum concentration / likelihood of side effects) cordarone also limits its use. In addition, cordarone alters the pharmacokinetics of drugs metabolized by cytochrome P-450. It can be stated that although cordarone remains an effective antiarrhythmic in the treatment of atrial and ventricular arrhythmias, the features of pharmacokinetics and pharmacodynamics, as well as a large number of side effects seriously limit the use of this drug.

One of the new approaches to the prevention of recurrence of paroxysmal forms of atrial fibrillation and atrial flutter is treatment with combinations of antiarrhythmic drugs. Theoretically, the use of a combination of antiarrhythmics in doses reduced compared with the therapeutic is quite justified, since having different mechanisms of action and points of application, they complement each other and the spectrum of their effect on the electrophysiological mechanisms of the development of arrhythmias expands. In this case, reduced doses of the drugs that make up the combination, presumably should be easier to tolerate by patients. Combinations of half doses of ethacycin and propranolol, ethacycin and verapamil, cordarone and verapamil are recommended [Bunin Yu.A., Fedyakina L.F. Combined prophylactic antiarrhythmic therapy of atrial fibrillation and flutter // Russian Journal of Cardiology. - 2006. - No. 6 (62). - S.35-45], the use of nibentan against the background of cordarone.

In Russia, for pharmacological cardioversion of atrial fibrillation, in addition to cordarone, drugs with proven effectiveness, such as propafenone and ethacyzine, as well as insufficiently studied disopyramids, procainamide, sotalol are used [Gurevich MA Modern aspects of pharmacotherapy of atrial fibrillation // Russian Journal of Cardiology. - 2009. - No. 5 (79). - S.95-101]. Beta blockers, verapamil, diltiazem, cordaron, sotalol, propafenone, novocainamide are used for the treatment of supraventricular tachycardia [Bunin Yu.A. Pharmacotherapy of supraventricular tachycardia // Russian Journal of Cardiology. - 2009. - No. 3 (77). - S.80-88]. In accordance with the recommendations of the Ministry of Health and Social Development of Russia for primary care physicians [2007], lidocaine can be used to stop ventricular fibrillation in conditions of cardiopulmonary resuscitation.

Treatment of myocardial ischemia is aimed at improving the prognosis and preventing the occurrence of myocardial infarction or sudden death, as well as at reducing the frequency and intensity of attacks. This group of drugs includes beta-blockers, calcium antagonists, organic nitrates, antiplatelet, hypocholesterolemic agents, etc. [Diagnosis and treatment of stable angina pectoris. Recommendations of the Committee of Experts of the All-Russian Scientific Society of Cardiology, 2009]. Among them, a certain place is occupied by cordaron. It has moderate anti-ischemic properties, reducing adrenergic effects, improving coronary blood flow, normalizing myocardial contractility and oxygen delivery to the myocardium, and also has a prophylactic and therapeutic effect in case of arrhythmias caused by ischemia [National Recommendations of GFCF and OSSN for the diagnosis and treatment of heart failure (II revision) , 2010]. However, in at least 40% of cases, its administration is complicated by the dangerous side effects described earlier. In addition, the drug acts for a long time, and the subsequent use of other cardiotropic drugs, including antiarrhythmics, in patients taking amiodarone can be dangerous [Federal guidelines for the use of drugs (formulary system). Issue X. 2009].

The technical result of the invention is to increase the antiarrhythmic, anti-fibrillatory and anti-ischemic effects of drugs.

The technical result is achieved by the use of 1- (2-diethylaminoethyl) -2-phenylimidazo [1,2-a] benzimidazole dihydrochloride of the formula I:

as an agent with antiarrhythmic, antifibrillatory and anti-ischemic action.

The technical result is also achieved by a composition containing, as an active principle, 1- (2-diethylaminoethyl) -2-phenylimidazo [1,2- a ] benzimidazole dihydrochloride of formula I, taken in an effective amount.

Dihydrochloride of 1- (2-diethylaminoethyl) -2-phenylimidazo [1,2-a] benzimidazole of the formula I is known as a biologically active compound having a local anesthetic effect in infiltration, conduction and epidural anesthesia (RF patent No. 2314312, C07D 487/04, A61K 31/4188, 2008).

In the series of salts of 1- (2-diethylaminoethyl) -2-phenylimidazo [1,2- a ] benzimidazole, compounds having antiarrhythmic, antifibrillatory and anti-ischemic effects are not known.

The method for producing 1- (2-diethylaminoethyl) -2-phenylimidazo [1,2- a ] benzimidazole I dihydrochloride is described in the above patent and consists in reacting 2-phenyl-1- (2-chloroethyl) imidazo hydrochloride [1,2- a ] benzimidazole (V.A. Anisimova, A.A. Spasov, M.V. Levchenko, E. A. Aleksandrova. Chemical and pharmaceutical w., 1995, v. 29 No. 10, p. 18) with diethylamine and the subsequent translation of the obtained 1- (2-diethylaminoethyl) -2-phenylimidazo [1,2- a ] benzimidazole into a water-soluble dihydrochloride I:

Obtaining the composition consists in mixing compound I in the current dose (0.01-0.1 g) with neutral carriers and excipients approved for medical use.

