CA2226784C

CA2226784C - Use of cgmp-phosphodiesterase inhibitors to treat impotence

Info

Publication number: CA2226784C
Application number: CA002226784A
Authority: CA
Inventors: Alain Claude-Marie Daugan
Original assignee: Icos Corp
Current assignee: Icos Corp
Priority date: 1995-07-14
Filing date: 1996-07-11
Publication date: 2003-07-08
Anticipated expiration: 2016-07-11
Also published as: CN1195290A; US6140329A; CY2006007I2; GB9514464D0; SK284141B6; WO1997003675A1; US6608065B1; CA2226784A1; CY2006007I1; NO980153D0; ES2267111T3; PL185999B1; DE69636193D1; NO314685B1; CZ289686B6; IL122870A0; CZ3398A3; HUP9900065A2; SK284494B6; PL185737B1

Abstract

The use of compounds of formula (I) (6R, 12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':
6,1]pyrido[3,4-b]indole-1,4-dione, (3S, 6R, 12aR)-2,3,6,7,12,12a-hexahydro-2,3-dimethyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':
6,1]pyrido[3,4-b]indole-1,4-dione, and physiologically acceptable salts and solvates thereof, in the treatment of impotence.

Description

64267-892(S) USE OF C6l~lP-PHOSPHODIESTERASE INHIBITORS TO TREAT IMPOTENCE
This invention relates to the use of tetracydic derivatives which are potent and selective inhibitors of cydic guanosine 3',5'-monophosphate speciftc phosphodiesterase (cGMP specific PDE) in the treatment of impotence.
Impotence can be defined as a lack of power, in the male, to copulate and may involve an inability to achieve penile erection or ejaculation, or both.
More specifically, erectile impotence or dysfunction may be defined as an inability to obtain or sustain an erection adequate for intercourse. Its prevalence is claimed to be between 2 and 7% of the human male population, increasing with age, up to 50 years, and between 18 and 75% between 55 and 80 years of age.
1 o Reports of well-controAed clinical trials in man are few and the efficacy of orally administered drugs is low_ Although many different drugs have been shown to induce penile erection, they are only effective after direct injection into the penis, e.g. intraurethrally or intracavemosally (i.c.), and are not approved tot erectiile dysfunction. Curnent medical treatment is based on the i.c.
injection of 15 vasoactive substances and good results have been claimed with phenoxybenzamine; phentolamine, papaverine and prostaglandin E~, either alone or in combination; however, pain, priapism and fibrosis of the penis are associated with the i.c. administration of some of these agents. Potassium channel openers (KCO) and vasoactive intestinal polypeptide (VIP) have also 2 o been shown to be active i.c., but cost and stability issues could limit development of the latter. An attemative to the i.c. route is the use of glyceryl firittrate (GTN) patches applied to the penis, which has been shown to be effective but produces side-effects in both patient and partner.
As a general attemative to pharmacological intervention, a variety of penile 2 5 prostheses has been used to assist achievement of an erection. The short term success rate is good, but problems with infection and ischaemia, especially in diabetic men, make this type of treatment a ftnal option rather than first-line therapy.
The canpounds of the invention are potent inhibitors of cyclic guanosine 3',5'-3 o monophosphate phosphodiesterases (cGMP PDEs). wo 9 7 0 3 6 7 s describes the syntheses of the compounds of the invention and their utility in impotence. W095I19978. which was unpublished at the priority date of the present application, also describes the syntheses of the compounds of the invention and their utility in other diseases associated with inhibition of cGMP PDEs. The compounds may be represented bjr the following general formula (I):

N-R' R \ ~ ~ ~ Ra Rz O
and salts and solvates (e.g. hydrates) thereof, in which:
Ro represents hydrogen, halogen or C1_g alkyl;
R1 represents hydrogen, C1-6alkyl, C2~ alkenyl, C2_6 alkynyl, haloCl-6alkyl, C3_gcycloalkyl, C3_gcycloaIkyIC1_3alkyl, aryIC1_3alkyl or heteroarylCl_galkyl;
R2 represents an optionally substituted monocyclic aromatic ring selected from benzene, thiophene, furan and pyridine or an optionally substituted bicyclic i ring attached to the rest of the molecule via one of the benzene ring carbon atoms and wherein the fused ring A is a 5- or 6-membered ring which may be saturated or partially or fully unsaturated and comprises carbon atoms and optionally one or two heteroatoms selected from oxygen, sulphur and nitrogen; and R3 represents hydrogen or C~_3 alkyl, or Ri and R3 together represent a 3- or 4- membered alkyl or alkenyl chain.
Suitable individual compounds of the invention for use in the treatment of erectile dysfunction include:
Cis-2,3,6,7,12,12a-hexahydro-2-(4-pyridylmethyl)-6-(3,4-methylenedioxyphenyl)-pyrazino[2', 1' : 6,1 ]pyrido[3,4-b]indole-1,4-dione;
Cis-2,3,6,7,12,12a-hexahydro-6-(2,3-dihydrobenzo[b]furan-5-yl)-2-methyl-pyrazino[2',1':6,1 ]pyrido[3,4-b]indole -1,4-dione;
Cis-2,3,6,7,12,12a-hexahydro-6-(5-bromo-2-thienyl)-2-methyl-pyrazino[2',1':6,1 ]pyrido[3,4-b]indole -1,4-dione;

