JP2010531327A - Sildenafil N-oxide as a prodrug - Google Patents

Abstract

The present invention relates to sildenafil N-oxide as a prodrug, a pharmaceutical composition containing the compound, a method for producing the same, and a method for producing the composition. The present invention has the formula (1 ^A )
[Chemical 1]

1-[[3- (6,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d] pyrimidin-5-yl) -4-ethoxyphenyl represented by ] Sulfonyl] -4-methyl-4-oxide-piperazine and pharmacologically acceptable salts, hydrates and solvates thereof. Another object of the present invention is to produce a drug useful for use in the treatment of a disease or illness that can be effectively treated even if there is a side effect using sildenafil, using the compound and a composition containing the compound. It also relates to using them.
[Selection figure] None

Description

Index Page Name of the invention 1
Index 1
Technical field 1
Background art 2
Disclosure 4
Definition 6
Example 1: Analysis method 8
Example 2: Synthesis of specific compounds 11
Example 3: Pharmacological method 11
Example 4: Pharmacokinetic and pharmacological test results 12
Example 5: Pharmaceutical formulation 15
Bibliography 17
Claim 19
Summary 21

The present invention relates to the fields of pharmaceutics and organic chemistry, sildenafil N-oxides, ie formula (1 ^A ):

1-[[3- (6,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d] pyrimidin-5-yl) -4-ethoxyphenyl represented by ] Sulfonyl] -4-methyl-4-oxide-piperazine as well as pharmaceutical compositions containing this compound, methods for making the same and methods for making the compositions are also provided.

  Sildenafil is a potent selective inhibitor of cGMP-specific phosphodiesterase type 5 (PDE-V).

  In vitro tests have shown that sildenafil is selective for PDE-V. The potency it exhibits against PDE-V is higher than the potency against other known phosphodiesterases (10-fold over PDE-VI,> 80-fold over PDE-I, PDE -> 700) than for II, PDE-III, PDE-IV, PDE-VII, PDE-VIII, PDE-IX, PDE-X and PDE-XI). It is important that the selectivity to PDE-V when compared to PDE-III is about 4,000 times, because PDE-III is involved in the control of myocardial contractility. is there. When compared to the efficacy of sildenafil against PDE-VI, an enzyme present in the retina and involved in the optical signal transduction pathway of the retina, the efficacy against PDE-V is only about 10 times the efficacy against it. It is. This low selectivity is believed to be the basis for the abnormalities associated with color vision observed when doses or plasma concentrations are high.

  Sildenafil is mainly removed by liver microsomal isozymes of CYP3A4 (major pathway) and CYP2C9 (minor pathway). Such major circulating metabolites are the result of N-demethylation of sildenafil. Its metabolite (also known as UK 103,320) shows a PDE selectivity profile similar to sildenafil and its in vitro potency against PDE-V is about 50% that of the parent drug. The plasma concentration of the metabolite is about 40% of that observed with sildenafil, and as a result, the proportion of the metabolite that accounts for the pharmacological effects of sildenafil is about 20%.

It was not until 1894 that N-oxide became known. It is now very well known that N-oxide is a metabolite of various tertiary amines and also often it is an intermediate between tertiary amines and their N-dealkylated analogs. ing. Drugs that are most if not all tertiary amines produce N-oxides. This occurs, for example, in the case of morphine, imipramine, promazine, cinnarizine and nicotine. The degree to which N-oxidation occurs varies from trace amounts to almost quantitative conversion. Certain N-oxides have been shown to be more potent than their corresponding tertiary amines. The most famous example of it is chlordiazeposide ⁽ Librium®), one of the most frequently used drugs in psychiatry and general medicine. However, in more various cases, N-oxides have been found to be less potent than their corresponding tertiary amines, and most commonly N-oxidation is a metabolic inactivation. It is considered to be. N-oxide is easily reduced by chemical means in the human body to the corresponding tertiary amine, but the degree to which it occurs varies. Some N-oxides undergo almost quantitative conversion by reduction to the corresponding tertiary amine, and in other cases the conversion is merely a trace reaction or may not even occur at all (non- Patent Document 4). Thus, N-
The formation of oxides and their corresponding tertiary amines is unpredictable. When N-oxides are formed, they may be more active than the corresponding tertiary amine, less active or even completely inactive. N-oxide may or may not be reduced to the corresponding tertiary amine. When such a reaction occurs, it can be merely a trace amount or nearly quantitative.

