AU2014200451B2 - Use of amidoxime carboxylic acid esters and n-hydroxyguanidine carboxylic acid esters for producing prodrugs - Google Patents

Abstract

The invention relates to a method for improving bioavailability of pharmaceutical substances and for allowing said pharmaceutical substances to permeate the blood brain barrier, said pharmaceutical substances having at least one or more amidine, guanidine, N-hydroxyamidine (amidoxime) or N-hydroxyguanidine-functions. The invention also relates to medicaments containing correspondingly modified pharmaceutical substances.

Description

PCT/EP2009/051132 USE OF AMIDOXIME CARBOXYLIC ACID ESTERS AND N-HYDROXYGUANIDINE CARBOXYLIC ACID ESTERS FOR PRODUCING PRODRUGS 5 The present invention relates to a use of an amidoxime carboxylic acid ester in a method for improving the bioavailability and enabling the blood-brain barrier crossing of medicinal substances, which have at least one or more amidine functions, guanidine functions, N hydroxyamidine (amidoxime) functions or N-hydroxyguanidine functions, and drugs containing correspondingly modified medicinal substances. 10 N-hydroxyamidines (amidoximes) and N-hydroxyguanidines represent known prodrug principles for increasing the oral bioavailability of amidines [Clement, B. Methoden zur Behandlung und Prophylaxe der Pneumocystis carinii Pneumonie (PCP) und anderen Erkrankungen sowie Verbindungen und Formulierungen zum Gebrauch bei besagten 15 Methoden, P 432444.4, 1993] and guanidines. Pharmaceutical preparations containing an active agent having one or more amidine or guanidine functions exhibit almost no pharmacological effect in oral application. The precondition for a therapeutical effect of an active agent after oral administration is represented 20 by its resorption from the gastrointestinal tract. The most important mechanism of such an effect is passive diffusion. The degree of resorption by way of passive diffusion is dependent on the lipophilicity and thus also the acidity and basicity of the active agent. Highly basic compounds such as amidines and guanidines are present in the stomach (pH 1) 25 and small intestine (pH 6.4) in an almost completely protonated form. A resorption after oral administration, which requires the passing of lipid bilayers of the membranes of the gastrointestinal tract, therefore only occurs to a very low degree. Another problem in the medication of many diseases is the necessity to cross the blood-brain 30 barrier. The blood-brain barrier is an effective barrier with regard to the resorption of substances into the brain. It ensures the selective uptake and prevents the penetration of substances. Furthermore, the blood-brain barrier does no only act as a physical but also as an enzymatic barrier. Various processes are involved in the penetration of substances into the brain. As compared to other indications, only few drugs are marketed, which develop their 35 effect in the central nervous system (CNS). The greater part thereof reaches the CNS by PCT/EP2009/051132 -2 diffusion. Diseases like epilepsy, chronic pain or depressions are treated this way. Other serious functional disorders such as brain tumors or amyotrophic lateral sclerosis yet cannot be treated in this way today [PARDRIDGE, W. M. NeuroRx 2005, 2, 3-14]. For being able to cross the blood-brain barrier by way of passive diffusion, a substance is required to be lipophilic, have a 5 lower molecular weight than 400 - 500 Da, and be present in an uncharged state. For resorbing specifically small molecules such as glucose or amino acids, various transporter systems such as nucleoside transporters, influx and efflux transporters for organic anions, glucose transporters, peptide transporters, and amino acid transporters are expressed on the blood-brain barrier [TAMAI, I.; TSUJI, A. J. Pharm Sci 2000, 89, 1371-1388 and DE BOER, A.; VAN 10 DER SANDT, I. Annu Rev Pharmacol Toxicol 2003, 43, 629-656]. Larger molecules such as insulin or iron-containing transferrin are resorbed via the receptor-mediated transport. In this case, the insulin and transferrin receptors particularly play an important role [DE BOER, A.; VAN DER SANDT, I. Annu Rev Phamacol Toxicol 2003, 43, 629-656; PARDRIDGE, W. M. Mol Interv 2003, 3, 90-105]. Taking the amino acid L-dopa as an example, one has used a 15 prodrug principle for the water-soluble catecholamine dopamine to be capable of passing the blood-brain barrier. The transport is performed by the amino acid transporter LAT1 (large neutral amino acid transporter). After the passage, the decarboxylation into dopamine takes place [PARDRIDGE, W. M. Mol Interv 2003, 3, 90-105]. 20 Diamidines are used as antiparasitic agents against malaria, pneumocystis jiroveci (previously carinii) pneumonia, trypanosomiasis (African sleeping sickness), and leishmaniasis [WERBOVETZ, K. Curr Opin Investig Drugs 2006, 7, 147-157]. Particularly in developing countries, these diseases represent a serious problem involving high mortality rates. 25 Three diamidines to be applied parenterally are on the market. Pentamidine (Pentacarinat*) has been used in the early stage of the African sleeping sickness already for 60 years. Efficiency is no longer provided in the 2 stage of the African sleeping sickness, the meningo-encephalitic stage, since the blood-brain barrier cannot be passed successfully. As a result, highly toxic arsenic compounds must be administered. There is a lack of medicinal substances which are 30 efficient in the 2 stage of the African sleeping sickness.