Cis-2,3,6,7,12,12an-hexahydro-2-butyl-6-(4-methylphenyl)-pyrazino[2',1':6,1 jEoyrido[3,4-b]indoie -1,4-dione;
(6R,12aR)-2,3,6,7,12,12a-Hexahydro-2-isopropyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1 ]pyrido[3,4-bjindole -1,4-dione;
(6R,12aR)-2,3,6,7,12,12a-Hexahydro-2-cyclopentyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1 ]pyrido[3,4-b]indole -1,4-dione;
(6R,12aR)-2,3,6,7,12,12a-Hexahydro-2-cyclopropylmethyl-6-(4-methoxyphenyl)-pyrazino[2',1':6,1 ]~ryrido[3,4-b)indole -1,4-dione;
(6R,12aR)-2,3,6,7,12,12a-Hexahydro-6-(3-chloro-4-methoxyphenyl)-2-methyl-pyrazino[2',1':6,1 ]~~~yrido[3,4-bjindole -1,4-dione;
(6R,12aR)-2,3,6,7,12,12a-Hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1 ]pyrido[3,4-b]indole-1,4-dione;
(6R, 12aR)-2,3,6,i',12,12a-Hexahydro-6-(3,4-methylenedioxyphenyl)-pyrazino[2', 1' : 6,11 ] pyrido [3,4-bJ indole-1,4-dione;
(SaR, 12R, 14aS)-'1,2,3,5,6,11,12,14a-Octahydro-12-(3,4-methylenedioxyph~E:nyl)-pyrrolo[1",2" : 4',5']pyrazino[2',1' : 6,1]pyrido[3,4-b]indole-5-1,4-dione;
Cis-2,3,6,7,12,12a.-hexahydro-2-cyclopropyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1 jpyrido[3,4-b]indole -1,4-dione;
(3S, 6R,12aR)-2,3,6,7,12,12a-hexahydro-3-methyl-6-(3,4-methylenedioxyph~;:nyl)-pyrazino[2',1':6,1 Jpyrido[3,4-b]indole -1,4-dione;
and physiologicall~r acceptable salts and solvates (e.g. hydrates) thereof.
The specific compr,~unds of the invention are:
(6R,12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1 ]pyrido[3,4-bJindole -1,4-dione (Compound A); and (3S, 6R, 12aR)-2,;:1,6,7,12,12a-hexahydro-2,3-dimethyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1' : 6,1]pyrido[3,4-b]indole-1,4-dione (Compound B);
and physiologicall~r acceptable salts and solvates (e.g. hydrates) thereof.
Unexpectedly, ii: has now been found that compounds of formula (I), and in particular compounds A and B, are useful in the treatment of erectile dysfunction. Furttvermore the compounds may be administered orally, thereby obviating the disadvantages associated with i.c. administration. Thus the present invention concerns the use of compounds of formula (I), and in particular compounds A and B, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing either entity, for the manufacture of a medicament for the curative or prophylactic treatment of erectile dysfunction in a male animal, including man.
The pharmaceutically acceptable salts of the compounds of formula (I), and in particular compounds A and B which contain a basic centre are acid addition salts formed with pharmaceutically acceptable acids. Examples include the hydrochloride, hydrobromide, sulphate or bisulphate, phosphate or hydrogen phosphate, acetate, benzoate, succinate, fumarate, maleate, lactate, citrate, tartrate, gfuconate, methanesulphonate, benzenesulphonate and p-toluenesulphonate salts. Compounds of formula (I), and in particular compounds A and B can also provide pharmaceutically acceptable metal salts, in particular alkali metal salts, with bases. Examples include the sodium and potassium salts.
It has been shown that compounds of the present invention are potent and selective inhibitors of cGMP specific PDE. It has now been surprisingly found that human corpus cavernosum contains three distinct PDE enzymes. The predominant PDE has further surprisingly been found to be cGMP PDE. As a consequence of the selective PDE V inhibition exhibited by compounds of the present invention, the subject compounds can elevate cGMP levels, which in turn can mediate relaxation of the corpus cavernosum tissue and consequent penile erection.
Although the compounds of the invention are envisaged primarily for the treatment of erectile dysfunction or male sexual dysfunction, they may also be useful for the treatment of female sexual dysfunction including orgasmic dysfunction related to clitoral disturbances.
Generally, in man, oral administration of the compounds of the invention is the preferred route, being the most convenient and avoiding the disadvantages associated with i.c. administration. In circumstances where the recipient suffers from a swallowing disorder or from impairment of drug absorption after oral administration, the drug may be administered parenteraily, e.g. sublingually or buccally.