  Since Paracelsus ('Sola dissociation factor venenum), it has been generally accepted that not only the therapeutic effects of drugs but also the toxic effects are related to their concentration at the relevant target site. Generally speaking, since it is not easy to obtain the concentration at the target site, the plasma concentration is used as an approximation of the relevant drug concentration. During drug development, it is done to limit the appropriate plasma concentration window that indicates the lower or range where efficacy appears and the upper range where side effects begin to appear. Ideally, the two concentrations are very far apart, making it easier to administer the drug in a manner that is effective and causes no side effects. In reality, things are hardly ideal, and most drugs have side effects. Often, the occurrence of side effects can be correlated with the peak plasma concentration exceeding the lower concentration associated with the occurrence of side effects.

  Side effects occur as a result of the peak plasma concentration of sildenafil. The most commonly observed side effects associated with the use of sildenafil include sneezing, headache, flushing of the face, palpitation, dyspepsia, elevated intraocular pressure, blurred vision, photophobia, severe hypotension, ventricular arrhythmia, myocardium Infarctions, strokes and persistent erectile illnesses are included. Such adverse events can severely limit the dosage, frequency and duration of drug therapy. Adverse events can be reduced by using special preparations, but such problems can also be solved by using different compounds. Thus, it would be desirable if a compound having the advantages of sildenafil could be found while avoiding such drawbacks. Prodrugs have the same pharmacological profile but exhibit a more favorable pharmacokinetic profile.

EP 0 463 756

Bickel, M.M. H. ,: “The pharmacology and Biochemistry of N-oxides”, Pharmacol. Reviews, 21 (4), 325-355, 1969

Disclosure Oral administration of sildenafil-N-oxide acting as a prodrug rapidly changes to the parent compound and N-desmethylsildenafil, an effective metabolite of sildenafil.

  The present invention also relates to pharmacologically acceptable salts, hydrates and solvates of sildenafil N-oxide, which are solvates of sildenafil and pharmacologically acceptable salts and hydrates thereof. There is a possibility that the product is not substantially contained. Sildenafil N-oxide can be prepared by subjecting sildenafil to oxidation using a suitable oxidizing agent such as m-CPBA. Pharmaceutically acceptable salts can be obtained using standard procedures well known in the art, for example by mixing a compound of the invention with a suitable acid, such as an inorganic or organic acid. Etc.

  Sildenafil N-oxide and compositions comprising them are useful for the treatment of diseases or illnesses that can be effectively treated with sildenafil even if they have side effects, namely erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH). Useful for use.

The present invention also includes:
Pharmaceutical composition for treating a disorder or disease treatable with sildenafil, comprising sildenafil N-oxide or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier object;
A method of treatment comprising administering sildenafil N-oxide or a pharmaceutically acceptable salt thereof to a mammal in need of treatment of a disorder or disease treatable by sildenafil;
A method of treatment comprising administering sildenafil N-oxide or a pharmaceutically acceptable salt thereof to a mammal in need of treatment of a disorder or disease treatable by sildenafil;
Sildenafil N for treating disorders or diseases treatable with sildenafil
A pharmaceutical composition comprising oxide or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier;
A method of treatment comprising administering sildenafil N-oxide or a pharmaceutically acceptable salt thereof to a patient in need of treatment for a disorder or disease treatable by sildenafil.

  The present invention also provides the use of sildenafil N-oxide or a salt thereof for the purpose of producing a medicament.

  The present invention further relates to combination therapy, wherein a compound of the present invention or a pharmaceutically acceptable salt thereof or a pharmaceutical composition or formulation comprising the compound of the present invention is shown in the disease For the purpose of treating one or more of these, one or more other therapeutic agents, such as sildenafil or N-desmethylsildenafil, are administered simultaneously or sequentially or as a combined preparation. Administration of one or more such other therapeutic agents can be performed before, simultaneously with, or after administration of the compound of the present invention.

  The present invention also provides compounds, pharmaceutical compositions, kits and methods for treating disorders or diseases treatable by sildenafil, wherein the method is provided to a patient in need of said treatment for sildenafil N-oxide. Or administering a pharmaceutically acceptable salt thereof.

  The present invention also provides methods for producing the compounds of the present invention and intermediates used in the methods.

