WO2001068097A1

WO2001068097A1 - Use of pyrido[3,2-e]-pyrazinones as inhibitors of phosphodiesterase 5 for treating erectile dysfunction

Info

Publication number: WO2001068097A1
Application number: PCT/EP2001/002485
Authority: WO
Inventors: Degenhard Marx; Norbert Höfgen; Ute Egerland; Stefan Szelenyi; Thomas Kronbach
Original assignee: Elbion Ag
Priority date: 2000-03-14
Filing date: 2001-03-06
Publication date: 2001-09-20
Also published as: BG107077A; HUP0300551A2; CZ20023078A3; SK13232002A3; NO20024364D0; EP1267877A1; BR0109163A; DE10012373A1; NO20024364L; IL151646A0; JP2003528056A; RU2002127413A; AR028250A1; AU2001244192A1

Abstract

The invention relates to the use of pyrido[3,2-e]-pyrazinones of formula (1) as inhibitors of phosphodiesterase 5 for treating erectile dysfunction (impotence).

Description

Use of pyrido [3,2-e] -pyrazinones as inhibitors of phosphodiesterase 5 for the therapy of ere tiler dysfunction

Technical field

This invention relates to the use of pyrido [3,2-e] -pyrazinones of the formula as active ingredients for the treatment of erectile dysfunction (impotence) and pharmaceutical preparations which contain these compounds.

State of the art

Male impotence can be defined as his inability to have sexual intercourse due to lack of erection and / or lack of ejaculation. One speaks of an erectile dysfunction, if the erection is not sufficient for the intercourse with regard to the strength or duration.

Erectile dysfunction affects approximately 10% of the male population. Men between the ages of 40 and 70 are particularly affected with about 52%. Worldwide, several million men suffer from this disease (approx. 7.5 million in Germany alone), which in most cases is organic, less often psychological. Erectile dysfunction is a common problem among older men, especially when there are other chronic conditions such as high blood pressure, atherosclerosis and diabetes. Although various active ingredients can induce an erection, they only work after an injection directly into the penis (intracavernos, ic) or instillation into the urethra (intraurethral) .This form of pharmacotherapy has been available for more than 10 years and includes the ic injection of vasoactive Substances such as papavene, phenoxybenzamine, phentolamine, moxisylyt and prostaglandin egg (PGE _T ) However, the ic use of these substances is often accompanied by serious side effects such as penis, pain or penile fibrosis However, this can cause side effects in both the man and the partner

An alternative to pharmacotherapy is surgical intervention by implanting prostheses. This form of therapy is hardly accepted by the patient due to the expected late complications (infections, circulatory disorders)

A breakthrough in the treatment of erectile dysfunction was the introduction of Sildeπafil (Viagra ^® ) by Pfizer in the USA and Europe. Sildenafil is an orally active phosphodiesterase 5 (PDE5) inhibitor, which does not directly cause an erection, but the effect of the sexual Stimulation of nitric oxide (NO) released in the penis increases NO, like its 'second messenger' cGMP, causes a vasodilation in the corpus cavemosum (swelling body) so that blood can flow in more, which causes the erection

Phosphodiesterases (PDE) are an isoenzyme family to which 10 different isoenzymes have so far been assigned. PDE enzymes cleave by hydrolysis of cyclic guanosιn-3 ^' , 5-monophosphate (cGMP) or cyclic adenosιn-3 ^' , 5 ^' -monophosphate ( cAMP), which occur as 'second messengers' in a large number of cells. Phosphodiesterase 5 (PDE 5) is cGMP-specific and dominates in the tissue of the human corpus cavernosum The inhibition of PDE 5 in the human cavernous body leads to an increase in the intracellular cGMP level induced by NO. This is associated with relaxation of the smooth muscles of the cavernous body and, as a result, an erection

Inhibitors of PDE 5 are therefore suitable as therapeutic agents for the indication of erectile dysfunction

European patent 0 400 583 relates to imidazoquinoxane of the general formula

in which A represents a nitrogen atom or CH, B and D represent a nitrogen atom or CH or a substituted carbon atom for positions 7 or 8 and the radicals R, R ^, R2 represent hydrogen or various organic substituents