For administrmtion to man in the curative or prophylactic treatment of the disorders identified above, oral dosages of a compound of formula (I), and in particular compounds A and B will generally be in the range of from 0.5-800mg daily for an average adult patient (70kg). Thus for a typical adult patient, 5 individual tablets or capsules contain from 0.2-400mg of active compound, in a suitable pharmaceutically acceptable vehicle or carrier, for administration in single or multiple doses, once or several times per day. Dosages for buccal or sublingual administration will typically be within the range of from 0.1-400 mg per single dose as required. In practice the physician will determine the actual dosing regimen ~ruhich will be most suitable for an individual patient and it will vary with the age, weight and response of the particular patient. The above dosages are exemplary of the average case but there can be individual instances in which higher or lower dosage ranges may be merited, and such are within the scope oaf this invention.
For human use;, compounds of formula (I), and in particular compounds A and B can be administered alone, but will generally be administered in admixture with a pharmaceutical carrier selected with regard to the intended route of administration and standard pharmaceutical practice. For example, the compound may toe administered orally, buccally or sublingually, in the form of tablets containing excipients such as starch or lactose, or in capsules or ovules either alone or in admixture with excipients, or in the form of elixirs or suspensions coni:,aining flavouring or colouring agents. Such liquid preparations may be prepared with pharmaceutically acceptable additives such as suspending agents (e.g. methylcellulose, a semi-synthetic glyceride such as witepsoi or mixtures of glycerides such as a mixture of apricot kernel oil and PEG-6 esters or rmixtures of PEG-8 and caprylic/capric gfycerides).
For veterinary ruse, a compound of formula (I), and in particular compound A
or B or a non-i:oxic salt thereof is administered as a suitably acceptable formulation in accordance with normal veterinary practice and the veterinary surgeon will determine the dosing regimen and route of administration which will be most appropri<~te for a particular male animal.
Thus the invention includes a pharmaceutical composition for the curative or prophylactic treatment of erectile dysfunction in a male animal, including man, comprising a compound of formula (I), and in particular compound A or B, or a pharmaceutically acceptable salt thereof, together with a pharmaceutically acceptable diluent or carrier.

64267-892(S) There is further provided a process for the preparation of a pharmaceutical _ composition for the curative or prophylactic treatment of erectile dysfunction in a male animal, including man, comprising formulating a compound of formula (I), and in particular compound A or B, or a pharmaceutically acceptable salt thereof, with a pharmaceutically acceptable diluent or carier.
The invention also provides a method of treating a male animal, including man, to cure or prevent erectile dysfunction which comprises treating said male animal with an effective amount of a compound of formula (I), and in particular compound A or B, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing either entity.
Moreover, the invention includes the use of a compound of formula (1), and in particular compound A or B, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing either entity, for the manufacture of a medicament for the curative or prophylactic treatment of erectile dysfunction in a male animal, including man.
A compound of formula (1), and in particular compound A or B, may also be used in combination with other therapeutic agents which may be useful in the treatment of erectile dysfunction substantially as hereinbefore described. The invention thus provides, in another aspect, a combination of a compound of formula (I), and in particular compound A or B together with another therapeutically active agent.
The combination referred to above may conveniently be presented for use in the fomn of a pharmaceutical formulation and thus pharmaceutical compositions comprising a combination as defined above together with a pharmaceutically acceptable diluent or carrier comprise a further aspect of the invention.
The individual components of such a combination may also be administered either sequentially or simultaneously in separate pharmaceutical formulations.
Appropriate doses of known therapeutic agents for use in combination with a compound of the invention will be readily appreciated by those skilled in the art.
One skilled in the art will readily appreciate that the compounds are generally sold in the market place in the form of a commercial package together with instructions for their use in the treatment of erectile dysfunction.

64267-892(S) 6a The compounds of the invention may be prepared by any suitable method known in the art or by the following process which forms part of the present invenfion. The process has been previously substantially described in w0 9 7 0 3 6 7 5 and in W095I19978.

Thus, a process for preparing a compound of formula (I) comprises treating a compound of forrnuia (II) O
° ~ ~OAIk R ~ I N I N~HaI
H R2 IOl ~R
(II) (in which Alk represents C1_galkyl, e.g. methyl or ethyl and Hal is a halogen atom, e.g. chlorine) with a primary amine R1 NH2 in a suitable solvent such as an alcohol (e.g. nr~ethanol or ethanol) or a mixture of solvents, conveniently at a temperature of frc~~m 20oC to reflex (e.g. at about 50oC).
A compound of formula (11) may conveniently be prepared by treating a compound of formula (III) with a compound of formula (I~
O
R° ~~ I I OAIk O Hal N NH Hal H RZ (III) (1~ R3 in a suitable solvent such as a hafogenated hydrocarbon (e.g. trichloromethane or dichioromethame), or an ether (e.g. tetrahydrofuran), preferably in the presence of a base such as an organic amine (e.g. a trialkyfamine such as triethylamine) or pan alkali metal carbonate or bicarbonate (e.g. NaHCOg). The reaction may conveniently be effected at a temperature of from -20°C to +20oC
(e.g. at about Oof.:).
A compound of formula (I) may also be prepared from a compound of formula (III) in a two-stela procedure via a compound of formula (II) isolated without purification.
Compounds of formula (I) may be prepared as individual enantiomers in two steps from the <lppropriate enantiomer of formula (III) or as mixtures (e.g.
racemates) of either pairs of cis or traps isomers from the correspondong mixtures of either pairs of cis or traps isomers of formula (III).