  Some of the crystalline forms exhibited by the compounds may exist as polymorphs: as such are intended to belong to the present invention. In addition, some of the compounds may form solvates (ie, hydrates) with water or solvates with common organic solvents. Such solvates are also within the scope of the invention.

Sildenafil N-oxide or a pharmaceutically acceptable salt thereof that has been isotopically labeled with PET or SPECT is also within the scope of the present invention. The same has been labeled with [ ¹³ C]-, [ ¹⁴ C]-, [ ³ H]-, [ ¹⁸ F]-, [ ¹²⁵ I]-or other isotope-rich atoms. The same applies to compounds of the formula (1), which are suitable for use in receptor binding or metabolic assays.

  If sildenafil N-oxide can be found useful as a prodrug, such a compound can be used as an alternative with clinical benefits such as low peak plasma concentrations resulting in a long duration of action and a strong side effect profile. Can be used. Thus, in some embodiments of the invention, the parent compound 1- [4-ethoxy-3- (6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4 , 3-d] pyrimidin-5-yl) phenylsulfonyl] -4-methylpiperazine (sildenafil) can be provided. Substantially free, the amount of sildenafil as an impurity of the compound of the present invention is less than about 50%, 40%, 30%, 20%, 10%, 1%, 0.5%, or detection It means not contained within the limit. A pharmaceutical composition containing sildenafil N-oxide and substantially free of sildenafil is considered a composition according to the present invention.

Definitions Any compound that undergoes metabolism in vivo to become a bioactive agent (ie, sildenafil) is a prodrug within the scope and spirit of this application. Prodrugs are therapeutic agents that are essentially inactive but change to one or more effective metabolites. Prodrugs are in vivo reversible drug molecule derivatives that are used to overcome certain obstacles to the use of parent drug molecules. Such disorders include, but are not limited to, solubility, permeability, stability, metabolism and target limitations that occur before reaching the whole body (Bundgaard, 1985; King, 1994; Stella, 2004). Ettmayer, 2004; Jaervinen, 2005).

  The term 'polymorphism' defines that a compound can exist in more than one crystalline form, so-called polymorphs. Polymorphism is a phenomenon that often occurs. Polymorphs are affected by several crystallization conditions, such as temperature, degree of supersaturation, presence of impurities, solvent polarity, cooling rate, and the like. Polymorphs can be characterized in several ways, such as solid state NMR, solubility testing, DSC or melting point determination, IR or Raman spectroscopy.

  For the sake of brevity, some of the quantitative expressions given herein are not modified by the term “about”. Regardless of whether the term “about” is explicitly used, all amounts given herein are meant to refer to the actual values shown and are reasonably inferred based on ordinary skill in the art. It is understood to mean also an approximate value of the predetermined value that will be included (including an approximate value caused by the experiment and / or measurement conditions of the predetermined value). Throughout the description and claims of this specification, the word “comprising” and variations of this term, such as “comprising” and “comprising” refer to other additives, ingredients, It is not intended to exclude integers or stages. The term “composition” as used herein refers directly or indirectly by combining specified materials together with specified materials as well as products comprising the specified materials in predetermined amounts and proportions. Includes any of the resulting products. When the term relates to a pharmaceutical composition, the term includes not only a product comprising one or more active ingredients and an optional carrier (including inert materials), but any two or more Directly or indirectly by combining, combining or aggregating materials, dissociating one or more materials, or other types of reactions or interactions exhibited by one or more materials Any of the products resulting in The preparation of a pharmaceutical composition is generally carried out by associating the active ingredient uniformly and intimately with a liquid carrier or a fine solid carrier or both and then shaping the product, if necessary, to give the desired formulation. To do. The amount of active target compound contained in such pharmaceutical compositions is that which is sufficient to produce the desired effect upon the progression or condition of the disease. Accordingly, the pharmaceutical compositions of the present invention include any composition made by admixing a compound of the present invention and a pharmaceutically acceptable carrier.

  Within the context of the present application, the term 'combination formulation' includes the true combination [this is a type of formulation in which sildenafil N-oxide or a pharmaceutically acceptable salt thereof and other drugs are present, such as tablets. Or “kit-of-parts” ”[this includes sildenafil N-oxide or its pharmaceuticals] Acceptable salts and sildenafil or other drugs in separate dosage forms in addition to instructions for use, along with additional means to facilitate compliance with the administration of the optional component compounds, such as labels or figures Are included. For true combinations, drug therapy by definition is simultaneous. Administration of the contents of the 'part kit' can be performed simultaneously or at various time intervals. Whether treatment is given simultaneously or sequentially depends on the characteristics of other drugs used, characteristics such as onset and duration of action, plasma concentrations, clearance, etc. as well as the individual patient's illness, its state and characteristics Will depend on.

