our experiments led us to a non - excepted finding of an aqueous solvent system capable of dissolving hydrophobic pharmaceutically active agents in therapeutically effective amounts . the substantial solubilizing effect of these solvent systems is based on the synergistic solubilizing effect of the applied ingredients . the compositions which are based on the present solvent system comprise a therapeutically active agent and the solvent system . the solvent system comprises water , a ph - adjuster ( i . e . an acid or a base ), a co - solvent and a surfactant . these solvent system are readily capable of solubilizing various types of active agents which are hydrophobic , i . e . sparingly , slightly , very slightly soluble or practically insoluble , or non - soluble in water . the pharmaceutically active agent can be any azole type molecule ( azole derivative ). preferably the active agent is an antifungal agent . such azole derivatives are for example azanidazole , bifonazole , butoconazole , clomidazole , clotrimazole , eberconazole , econazole , fluconazole , flutrimazole , genaconazole itraconazole , ketoconazole , miconazole , omoconazole , ornidazole , oxiconazole , posaconazole , ravuconazole , saperconazole , sertaconazole , sulconazole , terconazole , tiabendazole , tioconazole , voriconazole or their salts . even more preferably the antifungal agent is ketoconazole or miconazole or their salts . it should be understood that the list is merely illustrative and any analogue or derivative or a mixture of the stated molecules are included within the scope of the present invention . the solvent system that is able to solubilize and keep in solution the previously mentioned therapeutically active agents is a complex solution comprising of water , a ph - adjuster ( i . e . acid or base ) or its salts , a co - solvent and a surfactant . the amount of water present in the solvent system or composition according to the present invention is of utmost importance in aspect of the applicability and in aspect of its administration to patients . in compositions where the therapeutically effective amount of pharmaceutically active agent cannot be dissolved in water alone , adequate amounts of solubilizing excipients such as co - solvents or surfactants can be used . it is well known for a skilled person in the art that the amount of organic or non - aqueous solvents or excipients replacing water in a dosage form [ especially in parenteral ( intravenous ) dosage forms ] is limited due to the toxicity of these excipients . the determination of the amount of the water to be present in a composition is based on benefit / risk assessments ( taken into consideration the composition of previously registered products ). of course , a skilled person intends to apply as little amount of toxic excipients as possible . based on such considerations it is proposed that the solvent systems according to the present invention should comprise 1 - 99 % water , preferably 50 - 90 % water , more preferably 60 - 80 % by volume water . in case of parenteral administration , of course , the water is preferably a so - called “ water for injection ”. the term ph - adjuster relates to an acid or base , or their salts or a mixture thereof throughout the entire specification . an acid or a base according to bronsted - lowry is a molecule capable of donating or accepting a proton ( hydrogen ion ), respectively . due to their previously stated property , acids and bases adjust the ph of the solution in which they are in to 0 - 7 , if they are acidic , and to 7 - 14 , if they are basic . without getting bound to a theory it can be said that the solubility of weakly acidic or basic compounds depends mainly on their intrinsic solubility , pka and the ph of its environment . this can be expressed by the henderson - hasselbach equation . therefore , the solubility of drugs with ionizable groups can be considerably altered by means of ph adjustment . it is known to a skilled person that the acceptable range for parenteral administration is determined by the buffer capacity of the blood and preferably it is ph 3 - 8 . any injectable composition having a ph outside this range may cause irritation , tissue damage and pain on administration ; therefore it should be administered with care . preferably , a pharmaceutical composition falling into the preferred range should be formulated . based on the previous theory the acids and bases used in the present invention include , but are not limited to organic or inorganic acids or bases , acids or bases which are salts of pharmaceutically acceptable bases or acids , respectively , and the mixtures thereof . more preferably , the acids include , but are not limited to boric acid , hydrochloric acid , hydrobromic acid , hydroiodic acid , nitric acid , phosphoric acid , sulfuric acid , acetic acid , amino acids , ascorbic acid , benzoic acid , carbonic acid , citric acid , formic