64267-892(S) Individual enantiomers of the compounds of the invention may be prepared from ~ racemates by resolution using methods known in the art for the separation of racemic mixtures into their constituent enantiomers, for example using HPLC
(high performance liquid chromatography) on a chiral column such as Hypersil'~
naphthylurea.
A compound of formula (III) may conveniently be prepared from a tryptophan alkyl ester of formula (~
O
Ro ~ ~ ~ ~ -OAIk w N J NH2 H M
(where Alk is as previously defined) or a salt thereof (e.g. the hydrochloride salt) with an aldehyde R2CH0. The reaction may conveniently be effected in a 1o suitable solvent such as a halogenated hydrocarbon (e.g. dichloromethane) or an aromatic hydrocarbon (e.g. toluene) in the presence of an acid such as trifluoroacetic acid. The reaction may conveniently be carried out at a temperature of from -20oC to reflux to provide a compound of formula (III) in one step. The reaction may also be carried out in a solvent such as an aromatic hydrocarbon (e.g. benzene or toluene) under reflux, optionally using a ~ean-Stark apparatus to trap the water produced.
The reaction provides a mixture of cis and traps isomers which may be either individual enantiomers or racemates of pairs of cis or traps isomers depending upon whether racemic or enantiomerically pure tryptophan alkyl ester was used 2 o as the starting material. Individual cis or traps enantiomers may conveniently be separated from mixtures thereof by fractional crystallisation or by chromatography (e.g. flash column chromatography) using appropriate solvents and eluents. Similarly, pairs of cis and traps isomers may be separated by chromatography (e.g. flash column chromatography) using appropriate eluents.
An optically pure traps isomer may also be converted to an optically pure cis isomer using suitable epimerisation procedures. One such procedure comprises treating the traps isomer or a mixture (e:g. 1 : 1 mixture) of cis and traps isomers with methanolic or aqueous hydrogen chloride at a temperature of from OoC to the refluxing temperature of the solution. The mixture may then be subjected to 3 o chromatography (e.g. flash column chromatography) to separate the resulting diastereoisomers, or in the procedure utilising aqueous hydrogen chloride the *Trade-mark 64267-892(S) ' desired cis isomer precipitates out as the hydrochloride salt which may then be isolated by filtration.
The phamnaceutically acceptable acid addition salts of a compound of formula (I), and in particular compound A or B which contain a basic centre may be prepared in a conventional manner. For example, a solution of the free base may be treated with a suitable acid, either neat or in a suitable solution, and the resulting salt isolated either by filtration or by evaporation under vacuum of the reaction solvent. Pharmaceutically acceptable base addition salts may be obtained in an analogous manner by treating a solution of compound A or B
with a suitable base. Both types of salt may be formed or interconverted using ion-exchange resin techniques.
Compounds of the invention may be isolated in association with solvent molecules by crystallisation from or evaporation of an appropriate solvent.
The syntheses of compounds A and B and of the intermediates for use therein are illustrated by the following examples.
in the Examples section hereinafter the following abbreviations are used:
MeOH (methanol) and EtOH (ethanol), 2 o t jindole-3-carboxvlate. cis isomer To a stirred solution of D-tryptophan methyl ester (11 g) and piperonal (7.9 g) in anhydrous CH2Cl2 (400 mt_) cooled at 0°C was added dropwise trifluoroacetic acid (7.7 mL) and the solution was allowed to react at ambient temperature.