PCT/EP2009/051132 -3 It is likely that all of the active agents, which have an amidine or a guanidine as a functional group, exhibit an insufficient resorption in the oral application, if they can only be resorbed by passive diffusion. 5 Medicinal substances containing carboxylic acids are very widely used and can also be applied as oral dosage forms. In particular, analgesics from the group of acetic acid, propionic acid and salicylic acid derivatives must be mentioned here. The N-hydroxylated derivatives such as amidoximes, and the N-hydroxyguanidines, due to the 10 introduction of the oxygen atom, exhibit a lower basicity. Under physiological conditions, they are not present in a protonated form. Benzamidoxime represents a model compound for many medicinal substances containing an amidoxime function [Clement, B., Drug Met Rev 2002, 34, 565-579]. 15 Pentamidine and diminazene represent diamidines and are not resorbed after oral application. They were therefore transferred into amidoxime prodrugs. (DE 10 2006 034 256.9). The example pentamidine demonstrates that the transfer into the pentoxime ester also entails a reduction of the solubility. This probably is also the reason for the bioavailability of 20 pentamidine not to reach one hundred percent after oral application of the pentoxime ester [Clement, B.; B Urenheide, A.; Rieckert, W.; Schwarz, J., ChemMedChem 2006, 1, 1260-7]. Furthermore, the reduced water solubility induces the disadvantage that an administration of the medicinal substance is no longer possible by injecting aqueous solutions. This is a problem, 25 particularly when an oral administration is out of question. It is therefore the task of the present invention to increase the water solubility and thus also the oral bioavailability of substances, which had been transferred into amidoxime prodrugs or N hydroxyguanidine prodrugs, and/or thus to enable the passing of the blood-brain barrier. 30 The task is solved by the use according to the invention having the features of claim 1. The subclaims indicate advantageous arrangements of the invention.

PCT/EP2009/051132 -4 Description of the invention According to the invention, amidoxime carboxylic acid esters (I) and the N-hydroxyguanidine carboxylic acid esters (II) of the following formulas are proposed to be used: (1) (I ) 0