DD Davey et al (J Med Chem 34 (1991), 2671-2677), in addition to various imdazo [1, 2-a] -chιnoxalιnones, also 2 imidazo [1, 5-a] -pyπdo [3,2-e] - pyrazmon of the formula

described, for which R ¹ = H and R ² = C ₂ H ₅ , as well as R ¹ = 2-methylιmιdazolo- and R = CH ₃ mean both compounds are characterized as PDE 3 inhibitors with a positive inotropic effect

Patent application WO 93/20 077 relates to imidazoquinoxahnones of the general formula

HI

O

where A stands for 5-ring heterocycles with 2 or 3 nitrogen atoms in the ring, R ^{1 can be} NO2 or CF3 and X for various nitrogen-containing ones

Chains with up to 4 chain links

These compounds are described as glutamate receptor antagonists with psychotropic as well as antnamic effects

In patent application DE 199 02 082 imidazo [1,5-a] -pyrιdo [3,2-e] - pyrazinones of the formula

described, which are inhibitors of PDE 5 For these compounds, which are each unsubstituted in 5-position, the use as therapeutic agents is Treatment of erectile dysfunction claimed According to patent application DE 199 61 302, some of these compounds are dual inhibitors of PDE 3 and PDE 5. Use of these compounds as therapeutic agents for various cardiovascular diseases is also claimed

In the patent DE 195 10 965 Pyrιdo [3,2-e] -pyrazιnone of the formula

claimed This also includes imazo [1, 5-a] -pyπdo [3,2-e] -pyrazιnone anti-asthmatic and anti-allergic properties have been described for the claimed group of substances

Description of the invention

The invention relates to Pyπdo [3,2-e] -pyrazιnone of formula 1

wherein

R, R ² , R ^{4 may be the} same or different and represent -Cι- alkyl groups, which may be straight-chain or branched-chain, and R ³ for -CH ₂ -A stands for A can

- the cyclohexyl group,

- Mono- or bicyclic aromatic hydrocarbons having 6 to 10 carbon atoms, which can be substituted one or more times with -F, -Cl, -Br, -NO ₂ , -OH, -OCH ₃ , -CH ₃ or -CN , or

- Mono- or bicyclic heteroaromatic hydrocarbons with 3 to 10

Carbon atoms and 1 to 4 heteroatoms, which are preferably N, S or O, are one or more times with -F, -Cl, -Br, -NO ₂ , -OH, -OCH ₃ , -CH ₃ or -CN can be substituted

It is an essential part of this invention that the compounds according to formula 1 have a nitrogen atom in position 9 as an essential structural prerequisite for the use according to the invention as therapeutic agents for the treatment of erectile dysfunction

The invention also relates to the physiologically acceptable salts of the compounds of the formula 1, which can be obtained by neutralizing the bases with inorganic or organic acids or by neutralizing the acids with inorganic or organic bases or by quaternizing tertiary amines to form quaternary ammonium salts Formulas are known per se from patent DE 195 10 965, to which reference has already been made in the prior art, where pyrido [3,2-e] pyrazionones were identified as dual inhibitors of PDE 4 and PDE 5, which also means that described application as anti-asthmatics or anti-allergies Those compounds of the formula Λ according to the invention in which A is a cyclohexyl group and R ¹ , R ² and R ^{4 have} the meaning described are new

The compounds of the formula according to the invention are distinguished by the fact that their inhibitory action on PDE 5 is particularly pronounced. It is the essence of this invention that the compounds according to the formula \ according to the invention are particularly suitable for use as therapeutic agents for the treatment of erectile dysfunction by this active principle are

A particular advantage of the compounds according to the invention is that they affect the cGMP level in human tissue with a high selectivity, but not the cAMP level. This has been shown for both human tissue of the heart and of the penis. With this selectivity, the risk of heart Circulatory side effects are minimized With regard to cGMP selectivity, the compounds according to the invention are superior to the standard therapeutic agent sildenafil