After 4 days, the yellow solution was diluted with CH2CI2 (200 mL) and washed 2 s with a saturated aqueous solution of NaHC03, then with water (3x200 mL) and dried over Na2S04. The organic layer was evaporated under reduced pressure and the residue containing the two geometric isomers was purified by flash chromatography eluting with dichloromethane/ethyl acetate (97/3) to give as the firsr eluting product the title coml oa and (6.5 g) m.p. : 154°C
5 (1 R. 3R)-Methyl 1.2.3.4-tetrahydro- - 2-chlorc~rOpionyl)-1-(3.4-rrteth~rlenedioxy~n_~~-9H-pxrido(3 4-bjindole-3-carboxylate To a solution of (R)-(+)-2-chioropropionic acid (191 NI, 2.2 mmol) in anhydrous dichloromethane (30 mL), was added dicyclohexylcarbodiimide (0.45 g, 2.2. mol). Intermediate 1 (0,7 g, 2 mmol) was then added and the mixture was 10 stirred at room temperature for 20 hours. The formed precipitate of dicyclohexylurea was removed by filtration, the filtrate was evaporated in vacuo and the crude product was purified by flash chromatography eluting with toluene/ethyl acetate : 95/5. The oily compound obtained was then crystallised from ether/hexane to give the title coma oa and as pale yellow crystals (0.74 g) m.p.:126-128°C.
example 1 (78) (Compound A) 16R.12aR)-2.3.6.7.12.12a-Hexahydro-2-mett~yr~3 4-methylenedioxvahen~-py zinoj2' 1'~6, ~p~rridoj3 4-b]indole -1 4-dione a) To a stirred solution of intermediate 1 (0.5 g) and NaHC03 (0.14 g) in anhydrous CHCI3 (20 mL) was added dropwise chloroacetyl chloride (0.27 mL) at 0°C. The resulting mixture was stirred for 1 hour at the same temperature and diluted with CHCI3 (20 mL). Water (10 mL) was then added dropwise with stirring to the mixture, followed by a saturated solution of NaHC03. The organic layer was washed with water until neutrality and dried over Na2S04. After evaporation of the solvent under reduced pressure, (6R.12aR)-methyl 1 2 3,4 r r -2- I-1- 4- h I I - H- rid -b in o 3-carboxylate was obtained as an oil which was crystallised from ether to give a solid (0.38 g, m.p. : 233°C) which was used without further purification in the next step.
b) To a stirred suspension of the chloroacetyl intermediate (0.37 g) in MeOH
(20 mL) was added at room temperature a solution of methylamine (33% in EtOH) (0.4 mL) and the resulting mixture was heated at 50°C under N2 for 16 hours. The .;solvent was removed under reduced pressure and the residue was dissolved un CH2CI2 (50 mL). After washing with water (3x20 mL), drying over Na2S04 ~~nd evaporating to dryness, the residue was purified by flash chromatography eluting with CH2CI2/MeOH (99/1 ) and recrystallised from 2-propanol to give : the title com ound as white crystals (0.22 g) m.p. : 302-303°C.
Analysis for C2;2H1gN304:
Calculated:C,6'~~.86;H,4.92;N,10.79;
Found:C,67.77;H,4.92;N,10.74%.
[a]20°p = +71.0" (C=1.00; CHCI3).
(3S. 6R. 12aR, -~? 3 6 7 12 12a-hexahvdro-2 3-dimethr~6-(3 4-methylenedioxvohten~~L~yrr, azino'[2'.1' : 6.11pvridQ[3 4-b]indole-1.4-dione To a stirred solution of intermediate 2 (0.3 g, 0.68 mmol) in THF (30 mL) was added at room temperature a solution of methylamine (33 % in EtOH) (0.68 mL) and the resulting ::solution was treated at reflux under N2 for 6 days. The solvent was removed under reduced pressure and the residue was dissolved in CH2CI2 (50 mL). After mashing with water (2,25 mL), drying over Na2S04 and evaporating to dryness, the crude product was purified by flash chromatography eluting with dichloromethane/methanol : 9911. The oily residue obtained was crystallised from rnethanol to give the title compound as white crystals (40 mg) m.p. : 307-309°C.
Analysis for C23H;a~N3O4 Calculated : C, 68.47 ; H, 5.25 ; N, 10.42 ;
Found : C, 68.35; H, 5.33; N, 10.42%.
[a]2o°p = + 65.2° (~;: = 1.15 ; CHCI3).