OR

1 O

OR

1 N N'

NH

2 N NH 2 H 2 5 wherein n = 0 - 12, and R 1 represents hydrogen, an alkyl or aryl radical, or the salts thereof as a substitute for one or more amidine functions, N-hydroxyamidine (amidoxime) functions, guanidine functions or N-hydroxyguanidine functions of a medicinal substance in drugs for improving the solubility, bioavailability and enabling the medicinal substance to pass the blood 10 brain barrier. If n is selected to be greater than 12, an improvement of the solubility, bioavailability and capacity of the medicinal drug to pass the blood-brain barrier is no longer given. 15 N-hydroxyamidines (amidoximes) and N-hydroxyguanidines are successful prodrug principles for increasing the oral bioavailability of amidines (DE 10 2006 034 256.9). The esterification of the amidoximes or N-hydroxyguanidines with dicarboxylic acids and esters of the dicarboxylic acids which is proposed according to the invention, considerably 20 improves the solubility, in particular the solubility in aqueous media, and the bioavailability as compared to known prodrugs. The esterification of the amidoximes or N-hydroxyguanidines with dicarboxylic acids/dicarboxylic acid esters, due to the introduced negative charge of the deprotonated acid 25 function, represents a pole reversal as compared to benzamidine, an increased bioavailability and solubility in aqueous media is thus induced.

PCT/EP2009/051132 -5 The particular advantage of the compounds according to the invention is that they are present in the blood in a deprotonated form and so act as a substrate for the organic anion transporter (OAT), and thus exhibit a distinctly improved absorption from the gastrointestinal tract and 5 therefore increased bioavailability. Such organic anion transporters can consequently be enabled to pass the blood-brain barrier. This would be a decisive progress in the therapy of the African sleeping sickness, since the 2 phase of the disease can thus also be treated effectively. Furthermore, this esterification is to enable the blood-brain barrier to be passed. The compound 10 will be present in the blood in a deprotonated form so that it could constitute a substrate for the organic anion transporter (OAT) at the blood-brain barrier. Injectable dosage forms are also possible thanks to the introducing of carboxylic acids, since, just as in the case of amidines, the water solubility is restored. This applies in particular for the 15 case, where R 1 is hydrogen. According to the use according to the invention, the substituting of at least one or more amidine functions, N-hydroxyamidine (amidoxime) functions, guanidine functions or N hydroxyguanidine functions by the amidoxime dicarboxylic acid ester and N-hydroxyguanidine 20 dicarboxylic acid ester achieves for the solubility of the medicinal substance concerned to be increased. As a result, it can be firstly resorbed effectively after oral administration, and subsequently be reconverted again into the actual active form, the amidine, respectively, guanidine, by the body's own esterases and N-reductases (prodrug principle). The excellent resorbability of the modified amidoxime function or N-hydroxyguanidine function in the 25 gastrointestinal tract is obviously due to the increased solubility of the active agent molecules. Furthermore, the novel prodrug principles are capable of enabling the blood-brain barrier to be overcome. It is sufficient for the active agent to contain at least one or more active amidine functions, N 30 hydroxyamidine (amidoxime) functions, guanidine functions or N-hydroxyguanidine functions in the proposed form. The active agent consequently may contain, e.g., a plurality of amidoxime functions (e.g. two as in the case of pentoxime ester) or N-hydroxyguanidine functions, with at least one of these groups being then modified in the manner described above.