  “Pharmaceutically acceptable” means that the carrier, diluent or excipient must be compatible with the other materials in the formulation and not deleterious to the beneficiaries thereof.

  Dosage: The recommended therapeutic dosage is the same as that for sildenafil: 50 mg and then reduce or increase the dosage accordingly. It is also possible to change the actual dose administered to higher or lower values depending on pharmacokinetics, pharmacodynamics and other considerations. The amount of compound to be administered depends on the relevant indication, the age, weight and sex of the patient, but the physician will be able to determine the amount. The dosage will suitably be in the range of 0.01 mg / kg to 10 mg / kg. Typical daily active ingredient doses vary widely and depend on various factors such as the relevant indication, route of administration, patient age, weight and sex, etc. Could be determined. Oral and parenteral dosages will generally be in amounts ranging from 0.1 to 1,000 mg of total active ingredient per day.

  The term “therapeutically effective amount” as used herein refers to a therapeutic amount that treats or prevents a disease treatable by administering a composition of the invention. The amount is sufficient to produce a detectable therapeutic, prophylactic or ameliorative response in the tissue system, animal or human. Such effects can include, for example, the treatment and prevention of the diseases described herein. The exact amount effective for a subject depends on the size and health of the subject, the nature and extent of the disease to be treated, the recommendations of the treating physician (researcher, veterinarian, physician or other clinician) and It will depend on the therapy or combination of therapies selected for the purpose of administration. Thus, it is not effective to specify an exact effective amount in advance. The term “pharmaceutically acceptable salt” is suitable and reasonable to contact human and lower animal tissues within the scope of sound medical judgment without causing excessive toxicity, irritation, allergic reactions, etc. Refers to the salt corresponding to the benefit / risk ratio. Pharmaceutically acceptable salts are well known in the art. Their preparation can be performed in situ at the time of final isolation and purification of the compounds of the invention, or they can be pharmaceutically acceptable non-toxic bases or acids (inorganic or organic bases and inorganic or It can be prepared individually by reacting with an organic acid). The term “treatment” as used herein refers to either the treatment of a disease or condition in a mammal, preferably a human being, which includes (1) susceptible to illness but still diagnosed as ill. Preventing an unaffected subject from developing a disease or disorder, (2) suppressing or preventing the progression of the disease or disorder, (3) mitigating the disease or disorder, ie causing the regression of the disease, Or (4) to eliminate symptoms of illness. The term “pharmacotherapy” as used herein is intended to include prophylactic, diagnostic and therapeutic therapies performed in vivo or ex vivo on humans or other mammals. The term “subject” as used herein refers to an animal, preferably a mammal, most preferably a human being, subject to treatment, observation or experiment.

Analytical Method Nuclear magnetic resonance spectra ( ¹ H NMR and ¹³ C NMR, APT) were measured using a Bruker DRX 600 ( ¹ H: 600 MHz, ¹³ C: 150 MHz) at 300 K unless otherwise stated in the specified solvent. Spectral measurements were taken at Cambridge Isotop Laboratories Ltd. Performed in deuterated DMSO obtained from Chemical shift (δ) is shown in ppm downfield from tetramethylsilane ( ¹ H). The coupling constant J is indicated in Hz. The peak shape in the NMR spectrum is represented by the symbols' q '(quadruplex),' dq '(double quartet),' t '(triple line),' dt '(double triplet),' d Indicated by '(double line),' dd '(double double line),'s' (single line), 'bs' (wide single line) and' m '(multiple line). Identification of NH and OH signals was performed after mixing the sample with a drop of D ₂ O.

  Melting points were recorded using a Büchi B-545 melting point apparatus.

Flash chromatography was performed using indicator eluent and silica gel (Acros: 0.0
30-0.075 mm or Merck silica gel 60: 0.040-0.063 mm).

Reaction monitoring was performed using thin layer chromatography (TLC) on silica coated plastic sheets (pre-coated with Merck silica gel 60 F254) with the indicated eluent. Spots were visualized with ultraviolet light (254 nm) or I ₂ .