The compounds of the formula \ according to the invention can be administered systemically, for example intravenously, intramuscularly, subcutaneously, orally, buccally or sub ngually. Topical application, for example by inhalation or intranasally, is also possible. Oral application of 5-200 mg of the compound before Sexual intercourse is a preferred therapy regimen

Medicaments which contain one or more of the compounds of the formula according to the invention in addition to conventional physiologically acceptable carriers and / or diluents or auxiliaries, and also processes for the preparation of these medicaments are also part of this invention The compounds of formula 1 according to the invention and the medicaments which contain the compounds of formula 1 according to the invention can be used both individually and in combination with one another

It is also part of this invention that the compounds according to the invention can be used as veterinary therapeutic agents for the prophylaxis and therapy of erectile dysfunction in male mammals. The dosage, the application scheme and the galenical formulation of the compound are carried out taking into account species differences and the requirements of veterinary practice

Exemplary embodiments

The following are examples of the compounds of formula 1_ which can be used according to the invention as active ingredients for the therapy of erectile dysfunction

The compounds according to the invention are strong inhibitors of phosphodiesterase 5. Their therapeutic potential is demonstrated in vitro, for example, by increasing the effect of NO on the intracellular cGMP levels in fibroblasts in the rat, the selectivity of influencing the cAMP and cGMP levels in human tissues and the Relaxation of human corpus cavernosum demonstrated

Inhibition of phosphodiesterase 5

The PDE 5 actinate is determined in enzyme preparations from human platelets. Human blood was anticoagulated with citrate. By centrifugation at 700 xg for 20 minutes at room temperature, the platelet-rich plasma in the supernatant is separated from the erythrocytes and leukocytes. The platelets are lysed by ultrasound and in the PDE 5-assay used The phosphodiesterase activity is determined with some modifications according to the method described by Thompson et al (Thompson, WJ, Appleman, MM, Assay of cyclic nucleotide phosphodiesterase and resolution of multiple molecular forms of the enzyme Adv Cycl Nucl Res 1979, 10, 69-92) The reaction mixtures contain 50 mM Tris-HCl (pH 7.4), 5 mM MgCl2, the inhibitors in variable concentrations, the enzyme preparation and the further components necessary for the detection of the individual isoenzyme PDE 5 (see below) the addition of the substrate 0.5 μM [ ³ H] -cGMP (approx. 6000 CPM / test) is the reaction The final volume is 100 ml. Test substances are prepared as stock solutions in DMSO. The DMSO concentration in the reaction mixture is 1% v / v. At this DMSO concentration, the PDE 5 activity is not affected. After starting the reaction by adding substrate, the samples become Incubated for 30 minutes at 37 ° C. The reaction is stopped by heating the test tubes to 110 ° C for 2 minutes. The samples remain in the ice for another 10 minutes. After adding 30 μl 5 ^' - Nucleotidase (1 mg / ml, from a snake venom suspension from Crotalus adamanteus) is incubated for 10 minutes at 37 ° C. The samples are stopped on ice, 400 μl each of a mixture of Dowex-water-ethanol (1 +1 +1) are added , well mixed and incubated again on ice for 15 minutes. The reaction vessels are centrifuged for 20 minutes at 3000 xg. 200 μl aliquots of the supernatant are transferred directly into scintillation vials. After the addition of 3 ml scintillator, the samples are measured in a beta counter 100 μM IBMX determined in the determination of PDE 5 and subtracted from the test values

For the compounds of this invention were tested for the inhibition of phosphodiesterase 5 IC ₅ o - values in the range of 10 ⁹ to 10 ⁶ M determines example, were determined for selected exemplary embodiments, the following values

Induction of NO production in fibroblasts (rat)

Rat fetal lung fibroblast cells (RFL-6) are a suitable medium for examining the influence of NO on intracellular cGMP levels (Ishn et al 1991). The basic mechanism is based on the smooth vascular muscles transferable in the corpus cavernosum

The compounds according to the invention intensify the concentration-dependent increase in the intracellular cGMP levels induced by the NO donor S-nitroso-N-acetyl-D, l_-penιcιllamιn