PCT/EP2009/051132 -6 Mixtures of active agents may be used just the same, provided that at least one active agent has one or more amidine functions, N-hydroxyamidine (amidoxime) functions, guanidine functions or N-hydroxyguanidine functions. The oral dosage form may be a liquid, semisolid or solid preparation, packaged in particular as a tablet, dragee, pellet or microcapsule. In this case, the 5 active agent or active agent mixture for embodiments of the type in which liquid preparations are used, is incorporated in a suitable non-toxic solvent such as water, monovalent alcohols, in particular ethanols, polyvalent alcohols, in particular glycerine and/or propanediol, polyglycols, in particular polyethylene glycols and/or miglyol, glycerol formal, dimethyl isosorbite, natural or synthetic oils. For producing semisolid or solid preparations, the usual base materials are 10 used such as bentonite, veegum, guar flour and/or cellulose derivatives, in particular methylcellulose and/or carboxymethyl cellulose, as well as polymers of vinyl alcohols and/or vinylpyrrolidones, alginates, pectins, polyacrylates, solid and/or liquid polyethylene glycols, paraffins, fatty alcohols, vaselines and/or waxes, fatty acids and/or fatty acid esters. 15 Moreover, in solid preparations, the extenders known per se, such as colloidal silicic acid, talc, lactose, starch powder, sugar, gelatine, metal oxides and/or metal salts may be contained. Stabilizers, emulsifiers, deflocculants and preservatives are suitable as further additives. The medicinal substances modified according to the use according to the invention exhibit an 20 excellent resorbability and thus bioavailability in oral administration, whereby the pharmacological effect of the amidine or guanidine is distinctly increased. As a result, an optimum dosage form for the oral application of amidines may be provided. The use according to the invention gains particular importance in that the functional groups 25 amidine and guanidine are essential constituents of various important active agents for different fields of application. Inter alia, they are a constituent of the following substance classes, respectively active agents: protease inhibitors (thrombin inhibitors such as melagatran, inhibitors of factor Xa, Factor VII, respectively of all of the proteases of the coagulation cascade; matriptase inhibitors), anticoagulants, thrombolytics, antifibrinolytics, DNA 30 intercalating and RNA-intercalating compounds (such as pentamidine, diminazene, isometamidium), N-methyl-D-aspartate receptor antagonists and inhibitors of viral enzymes (such as, e.g., neuraminidase inhibitors).

PCT/EP2009/051132 -7 Active agents containing an effective amidine function or guanidine function may be used inter alia for inhibiting blood coagulation, for the prophylaxis and therapy of visceral and cutaneous leishmaniasis, trypanosomiasis (African sleeping sickness), pneumonia caused by pneumocystis carinii (PCP), for inhibiting the growth of malign tumors, blood pressure reduction, 5 neuroprotection, and for combating viral infections such as influenza and HIV infections. The listings above are merely exemplary, and the invention basically encompasses any active agents, which have at least one amidine function or guanidine function that has been transferred into an improved prodrug according to the invention. The method according to the invention is 10 thus applicable to a very wide range of substance classes and indications and is capable of distinctly increasing the bioavailability of many medicinal substances, the active form of which contains an amidine or a guanidine. As examples for compounds modified according to the method according to the invention, 0 15 succinyl benzamidoxime, pentamidine succinic acid ester and diminazene succinic acid ester can be mentioned. The preparation according to the invention is explained in more detail by means of exemplary embodiments: 20 The preparation according to the invention is explained in more detail in the chapter Material and Methods by means of exemplary embodiments. Material and Methods 25 Exemplary embodiment 1: 0-succinyl benzamidoxime 0 O " OH NHO

NH

2 PCT/EP2009/051132 1.0 g of benzamidoxime was dissolved in 40 ml of anhydrous acetone. After adding 1.64 g of succinic acid anhydride, the mixture was stirred for four hours under reflux. The completeness of the reaction was checked by means of DC. After the end of the reaction, the solvent was withdrawn completely and the raw product recrystallized from toluene. 5 Yield: 82% Melting point: 151 C 10 IR (KBr): V = 3648, 3480, 3062, 2912, 1744, 1704, 1614, 1368 cm- 1 . 1 H-NMR (300 MHz, DMSO-d 6 ): 6/ppm (TMS) = 2.55 (t, 2H, 3 J = 6.9 Hz, CH 2 ), 2.69 (t, 2H, 3 J = 6.9 Hz, CH 2 ), 6.75 (s, 2H, 15 NH 2 ), 7.44 (m, 3H, Ar-H), 7.70 (m, 2H, Ar-H), 12.20 (s, 1H, COOH). "C-NMR (75 MHz, DMSO-d 6 ): 6/ppm (TMS) = 27.86 (CH 2 ), 28.72 (CH 2 ), 126.66 (CA 2.6), 128.26 (CA 3.5), 130.36 (CA 1), 131.59 (CA 4), 156.56 (C-NH 2 ), 170.19 (C=O), 173.50 (COOH). 20 MS (ESI): m/z (%) = 495 [2M+Na+H*] (100), 259 [M+Na+H*] (20), 237 [M+H*] (43), 137 [BAO+H*] (35), 121 [BA+H*] (13), 119 [C 4