acid , gluconic acid , lactic acid , maleic acid , propionic acid , salicylic acid , tartaric acid , thioglycolic acid and uric acid . in the present invention salts of the preferred acids also can be applied , where the cationic part of them can be , but not limited to ammonium , calcium , lithium , magnesium , potassium and sodium ion . bases used in the present invention are , but not limited to hydroxides , carbonates , hydrocarbonates , silicates of the previously listed cations and triethanolamin and their analogues . it should be understood that the list is merely illustrative and any analogue or derivative or a mixture of the stated molecules are within the scope of the present invention . co - solvents are pharmaceutically acceptable excipients used beside water to solubilize poorly soluble molecules . co - solvents are added to the aqueous solution at a chosen percentage and thus the dielectric constant of the resulting solvent systems decreases . this phenomenon and the ability of the co - solvents to disrupt the secondary bonding structure of water results in their capability of solubilizing poorly soluble therapeutically active agents . these solvents are mainly organic and as such have to be used with certain limitations due to their ability to cause precipitation , inflammation and pain at the site of injection . as already discussed above , to avoid such side effects the lowest possible , but suitable amount of excipient is required . in an embodiment of the present invention the co - solvents are for example alcohols , preferably c1 - c6 alcohols , more preferably c1 - c4 alcohols , even more preferably ethyl - alcohol , propylene glycol , glycerol ; ethers , more preferably ethers of polyethylene glycols , even more preferably ethers of polyethylene glycols of molecular mass 200 - 6000 , even more preferably polyethylene glycol 400 ; amides ; esters and other solubilizers known in the art . it should be understood that the list is merely illustrative and any analogue or derivative or a mixture of the mentioned molecules are within the scope of the present invention . the amount of the co - solvent is 1 - 80 %, preferably 10 - 50 %, more preferably 15 - 30 % by volume . surfactants are a valuable group of excipients also used in water for the solubilization of therapeutically active hydrophobic entities , more preferably sparingly , slightly , very slightly soluble or practically insoluble , or non - soluble therapeutically active agents . to serve as a surfactant the compound must have a hydrophilic and a hydrophobic part . based on their structure one can differentiate non - ionic , ionic and hydrophobic surfactants , but irrelevant of their structure all surfactants can form micelles in an aqueous solution if they are present in an adequate amount . these micelles are then capable of solubilizing molecules either by entrapping the molecule in the micelle or by other means of bonding to the therapeutically active agent . in a embodiment of the present invention the surfactant can be from the group of polyethoxylated fatty acids , peg fatty acid esters , polyethylene glycol glycerol fatty acid esters , alcohol - oil transesterification products , polyglycerized fatty acids , propylene glycol fatty acid esters , mono - and diglycerides , sterol and sterol derivatives , polyethylene glycol sorbitan fatty acid esters , polyethylene glycol alkyl ethers , sugar esters and sorbitan fatty esters or ionic surfactant . more preferably from the group of polyethylene glycol sorbitan fatty acid esters or ionic surfactant , even more preferably polysorbates or a derivative of choleate , even more preferably polysorbate 20 , 60 , 80 , most preferably polysorbate 80 , or sodium taurocholeate or a combination thereof . it should be understood that the list is merely illustrative and any analogue or derivative or a mixture of the mentioned molecules are within the scope of the present invention . the amount of the surfactant can be 0 . 01 to 10 %, preferably 0 . 1 to 5 %, most preferably 3 % by weight . the following examples illustrate and describe the present invention through some preferred embodiments without the intention to limit the scope claimed . each of the solutions applied in the solubilization tests were prepared as follows ( the specific amount of the components comes from the tables below ): 1 . 0 . 05m ammonium acetate ( as ph - adjuster ) solution was prepared in a volumetric flask and the ph of this solution was set to ph 3 . 1 with glacial acetic acid . 2 . the specific amount of co - solvent was measured into a beaker and the specific amount of the previously prepared 0 . 05m ammonium acetate solution was added . the ph of this solution was measured and set to ph 3 . 1 with glacial acetic acid . 3 . the specific amount of surfactant was added to the solution . 4 . this solvent system was vigorously shaken until complete homogenization of the solution was achieved . 