Liquid chromatography-mass spectrometry (LC-MS)
The LC-MS apparatus is configured with two Perkin Elmer series 200 micro pumps. The pumps are connected together by a 50 μl T-shaped mixing device connected to a Gilson 215 autosampler. The method is as follows:

Step Total time Flow rate (μl / min) A (%) B (%)
0 0 2000 95 5
1 1.8 2000 0 100
2 2.5 2000 0 100
3 2.7 2000 95 5
4 3.0 2000 95 5

A = 100% water (pH = + / − 3) with 0.025% HCOOH and 10 mmol NH ₄ HCOO
B = 100% ACN with 0.025% HCOOH

The autosampler is equipped with a 2 μl injection loop. The autosampler is connected to a Waters Atlantis C18 30 ^* 4.6 mm column containing 3 μm particles. The column is automatically adjusted to 40 ° C. in a Perkin Elmer series 200 column oven. The column is connected to a Perkin Elmer series 200 UV meter equipped with a 2.7 μl flow cell. Set the wavelength to 254 nm. The UV meter is connected to a Sciex API 150EX mass spectrometer. The mass spectrometer has the following parameters: Scan range: 150-900a. m. u. Polarity: positive; scan mode: profile; resolution Q1: UNIT; step size: 0.10a. m. u. Time per scan: 0.500 seconds; NEB: 10; CUR: 10; IS: 5200; TEM: 325; DF: 30; FP: 225 and EP: 10. A light scattering detector is coupled to the Sciex API 150. The light scattering detector is a Sedere Sedex 55, which operates at 50 ° C. and 3 bar N ₂ . The entire apparatus is controlled by G3 powermac.

  General biological analysis method comprising the analysis of sildenafil and its N-oxide in mouse plasma and brain samples comprising performing HPLC with MS / MS detection after protein precipitation It was performed using.

Sample preparation: Proteins in 100 μl of plasma were precipitated with acetonitrile, and a sample (5 μl) of the resulting solution was analyzed. After the whole brain was homogenized and centrifuged, a sample of the supernatant (10 μl) was analyzed.

Liquid chromato-tandem mass spectrometry (LC-MS / MS) was performed using a Sciex API 4000 LC-MS / MS. Sample quantification was performed using calibration samples extracted and processed in the same manner as the test samples so that plasma and brain samples were in the range of 1-5000 ng / ml and 5.0-5000 ng / brain, respectively. . The peak area represented by the compound was used for quantification. The calibration curve is model y = A + Bx + Cx ² (where y is the area of the peak represented by the analyte, x is the nominal calibration level (ng / ml) (plasma) or ng / g (brain), and A is the intercept) , B is the slope, and C is the curvature description). With weighing 1 / ^{x 2.} Monitoring of the performance of the LC-MS / MS instrument was performed utilizing injection of standard solutions at standard intervals. The method used was not effective in detail, so the reported concentration was a good estimate. The lower limit of quantification (LLOQ) for plasma and brain samples, respectively, was established to be 1.00 ng / ml and 5.00 ng / brain. Reverse-phase HPLC using a Hypersil BDS C18 100 × 4.6 mm 3 μm analytical column was performed at a temperature of 45 ° C. using gradient elution with a flow rate of 1.00 ml / min:

Detection using MS / MS was performed using positive MRM ionization. The following ions were measured:

Sildenafil N-oxide Sildenafil Q1 475.3 491.4
Q3 100.1 99.2

Synthesis of Specific Compounds 1-[[3- (6,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d] pyrimidin-5-yl) -4-ethoxy -Phenyl] sulfonyl] -4-methylpiperazine (sildenafil) and 1-[[3- (6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d] pyrimidine The synthesis of -5-yl) -4-ethoxy-phenyl] sulfonyl] -piperazine (N-desmethylsildenafil) was carried out as shown in EP 0 463 756.
1-[[3- (6,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d] pyrimidin-5-yl) -4-ethoxyphenyl] sulfonyl]- 4-Methyl-4-oxide-piperazine (sildenafil N-oxide):
Sildenafil free base (1.42 g, 3 mmol) was dissolved in 75 ml of dichloromethane and then cooled to -10 ° C. The mixture was mixed with meta-chloroperbenzoic acid (m-CPB
A, 0.74 g, 3 mmol, 70% in H ₂ O) was added and the solution was stirred at −10 ° C. for 2.5 hours. After adding solid K ₂ CO ₃ (2 g), the resulting mixture was stirred at 0 ° C. for an additional 30 minutes. The reaction mixture was filtered through a glass funnel and the precipitate was washed with DCM. The resulting solution was concentrated to give the title compound as a solid (1.36 g, 92%). Melting point:> 200 ° C. (decomposition). LCMS; R _t : 1.21 min, ([M + H] ⁺ = 491). ¹ H-NMR (600 MHz, D ₆ DMSO): δ 7.89-7.85 (m, 2H), 7.39 (d, J = 8 Hz, 1H), 4.18 (q, J = 7 Hz, 2H) ), 4.16 (s, 3H), 3.51-3.43 (m, 4H), 3.04 (s, 3H), 3.02-2.96 (m, 2H), 2.93- 2.88 (m, 2H), 2.78 (t, J = 7 Hz, 2H), 1.77-1.70 (m, 2H), 1.30 (t, J = 7 Hz, 3H), 0. 93 (t, J = 7 Hz, 3H).