The following compound was similarly prepared:
Exam'Lhe 33 (3S. 6R" 12aR)-2.3.6.7.1 ~,12a-Hexahydro-~-met x~(3 4-meth~rlenedioxvphenyy-cwrazino(2' 1''6 'I-).p~rrid2[~~.4 b~indole 1 4-dione as white crystals using ammonia as the base.
m.p. : 319-321 °C.
Analysis for C22H19N304 Calculated : C, 67.86 ; H, 4.92 ; N, 10.79 ;
Found : C, 67.86; H, 5.17; N, 10.72%.
(oc]20"p = + 107° (c = 1 ; pyridine).
Compounds A and B have been included in pharmacy formulations and details of such formulations are given below.
TABLETS FOR ORAL ADMINISTRATION
A. Direct Compression 1. mgltablet Active ingredient 50.0 Crospovidone USNF g.0 Magnesium Stearate Ph Eur 1.0 Anhydrous Lactose 141.0 The active ingredient was sieved and blended with the excipients. The resultant mix was compressed into tablets.

2. mgltablet Actives ingredient 50.0 Colloi~cial Silicon Dioxide 0.5 Crosp~~ovidone 8.0 Sodium Lauryl Sulphate 1.0 Magn~E~sium Stearate Ph Eur 1.0 Microc:rystal(ine Cellulose USNF 139.5 The active ingredient was sieved and blended with the excipients. The resultant mix was compressed into tablets.
B. WET GRANULATION
1. mgltablet Active ingredient 50.0 Polyvinyl pyrollidone 150.0 Polyethylene glycol 50.0 Polysiarbate 80 10.0 MagmEaium Stearate Ph Eur 2.5 Crosc:armellose Sodium 25.0 Colloi~,ial Silicon Dioxide 2.5 Micro~:;rystalline Cellulose USNF 210.0 The polyvinyl pyrollidone, polyethylene glycol and polysorbate 80 were dissolved in water. The resultant solution was used to granulate the active ingredient. After drying the granules were screened, then extruded at elevated temperatures and pressures. The extrudate was milled and/or screened then was blended with the microcrystalline cellulose, croscarmellose sodium, colloidal silicon dioxide and magnesium stearate.
The resultant mix was compressed into tablets.
2. mgltablet Active ingredient 50.0 Polysorbate 80 3.0 Lactose Ph Eur 178.0 Starch BP 45.0 Pregelatinised Maize Starch BP 22.5 Magnesium Stearate BP 1.5 The active ingredient was sieved and blended with the lactose, starch and pregelatinised maize starch. The polysorbate 80 was dissolved in purified water. Suitable volumes of the polysorbate 80 solution were added and the powders were granulated. After drying, the granules were screened and blended with the magnesium stearate. The granules were then compressed into tablets.
Tablets of other strengths may be prepared by altering the ratio of active ingredient to the other excipients.
FILM COATED TABLETS
The aforementioned tablet formulations were film coated.
Coating Suspension ~ % wow 64267-892(S) Opadry whitet ~ 13.2 Purified water Ph Eur ~ to 100.0*
* The water did not appear in the final product. The maximum theoretical weight of solids applied during coating was 20mgltablet.
t Opadry'~white is a proprietary material obtainable from Colorcon Limited, UK
which contains hydroxypropyl methylceAulose, titanium dioxide and triacetin.
5 The tablets were film coated using the coating suspension in conventional film coating equipment.
CAPSULES
mglcapsule Active ingredient 50.0 Lactose 148.5 Polyvinyl pyrollidone 7 00.0 Magnesium Stearate 1.5 *Trade-mark 64267-892(S) The active ingredient was sieved and blended with the excipients_ The mix was filed into size No. 1 hard gelatin capsules using suitable equipment.
mglcapsule Active ingredient 50.0 Microcrystatline Cellulose 233.5 Sodium t-auryi Sutphate 3_0 Crospovidone 12.0 Magnesium Stearate 1.5 The active ingredient was sieved and blended with the excipients. The mix was filled into size No. 1 hard gelatin capsules using suitable equipment.
Other doses may be prepared by altering the ratio of active ingredient to excipient, the fill weight and if necessary changing the capsule size.
3, mglcapsule Active ingredient 50.0 Labrafil M1944CS to 1.0 ml The active ingredient was sieved and blended with the Labrafil* The suspension was filled into soft gelatin capsules using appropriate equipment.
Inhibitory effect on cGMP-POE
l0 cGMP-PDE activity of compounds of the present invention was measured using a one-step assay adapted from Wells at al. (Wells, J. N., Baird, C. E., Wu, Y_ J.
and Hardman, J. G., Biochim_ Biophys. Acta 384, 430 (1975)). The reaction *Trade-mark 64267-892(S) 16a medium contained 50mM Tris-HCI,pH 7.5, 5mM Mg-acetate, 250pglml 5'-Nucleotidase, 1rnM EGTA and 0.15pM 8-[H3]-cGMP. The enzyme used was a human recombinant PDE V (ICOS, Seattle USA).
Compounds of the invention were dissolved in DMSO finally present at 2% in the assay. The incubation time was 30 minutes dung which the total substrate conversion did not exceed 30%.
The ICso values for the compounds examined were determined from concentration-response curves using typically concentrations ranging from 10nM
to 10~M. Tests against other PDE enzymes using standard methodology also ' showed that compounds of the invention are highly selective for the cGMP
specific PDE en;ayme.
J
-~GMP level me,5jsurements Rat aortic smooith muscle cells (RSMC) prepared according to Chamiey et al. in Cell Tissue Res. 177, 503 - 522 (1977) were used between the 10th and 25th passage at coni~uence in 24-well culture dishes. Culture media was aspirated and replaced ~ivith PBS (0.5m1) containing the compound tested at the appropriate concentration. After 30 minutes at 37°C, particulates guanylate cyclase was stinoulated by addition of ANF (100nM) for 10 minutes. At the end of incubation, the medium was withdrawn and two extractions were pertormed by addition of 6:5% ethanol (0.25m1). The two ethanolic extracts were pooled and evaporated until dryness, using a Speed-vac system. c-GMP was measured afte;:r acetylation by scintillation proximity immunoassay (AMERSHAM).
The compound; according to the present invention were typically found to exhibit an ICSO value of less than 500nM, and an ECSO value of less than 5. In vitro test data for' representative compounds of the invention is given in following Table 1:
Table 1 ExampIe.No. ICS° nM ECS° ~,M
1 2 0.2 2 2 0.2 The above data demonstrates the ability of the subject compounds of the invention to inhil:>it cGMP PDE, and hence their utility in the treatment of erectile dysfunction sub:~,tantially as hereinbefore described.