For example, compound 13 induces a significant increase in cGMP level at a concentration of 0.10 μmol / l. The effectiveness of compound 13 is 1000 times stronger than that which is achieved by using the non-specific PDE inhibitor 3-isobutyl-1 - methylxanthιn (IBMX) reached

Influencing cAMP and cGMP levels in human tissues

The selectivity of the influence on the cGMP level compared to the cAMP level by PDE 5 inhibitors gives indications of possible side effects of the substances, especially with regard to the cardiovascular system

Strips of human atrium and human corpus cavernosum are incubated for 10 minutes with the test compounds in a concentration of 1.0 μmol / l. The preparations are frozen with liquid nitrogen and the resulting levels of the cyclic nucleotides are determined The compounds according to the invention selectively influence the cGMP level in both tissues. For example, compound 11 increases the cGMP level by 247% in human atrium tissue, while the cAMP level only increases by 1 1% in human tissue of the corpus cavernosum by compound 11 the cGMP level increased by 214%, the cAMP level only 80%

With regard to this selectivity, the compounds according to the invention are superior to the standard therapeutic agent sildenafil. Sildenafil increases the cGMP level in human atrium tissue by 147%, and the cAMP level at the same time by 240%. In human tissue of the corpus cavernosum, the cGMP is increased by sildenafil. Levels only increased by 15%, the cAMP level, however, by 238%

Relaxation of human corpus cavernosum in vitro

In an organ bath, strips of human corpus cavernosum are pre-contracted with Noradrenahn. For test compounds, the relaxing effect is determined depending on the concentration

Depending on the concentration, the compounds according to the invention have a relaxing effect on the corpus cavernosum strips pre-contracted with Noradrenahn. For example, an EC50 value of 0 15 μmol / l was determined for compound 13

Claims

claims

1. lmιdazo [1, 5-a] -pyrιdo [3,2-e] -pyrazιnone of formula 1

wherein

R ¹ , R ² , R ^{4 may be the} same or different and for

-Cι- ₄ alkyl groups, which can be straight-chain or branched-chain,

R ^{3 represents} -CH ₂ -A and

A is a cyclohexyl group

2. Use of lmιdazo [1, 5-a] -pyπdo [3,2-e] -pyrazιnones of formula 1

wherein

R ¹ , R ² , R ^{4 can be the} same or different and represent -Cι- ₄ alkyl groups, which can be straight-chain or branched-chain, and R ^{3 represents} -CH ₂ -A, where A is

- the cyclohexyl group,

mono- or bicyclic aromatic hydrocarbons having 6 to 10 carbon atoms, which can be substituted one or more times with -F, -Cl, -Br, -NO ₂ , -OH, -OCH ₃ , -CH ₃ or -CN, or

- Mono- or bicyclic heteroaromatic hydrocarbons with 3 to 10 Carbon atoms and 1 to 4 heteroatoms, which are preferably N, S or O, which one or more times with -F, -Cl, -Br, -NO ₂ , -OH, -OCH ₃ , -CH ₃ or -CN may be substituted as therapeutic agents for the manufacture of medicaments for the treatment of erectile dysfunction (impotence)

3. Use of physiologically contractual salts of the compounds of formula Λ according to claim 2, characterized by neutralization of the bases with inorganic or organic acids or by neutralizing the acids with inorganic or organic bases or by quaternization of tertiary amines to quaternary ammonium salts, as therapeutic agents for the preparation of Medicines used to treat erectile dysfunction (impotence)

4. Of the compounds of formula Λ according to claims 1 to 3 especially one of the following compounds

5-cyclohexyl-1-ethyl-8-methoxy-3-methyl-ιmιdazo [1, 5-a] -pyrιdo [3,2-e] -pyrazιnon,

5-benzyl-1-ethyl-8-methoxy-3-methyl-ιmιdazo [1, 5-a] -pyrιdo [3,2-e] -pyrazιnon,

5-benzyl-8-ethoxy-1-ethyl-3-methyl-ιmιdazo [1, 5-a] -pyπdo [3,2-e] -pyrazιnon,

5-benzyl-8-ethoxy-1,3-dimethyl-imazo [1,5-a] pyπdo [3,2-e] pyrazionone,

1-ethyl-5- (2-fluorobenzyl) -8-methoxy-3-methyl-ιmιdazo [1, 5-a] -pyrιdo [3,2-e] - pyrazinone, 5- (2-chlorobenzyl) -1-ethyl-8-methoxy-3-methyl-ιmιdazo [1, 5-a] -pyrιdo [3,2-e] - pyrazinone,