Pharmacological methods In vitro inhibition of phosphodiesterase was performed using well-established procedures in CEREP (128, rue Danton, 92500 Rueil-Malmaison, France): PDE-I was obtained from bovine brain (Nicholson, 1989), PDE-II was obtained from human U-937 cells (Torphy, 1992), PDE-III was obtained from human platelets (Weishaar, 1986), pDE-IV was obtained from human U937 monocytes (Torphy, 1992), PDE-V Was obtained from human platelets (Weishaar, 1986) and PDE-VI was obtained from bovine retina (Ballard, 1998).

  The human large intestine model TIM2 (TNO intestinal model 2) is a dynamic model of the human large intestine that simulates the in vivo state. This is an artificial digestive system that has been proven in various studies (Minekus, 1999).

  The pharmacologically acceptable salts thereof as well as sildenafil N-oxide are prodrugs. They are useful for the treatment of diseases that can be effectively treated with sildenafil even if they have side effects, namely erectile dysfunction (impotence) and pulmonary arterial hypertension.

Pharmacokinetic and pharmacological test results Sildenafil and its N-oxide were administered individually (intravenous (iv) or oral (po)) to male NMRI mice (3 animals per hour point). ), The plasma and brain were analyzed for both compounds by LC-MS (see the method shown above). An average of the data (n = 3) was taken and they are shown in Table 1.

  When sildenafil is administered to mice (iv or po), it is only slightly metabolized to its N-oxide: its concentration in plasma is 1 of the concentration of the parent compound Never exceed -2% and no trace is measured in the brain. When sildenafil-N-oxide itself is administered, it undergoes reduction to become the parent compound. Sildenafil N-oxide i. v. About 1 hour after administration, the concentration of sildenafil in plasma and brain is higher than the concentration of N-oxide. Such effects are more pronounced after oral administration: sildenafil concentration in both plasma and brain within 10 to 100 times the concentration of N-oxide within 30 minutes of N-oxide administration Concentration.

Sildenafil-N-oxide (1 mg) was suspended in 1% methylcellulose and then inserted into the lumen (120 ml) of the TIM2 model (see above, Minekus, 1999). Samples from the lumen and dialysate (the latter is a model of the intestinal vascular bed) were taken at various time intervals and analyzed for sildenafil-N-oxide and sildenafil: Table 2:

  From the results presented above, it is clear that within 2 hours of administering sildenafil N-oxide, it has already undergone almost quantitative reduction to sildenafil. Various studies have demonstrated that TIM2 is an in vitro model that provides values that are highly predictive of gastrointestinal tract status in living humans, so that oral administration of sildenafil N-oxide also in humans Predicts that it will be reduced to sildenafil, ie it is a prodrug.

  From such data, it is clear that the two compounds show different pharmacokinetic properties. In a small pilot experiment, sildenafil and its N-oxide were individually administered to male NMRI mice (3 animals per hour) either intravenously (iv) or orally (po) After that, their plasma and brain were analyzed for the presence of N-desmethylsildenafil by LC-MS (see method shown above). Data averages (n = 3) were taken and are shown in Table 4.

  As expected, when sildenafil was administered to mice (iv or po), it was metabolized to the metabolite N-desmethyl analog, which also crosses the blood brain barrier, Because it was also present in the brain tissue. It was a novel observation that when sildenafil-N-oxide was administered, it was also observed to metabolize to N-desmethylsildenafil (which was only observed after oral administration).