H

6

O

4 +H*] (70). 25 C 11

H

12

N

2 0 4 (236.23): Ber. C 55.93% H 5.12% N 11.86% Gef. C 55.88% H 5.19% N 11.55% For proving the resorption from the gastrointestinal tract and the subsequent reduction to 30 benzamidine, the 0-succinyl benzamidoxime is selected as model compounds for the new prodrug principles and orally administered in each case to three rats. The metabolization of the ester into benzamidine in this case takes place in vivo as follows: PCT/EP2009/051132 -9 OH ,HN N N NH <ZYNH~ rrNNH N NH 2 hydrolysis N-reduction O-succinyl benzamidoxime benzamidoxime benzamidine 5 The metabolism of the diminazene succinic acid ester and pentamidine succinic acid ester is shown in the attached Figures 2 - 3. METHODS RELATED TO THE EXECUTION OF THE STUDY WITH RATS 10 The animal study was permitted by the Schleswig-Holstein Ministry of Agriculture, Environment and Rural Spaces on July 4, 2007. The anaesthesia was carried out using xylazine and ketamine. Both were administered by 15 intramuscular injection. The silicone catheters were implanted in the vena jugularis and the arteria carotis. They have locally antithrombotic and anti-inflammatory properties, but are not systemically active. During the surgery, the eyes were protected with a cornea-protective ointment (Oculotect*), and 3 - 4 ml of Ringer lactate solution was applied subcutaneously for improving the postoperative energy supply. The animals were treated antiphlogistically 20 (Finadyne*, 1 mg/kg of body weight) and antibiotically (Amoxicillin* 15%, 10 mg/kg of body weight) and postoperatively attended and kept warm until they woke up. The day after the surgery, the animals got Nutri plus, an energy paste (soy bean oil, molasses, cod-liver oil, meat extract, mineral premixture, vitamin premixture). 25 After the test was completed, the animals were euthanized using pentobarbital (i.v.). 30 PCT/EP2009/051132 - 10 KEEPING OF THE RATS Male Wistar rats having an average weight of 200 g served as the test animals. The animals were kept individually in cages. Every second day they got concentrated food. Water and dry 5 food was available ad libitum. APPLICATION OF THE SUBSTANCES For being able to determine the accurate dosage of the substances, the animals were weighed 10 the evening before the substance application. The substances (prodrugs) to be administered orally were applied via a stomach tube. For this purpose, 0-succinyl benzamidoxime was solved in 100 mM phosphate buffer, pH 8.5. The intravenously administered benzamidine was solved in 0.9% NaCl solution, so as to prevent haemolysis. After the injection, rerinsing with at least 0.5 ml of 0.9% NaCl solution was carried out. The substance application in each case took 15 place in the morning. The prodrugs were administered to three rats. Benzamidine was applied intravenously to two rats. The orally administered doses of O-succinyl benzamidoxime were 50 mg/kg of body weight. Benzamidine was applied in a concentration of 10 mg/kg of body weight. 20 BLOOD SAMPLING Six blood samples can be taken from one rat. The test period for one condition is one day. The blood samples were obtained over a period of eight hours after oral application, respectively six 25 hours after intravenous application. After the oral administration, the sampling took place after 30, 60, 90, 120, 240 and 480 minutes, after intravenous application after 5, 10, 20, 40, 80 and 360 minutes. Prior to the blood withdrawal, the catheter was emptied by a short aspiration until blood appeared. The blood withdrawal (300 [pl) was carried out by means of Multivetten (Multivetten* 600, Sahrstedt, Nimbrecht). For keeping the catheter clear, about 0.3 ml of a 30 mixture of heparin and NaCl were subsequently injected. The obtained full blood was centrifuged (1500 g, 10 min, 4'C). After the centrifugation, about 150 [pl plasma was taken as a supernatant, pipetted into Eppendorf cups and frozen at -80'C.