As auxiliary substances can be used:

stearic acid and / or its salts as an antifriction component;

starch, polyvinylpyrrolidone, disubstituted calcium phosphate, lactose, and / or ludipress, and / or cellulose derivatives - as a filler and a binding component in the manufacture of a tablet form;

lactose and / or microcrystalline cellulose, and / or ludipress, or starch as a disintegrant to improve bioavailability.

The following is the synthesis method of the proposed compound.

Example. 1- (2-Diethylaminoethyl) -2-phenylimidazo [1,2- a ] benzimidazole dihydrochloride (I). A mixture of 3.32 g (10 mmol) of 2-phenyl-1- (2-chloroethyl) imidazo [1,2- a ] benzimidazole hydrochloride (Anisimova V.A., Spasov A.A., Levchenko M.V., Aleksandrova E .A. Chem.-Pharm. Zh., 1995, No. 10, p. 18) and 10 ml of diethylamine are heated for 5-6 hours in a sealed ampoule at 145-150 ° C. After opening the ampoule, its contents are poured into 100 ml of water and extracted with chloroform (3 × 20 ml). The extract was washed with water from an excess of diethyl amine (3 × 25 ml), dried with anhydrous Na ₂ SO ₄ , evaporated to a small volume and passed through an alumina layer, eluting with 1- (2-diethyl-aminoethyl) -2-phenylimidazo [1, 2- a ] benzimidazole chloroform. The eluate is acidified with a saturated solution of HCl in dry isopropyl alcohol, the precipitated snow-white precipitate I is filtered off after an hour, washed with dry acetone, and dried in a vacuum desiccator. Yield 75-80%. The salt is recrystallized from isopropyl alcohol (1 g / 15-16 ml) and dried at 120 ° C to constant weight. Snow-white hygroscopic needles, very easily soluble in water and ethanol with T.razl. 226-227 ° С (sealed capillary, the substance is first melted at ~ 190 ° С).

Found,%: C 55.2; H 6.7; Cl 15.5; N, 12.0.

C ₂₁ H ₂₄ N ₄ · 2HCl · 3H ₂ O.

Calculated,%: C 54.9; H 7.0; Cl 15.4; N, 12.2.

IR spectrum (petrolatum, oil), cm ^-1 : 1665 (C = N ⁺ <), 2250-2720, 3300-3600 (N ⁺ H).

¹ H NMR spectrum of the base (CDCl ₃ ), δ, ppm: 0.70 (6H, t, 2CH ₃ ), 2.35 (4H, q, N (CH ₂ ) ₂ ), 2.73 (2H t, CH ₂ N), 4.10 (2H, t, NCH ₂ ), 7.12-7.45 (10H, m, aromatic protons).

The following is an example of a tablet formulation.

The composition, wt.%:

Compound I 30.0-70.0 Stearic acid and / or its salts 1.0-1.3 lactose and / or microcrystalline cellulose and / or ludipress rest

A composition was obtained containing in wt.%: Compound I - 30.0, stearic acid - 1.0, lactose - 69.0.

Also obtained compositions containing in wt.%:

Compound I - 50.0, stearic acid - 1.2, lactose - 48.8.

Compound I - 70.0, stearic acid - 1.3, lactose - 28.7.

compound I - 30.0, the sodium salt of stearic acid - 1.0, ludipress - 69.0.

compound I - 50.0, sodium salt of stearic acid - 1.2, ludipress - 38.8.

compound I - 70.0, sodium salt of stearic acid - 1.3, ludipress - 28.7.

compound I - 30.0, the sodium salt of stearic acid - 1.0, microcrystalline cellulose - 69.0.

compound I - 50.0, sodium salt of stearic acid - 1.2, microcrystalline cellulose - 38.8.

compound I - 70.0, sodium salt of stearic acid - 1.3, microcrystalline cellulose - 28.7.

The dry components of the pharmaceutical composition are sieved, mixed, dusted with sifted dry stearic acid and / or its salts and tabletted on a rotary press with a certain diameter of punches.

The following are materials, methods and research results of compound I.

The antiarrhythmic, antifibrillatory, and anti-ischemic properties of 1- (2-diethylaminoethyl) -2-phenylimidazo [1,2- a ] benzimidazole (I) dihydrochloride were studied. Cordarone 5% solution for injection (KRKA, Slovenia) was used as a comparison drug, lidocaine was used as a 2% solution for injection (Moskhimpharmpreparaty, Russia).