  In order to investigate the activity of sildenafil-N-oxide as an inhibitor of various phosphodiesterases, the compound was also tested following sildenafil itself. The results obtained are shown in Table 5.

  The data shown in Table 5 for sildenafil confirms data known from the scientific literature, i.e. the compound is a potent inhibitor of PDE-V and PDE-VI (which is also strongly inhibited). Is highly selective for that particular subtype except for It was confirmed that the efficacy of sildenafil-N-oxide was 10 times lower than that of sildenafil itself and was found to exhibit comparable selectivity.

  In summary, oral sildenafil-N-oxide acts as a prodrug, ie it rapidly changes to the parent compound and N-desmethylsildenafil, a sildenafil metabolite reported to be about half as potent as sildenafil. . It was also confirmed that sildenafil-N-oxide itself showed almost no activity, that is, the activity it exhibited was about 1/10 that of the parent compound.

Pharmaceutical Formulations For clinical use, sildenafil N-oxide was built into a pharmaceutical composition, which is an important and novel aspect of the present invention, because they are the present compounds, It is because it contains the specific compound disclosed in this specification in more detail. The types of pharmaceutical compositions that can be used include tablets, chewable tablets, capsules (including microcapsules), solutions, parenteral solutions, ointments (creams and gels), suppositories, suspensions and Other types disclosed herein are included or will be apparent to those skilled in the art based on the present specification and general knowledge in the art. It is also possible for the active ingredient to be in the form of inclusion complexes, for example in cyclodextrins, ethers or esters thereof. Such compositions are used for oral, intravenous, subcutaneous, tracheal, bronchial, intranasal, pulmonary, transdermal, buccal, rectal, parenteral or other modes of administration. Such pharmaceutical formulations contain at least sildenafil N-oxide in admixture with at least one pharmaceutically acceptable adjuvant, diluent and / or carrier. The total amount of the active ingredient is suitably about 0.1% (w / w) to about 95% (w / w), suitably 0.5% to 50% (w / w) of the formulation, preferably Is in the range of 1% to 25% (weight / weight). In some embodiments, the amount of the active ingredient is greater than or equal to about 95% (w / w) or less than about 0.1% (w / w).

The compounds according to the invention can be mixed with auxiliary substances such as liquid or solid powdered materials such as pharmaceutically common liquid or solid fillers and extenders, solvents, emulsifiers, lubricants, flavors, colorants and / or buffers. It may be in a form suitable for administration by a usual method using a drug substance or the like. Commonly used auxiliary substances include magnesium carbonate, titanium dioxide, lactose, saccharose, sorbitol, mannitol and other sugars or sugar alcohols, talc, milk protein, gelatin, starch, amylopectin, cellulose and derivatives thereof, animal and Vegetable oils such as fish liver oil, sunflower, peanut or gum oil, polyethylene glycols and solvents such as sterile water and mono- or polyhydric alcohols such as glycerol as well as disintegrants and lubricants such as magnesium stearate, calcium stearate, Examples include sodium stearyl fumarate and polyethylene glycol wax. The mixture can then be processed into granules or compressed into tablets. Tablets are prepared using the materials shown below.

Material amount (mg / tablet)
Sildenafil N-oxide 10
Microcrystalline cellulose 200
Fumed silicon dioxide 10
Stearic acid 10
Total amount 230

  The ingredients were mixed and then compressed to give tablets each weighing 230 mg.

  The active ingredient may be individually mixed with other non-active ingredients before mixing to produce a formulation. It is also possible to produce a formulation by mixing the active ingredients with each other and then with the non-active ingredients.

  Soft gelatin capsules can be prepared by including in the capsules a mixture of the active ingredient of the present invention, vegetable oil, fat or other suitable medium for soft gelatin capsules. Hard gelatin capsules may contain granules of the active ingredient. Hard gelatin capsules can also contain a solid powder material such as lactose, saccharose, sorbitol, mannitol, potato starch, corn starch, amylopectin, cellulose derivatives or gelatin together with the active ingredient.

  Preparation of a dosage unit for rectal administration consists of (i) a suppository form in which the active substance is mixed with a neutral fat base, (ii) the active substance is vegetable oil, paraffin oil or rectal Rectal gelatin capsule form mixed with other medium suitable for gelatin capsules, (iii) ready-made fine enema form, or (iv) drying back using a suitable solvent just prior to administration It can be implemented in the form of a fine enema formulation.