Claims

CLAIMS:

1. A pharmaceutical composition for the curative or prophylactic treatment of erectile dysfunction in a male animal, comprising a compound of formula (I):
or a physiologically acceptable salt or solvate thereof, wherein:
R0 represents hydrogen, halogen or C1-C6alkyl;
R1 represents hydrogen, C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, haloC1-C6alkyl, C3-C8cycloalkyl, C3-C8cycloalkylC1-C3alkyl, arylC1-C3alkyl or heteroarylC1-C3alkyl;
R2 represents an optionally substituted monocyclic aromatic ring selected from the group consisting of benzene, thiophene, furan and pyridine, or an optionally substituted bicyclic ring attached to the rest of the molecule via one of the benzene ring carbon atoms, wherein the fused ring A is a 5- or 6-membered ring which may be saturated or partially or fully unsaturated and comprises carbon atoms and optionally one or two heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; and R3 represents hydrogen or C1-C3alkyl, or R1 and R3 together represent a 3- or 4-membered alkyl or alkenyl chain, together with a pharmaceutically acceptable diluent or carrier.

2. A pharmaceutical composition for the curative or prophylactic treatment of erectile dysfunction in a male animal, comprising a compound selected from the group consisting of:
(6R,12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione or a physiologically acceptable salt or solvate thereof; and (35,6R,12aR)-2,3,6,7,12,12a-hexahydro-2,3-dimethyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione or a physiologically acceptable salt or solvate thereof, together with a pharmaceutically acceptable diluent or carrier.

3. The composition according to claim 1 or 2, wherein the solvate is a hydrate.

4. The composition according to any one of claims 1 to 3, wherein the animal is human.

5. A commercial package comprising a compound of formula (I):
or a physiologically acceptable salt or solvate thereof, wherein R0 represents hydrogen, halogen or C1-C6alkyl;
R1 represents hydrogen, C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl , haloC1-C6alkyl , C3-C8cycloalkyl, C3-C8cycloalkylC1-C3alkyl, arylC1-C3alkyl or heteroarylC1-C3alkyl;
R2 represents an optionally substituted monocyclic aromatic ring selected from the group consisting of benzene, thiophene, furan and pyridine, or an optionally substituted bicyclic ring attached to the rest of the molecule via one of the benzene ring carbon atoms, wherein the fused ring A is a 5- or 6-membered ring which may be saturated or partially or fully unsaturated and comprises carbon atoms and optionally one or two heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; and R3 represents hydrogen or C1-C3alkyl, or R1 and R3 together represent a 3- or 4-membered alkyl or alkenyl chain, together with instructions for its use in combination with another therapeutically active agent useful in the treatment of erectile dysfunction, in the treatment of erectile dysfunction in a male animal.

6. The commercial package according to claim 5, wherein said solvate is a hydrate.

20a

7. The commercial package according to claim 5 or 6, wherein said animal is human.

8. A pharmaceutical formulation comprising a combination as defined in any one of claims 5 to 7 together with a pharmaceutically acceptable diluent or carrier.

9. Use of a compound of formula (I):
or a physiologically acceptable salt or solvate thereof, wherein:
R0 represents hydrogen, halogen or C1-C6alkyl;
R1 represents hydrogen, C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, haloC1-C6alkyl, C3-C8cycloalkyl, C3-C8cycloalkylC1-C3alkyl, arylC1-C3alkyl or heteroarylC1-C3alkyl;

R2 represents an optionally substituted monocyclic aromatic ring selected from the group consisting of benzene, thiophene, furan and pyridine, or an optionally substituted bicyclic ring attached to the rest of the molecule via one of the benzene ring carbon atoms, wherein the fused ring A is a 5- or 6-membered ring which may be saturated or partially or fully unsaturated and comprises carbon atoms and optionally one or two heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; and R3 represents hydrogen or C1-C3alkyl, or R1 and R3 together represent a 3- or 4-membered alkyl or alkenyl chain, for manufacturing a medicament for the curative or prophylactic treatment of erectile dysfunction in a male animal.

10. Use of a compound selected from the group consisting of:
(6R,12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione or a physiologically acceptable salt or solvate thereof; and (3S,6R,12aR)-2,3,6,7,12,12a-hexahydro-2,3-dimethyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione or a physiologically acceptable salt or solvate thereof, for manufacturing a medicament for the curative or prophylactic treatment of erectile dysfunction in a male animal.

11. Use of a compound of formula (I):
or a physiologically acceptable salt or solvate thereof, wherein:
R0 represents hydrogen, halogen or C1-C6alkyl;
R1 represents hydrogen, C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, haloC1-C6alkyl, C3-C8cycloalkyl, C3-C8cycloalkylC1-C3alkyl, arylC1-C3alkyl or heteroarylC1-C3alkyl;
R2 represents an optionally substituted monocyclic aromatic ring selected from the group consisting of benzene, thiophene, furan and pyridine, or an optionally substituted bicyclic ring attached to the rest of the molecule via one of the benzene ring carbon atoms, wherein the fused ring A is a 5- or 6-membered ring which may be saturated or partially or fully unsaturated and comprises carbon atoms and optionally one or two heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; and R3 represents hydrogen or C1-C3alkyl, or R1 and R3 together represent a 3- or 4-membered alkyl or alkenyl chain, for the curative or prophylactic treatment of erectile dysfunction in a male animal.