All experiments were carried out in accordance with methodological guidelines and regulatory documents (GOST Z 51000.3-96 and 51000.4-96; rules and International Recommendations of the European Convention for the Protection of Vertebrate Animals Used in Experimental Research (1997); laboratory practice rules (GLP) in the Russian Federation, approved by order of the Ministry of Health of the Russian Federation of June 19, 2003 No. 267). Slaughter of animals was carried out in accordance with the requirements set forth in the "International recommendations for biomedical research using animals" (1997).

1. Antiarrhythmic properties

The effect of isolated rat atria on the myocardial refractory period was studied by the method of Ya.I. Zaydler (1967) [Zaydler Ya.I. Modeling, research methods and experimental therapy of pathological conditions. - M., 1967. - Part 3. - 46 p.]. The antiarrhythmic effect was evaluated by the assimilation by the isolated atrium of the imposed rhythm (conditional frequency threshold). The experiments were performed on isolated atria of white outbred rats of both sexes weighing 180-230 g, the minimum concentration (MEK) of the compound (M / L) was determined, which impeded the assimilation of the imposed rhythm for 15 sec.

Compound I lengthens the effective refractory period in experiments on isolated rat atria. IEC is 1.6 · 10 ⁵ M / l (table 1). The compound is 10 times higher than cordarone in terms of IEC and 2.2 times higher in therapeutic index.

Table 1 The effect of compound I and cordarone on the duration of the effective refractory period of isolated rat atria No. A drug IEC, M / L IEC, mg / kg LD ₅₀ , mg / kg Therapeutic Index (LD ₅₀ / IEC) one Compound I 1.6 · 10 ^-5 6.5 17.0 2.6 2 Cordaron 1.7 · 10 ^-4 115.9 135.5 * 1,2 * - according to Beckers (1987)

The effect of compound I on transmembrane ion currents was studied on isolated trabeculae of the atria of the frog Rana Ridibunda (diameter 150 μm, length 5-6 mm) at a temperature of 20-22 ° C. The drugs were placed in a system with a double sucrose bridge [Porotikov V.I. Study of the mechanism of action of drugs on the full permeability of myocardial membranes: Author. Dis. ... doctor. biol. sciences. - Kupavna, 1982. - 28 p.], Which made it possible to take measurements with fixing current and voltage. To study the severity of the membranotropic effect of compound I, its effect on the transmembrane ionic currents of cardiomyocytes was studied in the concentration range: 1 · 10 ^-6 , 5 · 10 ^-6 , 1 · 10 ^-5 , 5 · 10 ^-5 M. Stimulation of the drug according to the specified programs , registration of the action potential and ion currents, as well as calculation of the parameters of the action potential, excitation threshold, current-voltage characteristics, and other parameters of ion channels, the data were output in an automated mode using a SM-3 computer, coupled with an experimental setup through h modules KAMAK [Porotikov V.I., Andreeva L.A. Test report on new systemic derivatives of imidazo [1,2- a ] benzimidazole for transmembrane ionic currents. - Kupavna, 1982. - 4 p.].

As a result of the study of the effect of compound I on the transmembrane ion currents of the frog atrium trabeculae, it was found that the substance has a complex membranotropic effect (Table 2). A pronounced dose-dependent blocking effect on the outgoing potassium currents was revealed. So with the introduction of compound I at a dose of 1 · 10 ^-6 M / l, the potassium current decreased by 39%, and at a dose of 5 · 10 ^-5 M / l was blocked by 60%.

With regard to fast Na ⁺ and slow Ca ²⁺ ion currents, a dose-dependent blocking effect was not observed. So, at a dose of 5 · 10 ^{-6, the} compound inhibits the currents of sodium and calcium by 30% and 33%, respectively. With a further increase in doses, the effect on these transmembrane currents practically does not change.

Thus, a pronounced dose-dependent blocking effect on potassium currents and an insignificant inhibitory effect in large doses on sodium and calcium currents were revealed (V. Porotikov, 1982).

table 2 The effect of compound I on the transmembrane currents of trabeculae of the atria of frogs by the potential fixation method The concentration of the compound, (M / l) Ionic currents (in%) K ⁺ Na ⁺ Ca ²⁺ 1 · 10 ^-6 -39 +15 -thirty 5 · 10 ^-6 -45 -thirty -33 1 · 10 ^-5 -51 -thirty -35 5 · 10 ^-5 -60 -34 -34

The effect of compound I on the cardiac conduction system was studied using an electrocardiogram recorded in the second standard lead using the OS2-01 medical oscilloscope on the H-338-8 recorder. The experiments were performed on 20 anesthetized cats (Nembutal, 50 mg / kg, intraperitoneally). Compound I was administered intravenously at a rate of 0.15 and 0.6 mg / kg / min. The comparison drug cordarone was administered in equivalent doses intravenously at a rate of 5.0 and 20.0 mg / kg / min. The analysis of the effect of compound I and the comparison drug on electrophysiological parameters of the heart was performed at the intervals of RR, QT, QT _c , PQ.