PCT/EP2009/051132 - 11 REPROCESSING OF THE BLOOD SAMPLES After slowly defrosting, 150 pl of plasma was diluted with Aqua bidest. ad 600 pl. The plasma samples were subsequently reprocessed by means of solid phase extraction. After conditioning 5 the column with 1000 pl of methanol and equilibrating with 1000 [I of Aqua bidest., the sample application (600 pl) was carried out. The sorbent was washed after the sample application with 600 pl of Aqua bidest. The elution of the substances was carried out by means of Aqua bidest., pH 3/methanol (6/4, V/V). Thereupon, the eluate is concentrated to dryness and absorbed with 100 fl of Aqua bidest./methanol (9/1, V/V) and transferred to the HPLC. 10 HPLC ANALYSIS FOR SEPARATING BENZAMIDOXIME AND BENZAMIDINE For separating the substances to be analyzed, the following HPLC method was used: 15 HPLC pump: Waters 600 Detector: Waters 2417 Tunable Absorbance Detector Autosampler: Waters 717 plus Autosampler Integrator: EZChromTM Elite Client/Server Version 2.8.3 Build 2249 recording and evaluation software 20 stationary phase: Synergy Max-RP 80A; 250* 4.6 mm with precolumn C 18 4.0* 3.0 mm (Phenomenex, Aschaffenburg) Column temperature: 24'C constant, by means of column heater Mobile phase: 10 mM of octyl sulfonate in Aqua bidest., pH 2.5 (with conc. H 3