Liquid preparations can be prepared in the form of syrups, elixirs, concentrated drops or suspensions, such as solutions or suspensions, in which the active ingredient is placed and the remainder such as sugar or sugar alcohol and ethanol, water , A mixture of glycerol, propylene glycol and polyethylene glycol. If necessary, such liquid preparations can contain coloring agents, flavoring agents, preservatives, saccharin and carboxymethylcellulose or other thickening agents. Liquid formulations can also be prepared in the form of a dry powder that is reconstituted with a suitable solvent prior to use. A solution for parenteral administration can be prepared as a solution containing the preparation of the present invention in a pharmaceutically acceptable solvent. Such solutions can also contain stabilizing materials, preservatives and / or buffering materials. It is also possible to prepare solutions for parenteral administration as dry formulations that are reconstituted with a suitable solvent prior to use.

  In accordance with the present invention, and a formulation comprising one or more containers filled with one or more of the materials included in the pharmaceutical composition of the present invention for use in medical treatment We also provide 'made kits'. Along with one or more such containers, various materials, such as instructions for use or instructions in the form prescribed by government agencies that regulate the manufacture, use or sale of pharmaceuticals (this notice may include humans or veterinarians). May indicate that it has been approved by a government agency to manufacture, use or sell for the purpose of pharmacological administration. Methods for use in the manufacture of a medicament and pharmaceutical treatment methods for use of the formulations of the present invention in the treatment of diseases in which inhibition of phosphodiesterase is required or required suffer from diseases in which inhibition of phosphodiesterase is required or required Administering sildenafil N-oxide in a therapeutically effective total amount to a patient who is or is susceptible to it.

  By way of example and not limitation, several pharmaceutical compositions comprising active compounds suitable for systemic use or topical application are shown. Other compounds of the invention or combinations thereof may be used in place of (and in addition to) the compounds. The concentration of the active ingredient can vary over a wide range as discussed herein. The amount and type of materials that can be included are well known in the art.

Reference List To the extent that the references listed below are useful to those skilled in the art or for the purpose of describing the invention in more detail, they are incorporated herein by reference. None of them, nor other materials cited herein, nor citations of any cited documents are admitted to be prior art materials or citations.

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Claims (12)

1-[[3- (6,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d] pyrimidin-5-yl) -4-ethoxy-phenyl] sulfonyl] -4-methyl-4-oxide-piperazine:
Pharmacologically acceptable salts, hydrates and solvates thereof.   1- [4-Ethoxy-3- (6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d] pyrimidin-5-yl) phenylsulfonyl] -4- A compound according to claim 1 which is substantially free of methyl-piperazine and its pharmacologically acceptable salts, hydrates and solvates.   A drug comprising the compound according to any one of claims 1-2 or a pharmacologically acceptable salt, hydrate or solvate thereof.   A compound according to any of claims 1-2 for the treatment of erectile dysfunction or pulmonary arterial hypertension.   In addition to a pharmaceutically acceptable carrier and / or at least one pharmaceutically acceptable auxiliary substance, at least one compound according to any one of claims 1-2 or a pharmacological thereof A pharmaceutical composition comprising a pharmaceutically acceptable salt, hydrate or solvate as an active ingredient in a pharmacologically effective amount.   (I) N-oxide of sildenafil or a pharmaceutically acceptable salt, hydrate or solvate thereof and (ii) for simultaneous, separate or sequential use in the treatment of erectile dysfunction or pulmonary arterial hypertension ) A combination pharmaceutical formulation comprising another therapeutic agent.   The combination pharmaceutical preparation according to claim 6, wherein the other therapeutic agent is sildenafil.   Use of a compound according to any of claims 1-2 for the manufacture of a pharmaceutical composition for treating erectile dysfunction or pulmonary arterial hypertension.   A method for treating erectile dysfunction or pulmonary arterial hypertension in a human or animal patient in need thereof comprising administering to said patient a therapeutically effective amount of sildenafil N-oxide. Method.   Use of the combination preparation according to claim 6 for the manufacture of a pharmaceutical composition for treating erectile dysfunction or pulmonary arterial hypertension. A method for producing sildenafil N-oxide, wherein sildenafil represented by formula (1) is oxidized with an oxidizing agent to produce sildenafil N-oxide represented by formula (1 ^A ).
Method.   The method of claim 11, wherein the oxidizing agent is m-chloroperbenzoic acid.