As a result, the presence of the dependence of the effect on the dose and rate of administration was established. With continuous intravenous infusion at a rate of 0.15 mg / kg per minute, compound I for 6 minutes (total dose 0.75 mg / kg) did not statistically significantly change the RR, QT, QT _c intervals. From the 3rd minute from the start of administration, the test substance slowed the atrioventricular conductivity, which was determined by the PQ interval. At the 6th minute (in a total dose of 0.9 mg / kg), the PQ interval increased by 50% with respect to the initial data (p <0.05).

With an increase in the rate of intravenous infusion to 0.6 mg / kg per minute, compound I increased the RR interval starting from the 2nd minute of administration by 20.6% (total dose 1.2 mg / kg), and at the 4th minute (total dose 2.4 mg / kg) - by 102.9% (p <0.05), which indicates a depressing effect on the activity of the sinus node (table 3). The occurrence of bradycardia is probably due to an increase in the maximum diastolic potential due to an increase in the duration of the action potential of the sinus node. The studied compound increased myocardial refractoriness, statistically significantly changing the QT interval from the 3rd minute from the start of administration, as much as possible at the 4th minute (+ 17.4%). With an increase in the rate of administration, substance I increased the duration of the atria and atrioventricular node even more. From the 2nd minute from the start of administration (in a total dose of 1.2 mg / kg), the PQ interval lengthening was 25%, at the 3rd minute - 50% with respect to the initial data (p <0.05).

Table 3 The effect of compound I (with constant intravenous infusion at a rate of 0.6 mg / kg / min) on some indicators of the electrocardiogram (II - standard lead) of anesthetized cats (M ± n) No. Indicator initial data The time of administration of the drug (minutes) and the total dose (mg / kg) 1 (0.6) 2 (1.2) 3 (1.8) 4 (2.4) one RR, sec 0.34 ± 0.06 0.37 ± 0.05 0.41 ± 0.02 * 0.49 ± 0.04 * 0.69 ± 0.06 * 2 QT, sec 0.24 ± 0.04 0.26 ± 0.05 0.29 ± 0.08 0.34 ± 0.04 * 0.40 ± 0.05 * 3 QT _c , sec 0.41 ± 0.02 0.43 ± 0.02 0.45 ± 0.04 0.49 ± 0.03 0.48 ± 0.04 four PQ, sec 0.08 ± 0.002 0.08 ± 0.002 0.1 ± 0.008 * 0.12 ± 0.008 * 0.12 ± 0.008 * * - differences are statistically significant in relation to the initial data (p <0.05)

In relation to the QT _c interval, at the studied administration rates of 0.15 and 0.6 mg / kg per minute, a statistically significant increase was observed, which amounted to 10.5% in the last minutes (6th minute, total dose 0.9 mg / kg) and 19.5% (4th minute, total dose 2.4 mg / kg), respectively (Table 4, Fig. 1). The dynamics of the change in the QT _c interval is presented in Table 4 and Figure 1. Figure 1 shows the effect of compound I on the QT _c interval of a cat's ECG with continuous intravenous infusion, where curve 1 shows the increase in the interval when the compound is administered at a dose of 0.6 mg / kg / min, and curve 2 at a dose of 0.15 mg / kg / min.

To determine the therapeutic index, the value of ED ₁₀ was calculated - the dose in which the increase in QT _c was 10%. For compound I and cordarone, it was 0.85 and 18.3 mg / kg, respectively. The studied substance exceeds 21 times the size of ED _{10 by} 21 times, by the therapeutic index 2.7 times.

Table 4 The effect of compound I and cordarone (with constant intravenous infusion) on the change in the QT interval _{from the} electrocardiogram in the II standard lead of anesthetized cats (in delta% relative to the initial data) (M ± m) No. Substance The rate of administration, mg / kg / min The time of introduction of the substance, minutes one 2 3 four 5 6 one Water for injections 6.25 ± 2.5 6.25 ± 2.5 3.13 ± 3.13 3.13 ± 3.13 3.13 ± 3.13 9.38 ± 4.62 2 Cordaron 5,0 7.89 ± 6.23 10.52 ± 4.87 7.89 ± 2.85 5.23 ± 1.74 13.16 ± 1.47 * 23.68 ± 2.56 * 3 Cordaron 20,0 5.4 ± 3.47 13.5 ± 2.62 * 13.5 ± 2.62 * - - - four I 0.15 0.0 ± 0.0 5.26 ± 1.64 7.89 ± 2.56 7.89 ± 2.56 5.26 ± 1.64 10.53 ± 1.24 * 5 I 0.6 4.8 ± 2.62 * 9.7 ± 1.25 19.5 ± 2.35 * 17.1 ± 1.8 * - - * - differences are statistically significant in relation to the initial data (p <0.05)

Thus, a tendency towards inhibition of the function of the sinoatrial node (lengthening of the RR interval), an increase in myocardial refractoriness (lengthening of the QT _c interval), and a slowing of atrioventricular conduction (lengthening of the PQ interval), which indicates a cordaron-like effect, is shown. Changes that occur with the introduction of the studied substance depended on the dose and rate of administration.