12. Use of a compound selected from the group consisting of:
(6R,12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione or a physiologically acceptable salt or solvate thereof; and (3S,6R,12aR)-2,3,6,7,12,12a-hexahydro-2,3-dimethyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione or a physiologically acceptable salt or solvate thereof, for the curative or prophylactic treatment of erectile dysfunction in a male animal.

13. Use according to any one of claims 9 to 12, wherein the solvate is a hydrate.

14. Use according to any one of claims 9 to 13, wherein the animal is human.

15. Use of a composition according to any one of claims 1 to 4 for the curative or prophylactic treatment of erectile dysfunction in a male animal.

16. Use of a combination according to any one of claims 5 to 7 for the curative or prophylactic treatment of erectile dysfunction in a male animal.

17. Use of a formulation according to claim 8 for the curative or prophylactic treatment of erectile dysfunction in a male animal.

18. Use according to any one of claims 9 to 17, wherein the compound, medicament, composition, combination or formulation is used or is adapted to be used orally.

19. A commercial package comprising a compound of formula (I):

or a physiologically acceptable salt or solvate thereof, wherein:

R0 represents hydrogen, halogen or C1-C6alkyl;

R1 represents hydrogen, C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, haloC1-C6alkyl, C3-C8cycloalkyl, C3-C8cycloalkylC1-C3alkyl, arylC1-C3alkyl or heteroarylC1-C3alkyl;

R2 represents an optionally substituted monocyclic aromatic ring selected from the group consisting of benzene, thiophene, furan and pyridine, or an optionally substituted bicyclic ring attached to the rest of the molecule via one of the benzene ring carbon atoms, wherein the fused ring A is a 5- or 6-membered ring which may be saturated or partially or fully unsaturated and comprises carbon atoms and optionally one or two heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; and R3 represents hydrogen or C1-C3alkyl, or R1 and R3 together represent a 3- or 4-membered alkyl or alkenyl chain, together with instructions for its use in the treatment of erectile dysfunction in a male animal.

20. A commercial package comprising a compound selected from the group consisting of:

(6R,12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione or a physiologically acceptable salt or solvate thereof; and (3S,6R,12aR)-2,3,6,7,12,12a-hexahydro-2,3-dimethyl-6-(3,4-methylenedioxyphenyl)-pyrazino[2',1':6,1]pyrido[3,4-b]indole-1,4-dione or a physiologically acceptable salt or solvate thereof, together with instructions for its use in the treatment of erectile dysfunction in a male animal.

21. The commercial package according to claim 19 or 20, wherein the solvate is a hydrate.

22. The commercial package according to any one of claims 19 to 21, wherein the animal is human.

23. A process for preparing a pharmaceutical composition according to any one of claims 1 to 4, comprising formulating the compound, or a physiologically acceptable salt or solvate thereof, with a pharmaceutically acceptable diluent or carrier.

24. Use of a compound of formula (I):

or a physiologically acceptable salt or solvate thereof, wherein:

R0 represents hydrogen, halogen or C1-C6alkyl;

R1 represents hydrogen, C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, haloC1-C6alkyl, C3-C8cycloalkyl, C3-C8cycloalkylC1-C3alkyl, arylC1-C3alkyl or heteroarylC1-C3alkyl;

R2 represents an optionally substituted monocyclic aromatic ring selected from the group consisting of benzene, thiophene, furan and pyridine, or an optionally substituted bicyclic ring attached to the rest of the molecule via one of the benzene ring carbon atoms, wherein the fused ring A is a 5- or 6-membered ring which may be saturated or partially or fully unsaturated and comprises carbon atoms and optionally one or two heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; and R3 represents hydrogen or C1-C3alkyl, or R1 and R3 together represent a 3- or 4-membered alkyl or alkenyl chain, for manufacturing a medicament for the curative or prophylactic treatment of female sexual dysfunction.

25. Use of a compound of formula (I):

or a physiologically acceptable salt or solvate thereof, wherein:

R0 represents hydrogen, halogen or C1-C6alkyl;

R1 represents hydrogen, C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, haloC1-C6alkyl, C3-C8cycloalkyl, C3-C8cycloalkylC1-C3alkyl, arylC1-C3alkyl or heteroarylC1-C3alkyl;

R2 represents an optionally substituted monocyclic aromatic ring selected from the group consisting of benzene, thiophene, furan and pyridine, or an optionally substituted bicyclic ring attached to the rest of the molecule via one of the benzene ring carbon atoms, wherein the fused ring A is a 5- or 6-membered ring which may be saturated or partially or fully unsaturated and comprises carbon atoms and optionally one or two heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; and R3 represents hydrogen or C1-C3alkyl, or R1 and R3 together represent a 3- or 4-membered alkyl or alkenyl chain, for the curative or prophylactic treatment of female sexual dysfunction.

26. Use according to claim 24 or 25, wherein the solvate is a hydrate.

27. Use according to any one of claims 24 to 26, wherein the sexual dysfunction is an orgasmic dysfunction.

28. Use according to any one of claims 24 to 27, wherein the compound or medicament is used or is adapted to be used orally.