PO

4 )/acetonitrile (82.5/17.5, V/V) 25 Run time: 30 minutes Detection: UV detector, 229 nm Flow rate: 1.0 ml/min Injection volume: 10pl Detector sensitivity: absorbance units fullscale: 2,000 30 Retention times: benzamidoxime: 23.5 ± 0.5 min benzamidine: 26.5 ± 0.5 min PCT/EP2009/051132 - 12 The eluant was filtered using a Satorius membrane filter (0.45 Pm) and degassed in an ultrasonic bath for 15 minutes. HPLC ANALYSIS FOR ANALYZING THE O-SUCCINYL BENZAMIDOXIME, 5 BENZAMIDOXIME AND BENZAMIDINE For separating the substances to be analyzed, the following HPLC method was used: HPLC pump: Waters 600 10 Detector: Waters 2417 Tunable Absorbance Detector Autosampler: Waters 717 plus Autosampler Integrator: EZChromTM Elite Client/Server Version 2.8.3 Build 2249 recording and evaluation software stationary phase: Synergy Max-RP 80A; 250* 4.6 mm with precolumn 15 C 18 4.0* 3.0 mm (Phenomenex, Aschaffenburg) Mobile phase: 100 mM phosphate buffer in Aqua bidest., pH 7.0 (with 30% KOH)/acetonitrile (92.8, V/V) Run time: 25 minutes Detection: 229 nm 20 Flow rate: 1.0 ml/min Injection volume: 10 1il Detector sensitivity: absorbance units fullscale: 2,000 Retention times: benzamidine: 5.3 ± 0.3 min O-succinyl benzamidoxime: 11.7 ± 0.3 min 25 benzamidoxime: 15.2 ± 0.3 min The eluant was filtered using a Sartorius membrane filter (0.45 tm) and degassed in an ultrasonic bath for 15 minutes. 30 The oral bioavailability of the benzamidine after oral administration of the O-succinyl benzamidoxime could be determined from the obtained data (Tab. 1): PCT/EP2009/051132 -13 Table 1: Bioavailability of the benzamidine after oral administration of 0-succinyl benzamidoxime bioavailability mean value standard deviation [%] [%] [%] Rat 4 19.9 Rat 10 36.1 31.6 10.2 Rat 21 38.7 5 As can be seen from the Table above, benzamidine has a bioavailability of 32% after oral administration of the 0-succinyl benzamidoxime. This demonstrates that the prodrug was completely resorbed after oral administration and reduced to the active form. The test results are represented in the attached drawings, which show in: 10 Fig. 1 the plasma level curves of benzamidine after oral application of 0-succinyl benzamidoxime, Fig. 2 the metabolism of he diminazene succinyl acid ester, and Fig. 3 the metabolism of the pentamidine succinyl acid ester. 15 Particular embodiments of the invention are: 1. Use of an amidoxime carboxylic acid ester of the formula (I) or an N hydroxyguanidine carboxylic acid ester of the formula (II) 20 ( OR 1 (1i) O OR N' N NH N NH2 2 H wherein n = 0, ... , 12, and R 1 is selected from the group consisting of hydrogen, an alkyl radical and an aryl radical and the salts thereof, as a substitute for one or more amidine functions, N- PCT/EP2009/051132 - 14 hydroxyamidine (amidoxime) functions, guanidine functions or N-hydroxyguanidine functions of a medicinal substance in drugs for improving the solubility, bioavailability and/or capacity of the medicinal substance to pass the blood-brain barrier. 5 2. Use according to embodiment 1, characterized in that the medicinal substance is selected from the group of protease inhibitors, DNA-intercalating and RNA-intercalating compounds, inhibitors of viral enzymes and N-methyl-D-aspartate receptor antagonists. 10 3. Use according to embodiment 2, characterized in that the protease inhibitor is a thrombin inhibitor, an inhibitor of factor Xa, Factor VII, or of all of the proteases of the coagulation cascade or a matriptase inhibitor. 4. Use according to embodiment 2, 15 characterized in that the protease inhibitor is an urokinase inhibitor. 5. Use according to embodiment 2, characterized in that the DNA-intercalating or RNA-intercalating compound is pentamidine, diminazene or isometamidium. 20 6. Use according to embodiment 2, characterized in that the inhibitor of viral enzymes is a neuraminidase inhibitor. 7. Use according to any one of the preceding embodiments, 25 characterized in that the medicinal substance is designed for the prophylaxis and therapy of visceral and/or cutaneous leishmaniasis, trypanosomiasis, the 2 phase of trypanosomiasis, or pneumonia caused by pneumocystis carinii, for inhibiting the growth of malign tumors, for inhibiting blood coagulation, for blood pressure reduction, for neuroprotection, and for combating viral infections including influenza and HIV infections. 30 - 14A Additional particular embodiments of the invention are: 1. Use of an amidoxime carboxylic acid ester of the formula (I) or an N 5 hydroxyguanidine carboxylic acid ester of the formula (II) O 0 OR 1 ) OR 1 N' N

NH

2 N NH 2 H wherein n = 0, ... , 12, and R 1 is selected from the group consisting of hydrogen, an alkyl radical and an aryl radical and the salts thereof, as a substitute for one or more 10 amidine functions, N-hydroxyamidine (amidoxime) functions, guanidine functions or N-hydroxyguanidine functions of a medicinal substance in drugs for improving the solubility, bioavailability and/or capacity of the medicinal substance to pass the blood brain barrier, characterized in that the medicinal substance is selected from the group of protease inhibitors, wherein the protease inhibitor is a thrombin inhibitor, an 15 inhibitor of factor Xa, Factor VII, or of all of the proteases of the coagulation cascade or a matriptase inhibitor, the DNA-intercalating and RNA-intercalating compounds, inhibitors of viral enzymes and N-methyl-D-aspartate receptor antagonists. 2. Use according to embodiment 1, characterized in that the DNA 20 intercalating or RNA-intercalating compound is pentamidine, diminazene or isometamidium. 3. Use according to embodiment 1, characterized in that the inhibitor of viral enzymes is a neuraminidase inhibitor. 25 4. Use according to any one of the preceding embodiments, characterized in that the medicinal substance is configured for the prophylaxis and therapy of - 14B visceral and/or cutaneous leishmaniasis, trypanosomiasis, the 2 phase of trypanosomiasis, or pneumonia caused by pneumocystis carinii, for inhibiting the growth of malign tumors, for inhibiting blood coagulation, for blood pressure reduction, for neuroprotection, and for combating viral infections including influenza 5 and HIV infections.