The slowdown in the speed of sinus (lengthening the RR interval) and atrioventricular (lengthening the PQ interval) nodes is probably due to an increase in the maximum diastolic potential due to the increase in the action potential of the pacemaker cells of these nodes, as well as the blocking effect of the drug in high concentrations on sodium and calcium currents.

Compound I has a pronounced antiarrhythmic activity and is superior to the comparison drug in models of supraventricular rhythm disturbances.

Atrial rhythm disturbances were manifested by the disappearance of the P wave on the electrocardiogram and the appearance of numerous waves in its place, normal contractions disappeared on the atrial electrogram and erratic contractions of individual sections of the atria appeared. In addition, there was a decrease in blood pressure by an average of 20-40 mm Hg. The duration of rhythm disturbances averaged 58 minutes.

The effect of compound I on electrical atrial fibrillation [Samvelyan V.M., Vasilyan S.S. Antiarrhythmic properties of some anticholinergic drugs // Blood circulation. - 1981. - T. 14, No. 6. - S.13-18] was studied on 15 cats anesthetized with sodium ethaminol (50 mg / kg, intraperitoneally) weighing 2.0-4.5 kg, under conditions of mechanical ventilation, thoracotomy and transcardotomy. The following indicators were recorded: an electrocardiogram in the 2nd standard lead using an OS2-01 medical oscilloscope on an H-338-8 recorder, atrial electrogram on a KES-02 cardioencephaloscope, and blood pressure using an electrometer on an H-338-8 recorder.

Rhythm disturbances were monitored along the P wave of the electrocardiogram, changes in the atrial electrogram, and a decrease in blood pressure.

Compound I was administered intravenously (in the jugular vein) at a rate of 0.5 mg / kg per minute until sinus rhythm, atrial electrograms and normalization of blood pressure were restored. The comparison drug was administered in an equivalent volume.

The beginning of the introduction of the studied drugs in the simulation of "electrical atrial fibrillation" - 30 minutes after the occurrence of arrhythmia. The antiarrhythmic effect - restoration of the sinus rhythm lasting at least 2 minutes was taken as the minimum effective dose (MED).

As a result of the study, a pronounced antiarrhythmic effect was obtained. Compound I, with continuous intravenous infusion at a total dose of 0.91 mg / kg, restored sinus rhythm in 100% of cases and normalized the atrial electrogram. The increase in pressure occurred to the initial level. The results of a comparative analysis of antiarrhythmic activity in this arrhythmia model are presented in Table 5. Compound I exceeded cordarone both in terms of the minimum effective dose (8.5 times) and the value of the therapeutic index.

Table 5 The minimum effective dose (MED) of compound I and cordarone for arrhythmias caused by electrical atrial stimulation in cats No. Substance Number of animals MED, mg / kg LD ₅₀ , (mg / kg, w / w) Therapeutic Index, LD ₅₀ / MED one Compound I 8 0.91 ± 0.16 17.0 18.68 2 Cordaron 5 7.7 ± 0.66 135.5 * 17.59 * - according to Beckers (1987)

Compound I has pronounced antiarrhythmic activity in models of ventricular arrhythmias.

The study of the effect of compound I on ventricular arrhythmias caused by aconitine [Gendenstein E.I., Khojai Ya.I. To the pharmacology of a new antiarrhythmic drug - aymaline // Pharmacol. and toxicology. - 1961. - T.24, No. 1. - S.49-57], was performed on 28 anesthetized rats (Nembutal, 40 mg / kg, intraperitoneally) of both sexes weighing 160-240 g. Aconitine nitrate was administered intraperitoneally at a dose of 50 μg / kg. Heart rhythm disturbances were determined by electrocardiograms (2nd standard lead) with continuous visual observation on the screen of the electrocardioscope for 60 minutes. Substances were administered 5 minutes before the administration of aconitine intravenously in doses of 0.1; 0.2; 0.5; 1.0 mg / kg. The ED _{50 was} calculated - an effective dose that in 50% of cases prevents the occurrence of cardiac arrhythmias.

In an experimental model of arrhythmia caused by intravenous administration of aconitine, in control experiments, aconitine at a dose of 50 μg / kg in 100% of cases caused ventricular fibrillation and death of animals. Rhythm disturbances occurred in the first two minutes, the death of animals occurred in 20-60 minutes. ED ₅₀ - of compound I in this series of experiments turned out to be 0.3 mg / kg (Table 6). Substance I was 33.3 times more active than cordarone in terms of ED ₅₀ and 4.2 times more in therapeutic index.