1-ethyl-8-methoxy-5- (4-methoxybenzyl) -3-methyl-ιmιdazo [1, 5-a] -pyrιdo [3,2-e] - pyrazinone,

1-ethyl-5- (4-fluorobenzyl) -8-methoxy-3-methyl-imidazo [1,5-a] -pyπdo [3,2-e] -pyrazinone,

5- (4-chlorobenzyl) -1-ethyl-8-methoxy-3-methyl-ιmιdazo [1, 5-a] -pyrιdo [3,2-e] - pyrazinone,

5- (2,6-dichlorobenzyl) -1-ethyl-8-methoxy-3-methyl-imidazo [1,5-a] -pyπdo [3,2-e] -pyrazinone,

5- (2-chloro-6-fluorobenzyl) -1-ethyl-8-methoxy-3-methyl-ιmιdazo [1, 5-a] -pyπdo [3,2-e] - pyrazinone,

5- (2,6-difluorobenzyl) -1-ethyl-8-methoxy-3-methyl-imidazo [1, 5-a] -pyπdo [3,2-e] - pyrazinone,

1-ethyl-8-methoxy-3-methyl-5- (2,3,6-trifluorobenzyl) -imidazo [1,5-a] -pyrιdo [3,2-e] -pyrazinone,

5- (2-chloro-6-fluorobenzyl) -8-methoxy-3-methyl-1-propyl-ιmιdazo [1, 5-a] -pyπdo [3,2- e] -pyrazιnon,

5- (2,6-difluorobenzyl) -8-methoxy-3-methyl-1-propyl-imidazo [1,5-a] -pyπdo [3,2-e] -pyrazinone, 8-methoxy-3-methyl-1-propyl-5- (2,3,6-tπfluorobenzyl) -ιmιdazo [1, 5-a] -pyrιdo [3,2-e] - pyrazmon,

5 - [(3,5-dimethoxoxol-4-yl) methyl] -1-ethyl-8-methoxy-3-methyl-dimazo [1,5-a] - pyπdo [3,2-e] pyrazionone,

1-ethyl-8-methoxy-3-methyl-5- (4-pyridylmethyl) -midazo [1,5-a] -pyrido [3,2-e] - pyrazmon,

1-ethyl-8-methoxy-3-methyl-5- (4-pyridylmethyl) -imidazo [1,5-a] -pyπdo [3,2-e] - pyrazmon-hydrochloride,

5 - [(2,6-Dιchlorpyπd-4-yl) methyl] -1-ethyl-8-methoxy-3-methyl-ιmιdazo [1, 5-a] - pyrιdo [3,2-e] -pyrazιnon

5. Medicament containing one or more compounds according to claims 1 to 4 in addition to conventional physiologically acceptable carriers and / or diluents or auxiliaries

6. A process for the preparation of a medicament according to claim 5, characterized in that one or more compounds according to claims 1 to 4 are processed with customary pharmaceutical carriers and / or diluents or other auxiliaries to give pharmaceutical preparations or are brought into a therapeutically usable form

7. Use of compounds of the general formula according to claims 1 to 4 and / or of pharmaceutical preparations according to claims 5 and 6 all or in combination with one another or in Combination with carriers and / or diluents or other auxiliaries.

8. Use of the compounds according to claims 1 to 4 as therapeutic agents for the manufacture of medicaments for the treatment of erectile dysfunction (impotence) according to claim 5, particularly preferably by means of oral, parenteral, buccal, intravenous, intramuscular, subcutaneous, inhalative, intranasal or sublingual application ,

9. Use of the compounds according to claims 1 to 4 as veterinary therapeutic agents for the prophylaxis and therapy of erectile dysfunction in male mammals.