Claims (13)

1. A method for the prophylaxis and/or therapy of visceral and/or cutaneous leishmaniasis, trypanosomiasis, the 2 "d phase of trypanosomiasis, or pneumonia caused by pneumocystis carinii, for inhibiting the growth of malign tumors, for inhibiting blood coagulation, for blood pressure reduction, for neuroprotection, and for combating viral infections including influenza and HIV infections, wherein the method comprises administering to a subject a drug comprising a partial structure forming formula (I) or formula (II) N' wherein the partial structure is a constituent of the overall structure of the drug, wherein the drug comprises a prodrug for a medicinal substance, wherein n = 0, ... , 12 and R1 is selected from the group consisting of hydrogen, an alkyl radical and aryl radical.

2. Method according to claim 1, wherein the partial structure of formula (I) or (II) is used as a substitute for one or more amidine functions, N-hydroxyamidine (amidoxime) functions, guanidine functions or N-hydroxyguanidine functions of a medicinal substance in drugs for improving the solubility, bioavailability and/or - 16 capacity of the medicinal substance to pass the blood-brain barrier.

3. Method according to claim 1 or 2, wherein the medicinal substance is selected from the group of protease inhibitors, wherein the protease inhibitor is a thrombin inhibitor, an inhibitor of factor Xa, Factor VII or of all of the proteases of the coagulation cascade, or a matriptase inhibitor, of DNA-intercalating and RNA intercalating compounds, inhibitors of viral enzymes and N-methyl-D-aspartate receptor antagonists.

4. Method according to at least one of the preceding claims, wherein the overall structure of the drug comprises a plurality of partial structures of formula (I) and/or (II).

5. Method according to at least one of the preceding claims, characterized in that the DNA-intercalating or RNA-intercalating compound is pentamidine, diminazene or isometamidium.

6. Method according to at least one of the preceding claims, characterized in that the inhibitor of viral enzymes is a neuraminidase inhibitor.

7. Method according to at least one of the preceding claims, characterized in that the drug is pentamidine succinic acid ester.

8. Prodrug comprising a partial structure having the formula (I) or (II) H ~'< NH2 - 17 wherein n = 0, ... , 12, and Ri is selected from the group consisting of hydrogen, an alkyl radical and an aryl radical, when used as a prodrug for a medicinal substance.

9. Prodrug according to at least claim 8, characterized in that the medicinal substance is configured for the prophylaxis and/or therapy of visceral and/or cutaneous leishmaniasis, trypanosomiasis, the 2 "d phase of trypanosomiasis, or pneumonia caused by pneumocystis carinii, for inhibiting the growth of malign tumors, for inhibiting blood coagulation, for blood pressure reduction, for neuroprotection, and for combating viral infections including influenza and HIV infections.

10. Prodrug according to at least one of claims 8 or 9, wherein the overall structure of the prodrug comprises a plurality of partial structures of formula (I) and/or (II).

11. Prodrug according to at least one of claims 8 - 10, wherein the prodrug is pentamidine succinic acid ester.

12. A pharmaceutical composition comprising the prodrug according to any one of claims 8 to 11 and a pharmaceutically acceptable carrier, when used as a prodrug for a medicinal substance.

13. A method for the prophylaxis and/or therapy of visceral and/or cutaneous leishmaniasis, trypanosomiasis, the 2 "d phase of trypanosomiasis, or pneumonia caused by pneumocystis carinii, for inhibiting the growth of malign tumors, for inhibiting blood coagulation, for blood pressure reduction, for neuroprotection, and for combating viral infections including influenza and HIV infections, wherein the method comprises administering to a subject the prodrug according to any one of claims 8 to 11 or the pharmaceutical composition according to claim 12.