Table 6 Antiarrhythmic activity of compound I and cordarone in ventricular rhythm disturbances caused by intravenous administration of aconitine in rats No. Substance Number of animals ED ₅₀ (mg / kg, w / w) LD ₅₀ , (mg / kg, w / w) Therapeutic index, LD ₅₀ / ED ₅₀ one Compound I 8 0.3 17.0 * 56.7 2 Cordaron 5 10.0 135.5 13.5 * - according to Beckers (1987)

2. Antifibrillator properties

The effect of compound I on the maximum reproducible frequency and threshold of ventricular fibrillation caused by electrical stimulation was studied on cats anesthetized with sodium ethamine (50 mg / kg, intraperitoneally) weighing 2.0-4.5 kg, under conditions of mechanical ventilation. An “ectopic focus” of excitation was created by electrical stimulation using needle electrodes sewn to the left ventricle (ES-50-01 electrostimulator) under conditions of thoracotomy and transcardotomy.

The fibrillation threshold was determined by re-scanning a vulnerable period of 90 rectangular DC pulses of 4 ms duration and increasing intensity (frequency 50 Hz) until ventricular fibrillation occurred. Defibrillation was performed using a defibrillating discharge of a given activity, created directly on the myocardium from the DI-03 defibrillator.

The threshold value was estimated as the minimum current intensity in milliamperes at which atrial or ventricular fibrillation occurred.

In the same series of experiments, the threshold of the imposed current was determined. Rectangular direct current pulses of 4 ms duration of threshold current strength (imposed rhythm threshold) and increasing frequency were fed to 1 myocardium through needle electrodes.

The threshold value was taken to be the frequency at which a breakdown of the imposed rhythm occurred and the ventricles began to contract in their rhythm. The assimilation of the imposed rhythm by the heart was determined by the ECG recorded in the second standard lead, the change in blood pressure.

Compound I was administered at doses of 1.0, 1.7, 3.0 mg / kg. The comparison drug was selected lidocaine at a dose of 5 mg / kg as one of the recommended for the relief of ventricular fibrillation [Recommendations of the Ministry of Health and Social Development of Russia for physicians providing primary health care, 2007]. All parameters were determined before and after 15, 30, 60, 90 minutes after intravenous (in the jugular vein) administration of the substance.

When stimulation of irritation in the ectopic focus exceeds the initial excitation frequency of the sinus node, single, group extrasystoles and, finally, ventricular fibrillations appear successively on the electrocardiogram.

When studying the effect of compound I on the maximum reproducible frequency and threshold of ventricular fibrillation caused by electrical stimulation, the results were obtained, which are shown in Table 7 and Fig. 2. For the occurrence of ventricular fibrillation after administration of the test compound, a significantly greater intensity of electrical irritation was required than before administration. Compound I in the dose range (1 (1/17 LD ₅₀ ); 1.7 (1/10 LD ₅₀ ) and 3 (1/6 LD ₅₀ ) mg / kg) statistically significantly increased the threshold of ventricular electrical fibrillation by 6.5; 5.4 and 20.7 times respectively. An increase in the fibrillation threshold was noted within 15-60 minutes (depending on the dose administered). The comparison drug, lidocaine, at a dose of 5 mg / kg (1/5 LD ₅₀ ) increased the threshold of electrical ventricular fibrillation by 6.9 times for 15 minutes.

Table 7 The effect of compound I and lidocaine on the threshold of electrical fibrillation of the ventricles of anesthetized cats No. Substance Dose, mg / kg, iv Initial data, mA Time (minutes) and fibrillation threshold (mA) 1 min 15 minutes 30 minutes 60 min 90 min one Compound I 1,0 2.10 ± 0.14 13.05 ± 0.94 * 5.46 ± 0.42 * 2.31 ± 0.41 2.10 ± 0.23 2.10 ± 0.23 2 1.7 4.80 ± 2.50 26.47 ± 1.85 * 22.68 ± 2.37 * 8.42 ± 1.12 * 7.24 ± 0.87 6.00 ± 1.25 3 3.0 1.90 ± 0.16 39.33 ± 4.95 * 12.54 ± 2.47 * 7.98 ± 1.5 * 2.85 ± 0.23 * 2.47 ± 0.21 four Lidocaine 5 1.90 ± 0.21 13.11 ± 1.72 * 4.94 ± 0.96 * 2.28 ± 0.10 2.34 ± 0.28 1.9 ± 0.28 * - differences are statistically significant in relation to the initial data (p <0.05)

Figure 2 shows the effect of compound I and lidocaine on the threshold of electrical fibrillation of the ventricles of anesthetized cats where curves 1-4 reflect this effect depending on the doses administered (1 - at a dose of 1 mg / kg; 2 - at a dose of 1.7 mg / kg; 3-3 mg / kg) and lidocaine (4-5 mg / kg).

A comparative analysis of the effectiveness of compound I and lidocaine relative to LD ₅₀ with intravenous administration was performed. LD _{50 of} lidocaine was taken from the literature (LD ₅₀ Rat iv 25 mg / kg [Lewis, RJ Sax's Dangerous Properties of Industrial Materials. 9th ed. Volumes 1-3. New York, NY: Van Nostrand Reinhold, 1996, p.1148] ) In a comparative analysis of the efficacy, it was found that compound I at a dose of 1 mg / kg (1/17 LD ₅₀ ) has an effect similar to lidocaine at a dose of 5 mg / kg (1/5 LD ₅₀ ) on the threshold of electrical fibrillation. In doses equivalent to 1 / 5-1 / 6 LD ₅₀ , the test compound exceeded the comparison drug both in absolute magnitude of an increase in the threshold of electrical fibrillation by 3 times and in the duration of the antifibrillator effect by 3-4 times.

Compound I at all doses statistically significantly reduced the maximum reproducible heart rate (Table 8, Fig. 3) - that is, it suppressed the ectopic pacemaker - within 30 minutes. The maximum effect of the compound was observed in the first minute at a dose of 3 mg / kg, when there was a decrease in the maximum reproducible reduction rate by 40%. Table 8 shows the effect of compound I and lidocaine on the maximum reproducible heart rate of anesthetized cats (in Δ% relative to the control).

Table 8 The effect of compound I and lidocaine on the maximum reproducible heart rate of anesthetized cats (in Δ% relative to the control) No. Substance Dose, mg / kg, iv Time (minutes) 1 min 15 minutes 30 minutes 60 min 90 min one Compound I 1,0 -23.34 ± 3.36 * -21.32 ± 9.43 * -12.00 ± 2.00 * -5.33 ± 5.33 0.00 ± 0.00 2 1.7 -28.37 ± 2.28 * -21.94 ± 2.23 * -13.25 ± 3.26 * -2.23 ± 1.33 0.00 ± 0.00 3 3.0 -40.00 ± 9.82 * -23.00 ± 9.84 * -13.96 ± 5.12 * -1.33 ± 1.33 0.00 ± 0.00 four Lidocaine 5 -36.00 ± 7.45 * -20.82 ± 6.21 * -8.00 ± 4.62 0.00 ± 0.00 0.00 ± 0.00 * - differences are statistically significant in relation to the initial data (p <0.05)

Figure 3 shows the effect of compound I and lidocaine on the maximum reproducible heart rate of anesthetized cats (in Δ% relative to the control), where curves 1-4 reflect the change in the maximum reproducible heart rate at various doses of intravenous administration of the compound (1 - in dose of 1 mg / kg; 2 - at a dose of 1.7 mg / kg; 3-3 mg / kg) and lidocaine (4-5 mg / kg).

The effect of lidocaine lasted 15 minutes, the maximum decrease in the studied parameter was in the first minute and amounted to 36%. Despite approximately the same strength of lidocaine and compound I, the effect of the second was more prolonged (2 times).

Thus, compound I exhibits pronounced antifibrillatory properties. It increases the threshold of electrical fibrillation of the ventricles of the heart to a greater extent than lidocaine, not significantly exceeding the decrease in the maximum reproducible heart rate. According to the duration of the effect, the test compound significantly exceeds the comparison drug.

3. Anti-ischemic properties

The effect of compound I on myocardial tolerance to ischemia and on the course of ischemic myocardial damage was studied on cats weighing 2.5-4.0 kg, anesthetized with nembutal (50 mg / kg, intraperitoneally), under conditions of mechanical ventilation, thoracotomy and pericardotomy. Dosed myocardial ischemia was achieved by the level of ligation (left coronary artery in its upper third) and elastic ligature. The epicardial electrocardiogram was recorded using electrodes in the form of hooks from six points on the surface of the heart: four electrodes were in the ischemic zone, two in the paraischemic zone. Recording was carried out on an EC-6T-02 electrocardiograph with thermal recording. The degree of ischemic myocardial damage was judged by the total rise of the ST segment of the epicardial electrogram [Kaverina N.V., Rozonov Yu.B., Chichkanov G.G. Modern aspects of the pharmacology of antianginal drugs. - M .: Medicine, 1980. - 240 p.].

As a comparison drug selected cordarone. The studied drugs were administered intravenously 15 minutes after occlusion of the coronary artery at a speed for compound I of 0.15 and 0.3 mg / kg / min, for cordarone - 5 and 10 mg / kg / min for 15 minutes.

In experiments to study the effect on the course of ischemic myocardial damage during occlusion of the descending branch of the left coronary artery, the studied drugs showed an anti-ischemic effect (Table 9). Compound I, administered against the background of myocardial ischemia, led to a statistically significant decrease in the total ST segment in both doses with respect to the initial level of ischemia (15 minutes after coronary occlusion). In this case, a dose-dependent effect is observed.

Table 9 The effect of compound I and cordarone on the course of experimental myocardial ischemia of anesthetized cats under conditions of controlled occlusion of the left descending branch of the coronary artery according to the dynamics of the ST segment elevation of the epicardial electrogram (in Δ% of the initial data) No. Substance The rate of introduction of the substance, mg / kg / min The time of introduction of the substance, minutes one 5 7 10 one I 0.15 -3.48 ± 1.51 -20.12 ± 2.13 * -16.89 ± 4.77 * -17.65 ± 4.43 * 2 I 0.3 -11.32 ± 6.68 -21.98 ± 5.1.5 * -40.65 ± 5.35 * -31.61 ± 13.68 3 Cordaron 5,0 -8.78 ± 5.17 -40.93 ± 7.26 * -41.58 ± 10.23 * -41.65 ± 13.75 four Cordaron 10.0 -7.28 ± 7.28 -33.41 ± 8.41 * -36.14 ± 11.14 * -37.84 ± 0.34 * * - differences are statistically significant in relation to the initial data (p <0.05)

With continuous intravenous infusion at a rate of 0.15 mg / kg, compound I maximally reduced the studied parameter (by 20.12%) at the 5th minute (total dose of 0.75 mg / kg) (p <0.05). At the same time, blood pressure did not change, the heart rate starting from 10 minutes of administration decreased by 15.4% (p> 0.05).

With continuous intravenous infusion at a rate of 0.3 mg / kg, the test substance changed the average rate of ST segment elevation for a longer time starting from the 1st minute. The maximum statistically significant decrease in the indicator (on average by 41%) occurred at the 7th minute (total dose 2.1 mg / kg). Systemic blood pressure decreased by an average of 30 mm Hg, heart rate from 10 minutes of administration decreased by 34.5% (p <0.05).

Cordarone, administered against the background of myocardial ischemia, led to a statistically significant decrease in the total ST segment in both doses with respect to the initial level of ischemia starting from the 1st minute. The maximum statistically significant decrease in the indicator (on average by 41%) occurred at the 5-7th minute.

In contrast to compound I, with the introduction of cordarone, systemic blood pressure almost immediately after the start of administration decreased by an average of 45 mm Hg, and by the end of the experiment it dropped sharply and amounted to 55 mm Hg. The heart rate decreased starting from 10 minutes of administration in 2 times (p <0.05).

A similar effect of cordarone is probably associated with fairly high doses and the rate of administration of cordarone and the manifestation of cardiotoxic properties.

To determine the therapeutic index, the value of ED ₄₀ was calculated - the dose in which the decrease in the rise in the average ST segment was 40%. For compound I and cordarone, it was 2.1 and 25.0 mg / kg, respectively (Table 10.). The studied substance surpasses cordarone in the value of ED _{40 by} 12 times, by the therapeutic index - by 1.5 times.

Thus, in experiments to study the effect on the course of ischemic myocardial damage during occlusion of the descending branch of the left coronary artery, compound I and cordaron exhibited anti-ischemic effect. Moreover, the studied compound is superior to cordarone both in absolute (ED ₄₀ ) and relative efficacy indicators (therapeutic index). In this case, the studied substance to a lesser extent than cordarone changed the systemic blood pressure.

Table 10 Anti-ischemic activity of compound I and cordarone under controlled occlusion of the left descending branch of the coronary artery in cats No. Substance ED ₄₀ (mg / kg, w / w) LD ₅₀ , (mg / kg, w / w) Therapeutic index, LD ₅₀ / ED ₅₀ one I 2.1 17.0 8.1 2 Cordaron 25.0 135.5 * 5,4 * - according to Beckers (1987)

Acute toxicity determination

To calculate the breadth of the antiarrhythmic effect of compound I, acute toxicity was determined in mice with intraperitoneal administration and in rats with intravenous administration. The calculation of the LD ₅₀ value was carried out graphically according to Miller and Teitner [Belenky M.L. Elements of a quantitative assessment of the pharmacological effect. - L., 1963. - 152 p.].

The obtained data LD _{50 of} compound I are presented in table.12.

Table 12 Acute toxicity data of compound I (LD ₅₀ ) No. Substance Animals Introduction Dose mg / kg one I Rats intravenously 17.0 Mice intraperitoneally 60.0

Statistical processing methods.

Statistical data processing was performed using the Statistica 6.0 software package. (StatSoft, USA) and Excel 2007 (MS Office XP, USA). The calculation of basic statistical indicators characterizing the variational series (arithmetic mean value M, standard error of the arithmetic mean m) was carried out. The results of the studies were evaluated using the double-tailed Student t-test with Bonferroni correction (p <0.05) and the non-parametric Mann-Whitney test.

For the test drug and the reference drug, T ₅₀ values were experimentally determined using the regression analysis method in Microsoft Excel (Office XP, Microsoft, USA).

Claims (2)

1. The use of dihydrochloride 1- (2-diethylaminoethyl) -2-phenylimidazo [1,2-a] benzimidazole of the formula I:

as a compound having antiarrhythmic, antifibrillatory and anti-ischemic action. 2. A pharmaceutical composition having antiarrhythmic, anti-fibrillatory and anti-ischemic action, characterized in that it contains 1- (2-diethylaminoethyl) -2-phenylimidazo [1,2-a] benzimidazole dihydrochloride as the active component, formula I:

taken in effective amount.

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