5 . aliquot amount of this solvent system was measured and the specific amount of the active agent was added to the solution . the tables below define the composition of each solution tested and the amount of the active agent which could be solubilized by the applied solvent system . the amount of the co - solvent is given in % by volume and the amount of the surfactant is given in % by weight in each table . in order to justify our previous statement , according to which the solvent system exhibits a synergistic solubilizing effect , the solubility of miconazole was measured separately in ph adjusters , co - solvents and surfactants , i . e . in the components of the solvent system . the results are given in table 1 . these data can be used for comparison with tables 2 and 3 wherein the results were obtained by the solvent system according to the invention . the synergistic effect means that the solubility enhancer effect of the combination applied [ ph - adjuster ( s ), co - solvent ( s ) and surfactant ( s )] is more than the sum of the solubilizing effect of each excipient applied separately . tables 2 and 3 show the solubilizing effect of various combinations of a ph adjuster , co - solvent ( s ) and surfactant ( s ). as it can be seen , surprisingly , adding the solubilized amount of miconazole in 0 . 05 m ammonium acetate , in 25 % ethanol and in 3 % polysorbate gives a much lower value than the measured value in case of the solvent system where the mentioned components are applied together . as it was discussed in the detailed description of the invention , it is advantageous to reduce the amount of excipients in a parenteral dosage form as much as possible . tables 2 and 3 show the results of the experiments performed to comply with these requirements . table 2 shows the results of the study of the effect of various concentrations of polysorbate 80 on the solubility of miconazole in a solvents system comprising polysorbate 80 , 25 % ethanol and ammonium acetate at ph 3 . 1 . as it can be seen , surprisingly , the obtained solubility results showed that reducing the quantity of the surfactant ( polysorbate 80 ) did not result in substantial loss of solubilizing capability . in the next phase of the experiments the amount of the co - solvent ( ethanol ) was reduced . the solubility test results of miconazole are shown in table 3 obtained in a solvent system comprising 0 . 1 % polysorbate 80 , various concentrations of ethanol and ammonium acetate ( ph 3 . 1 ). as it can be seen , reducing the amount of the co - solvent ethanol from 25 % to 20 % had negligible effect but further decreasing had significantly negative effect on the solubilizing capability of the solvents system . it should also be noted that further increasing the amount of ethanol is not advisable on toxicological issues previously discussed . these compositions were autoclaved and showed excellent stability . here we would mention that the sterility can be achieved by membrane filtration ( applying proper pore size and compatible conditions ). a composition called as “ concentrate for infusion ” should be diluted before administration to patients by a previously determined amount of usual infusion . the usual infusion is chosen preferably from the group of 5 % dextrose infusion and 0 . 9 % sodium chloride infusion . it is well known for a skilled person in the art that such a dilute should be stable for at least 48 hours . to reproduce the dilution scheme applied in the case of monistat ® ( previously marketed as a concentrate for infusion containing miconazole ), one of the compositions of the present invention was diluted with 5 % dextrose infusion and 0 . 9 % sodium chloride infusion . based on the previous results a composition comprising of 0 . 1 % polysorbate 80 , 20 % ethanol and ammonium acetate ph 3 . 1 was chosen for further investigation . 10 ml of the chosen composition containing 20 mg / ml of miconazole was diluted to 200 ml with 5 % dextrose infusion or 0 . 9 % sodium chloride infusion . since this composition was not stable for 48 hours , further investigations were performed . it was found that , depending on the amount of miconazole solubilized in the composition , various concentrations of surfactants are necessary to keep the active agent solubilized on dilution . table 4 shows the amount of surfactant necessary to solubilize various concentrations of miconazole on dilution to 200 ml with 5 % dextrose or 0 . 9 % sodium chloride infusions . on the basis of the above results it was established that concentration of the surfactant can be 0 . 01 to 10 %, preferably 0 . 1 to 5 %, most preferably 3 %. table 5 contains further solubilizing compositions and the measured concentrations of miconazole , ketoconazole and itraconazole . the compositions presented below comprise of 3 % surfactant , 25 % co - solvent and ph adjuster ( ph 3 . 1 ). the first composition is thought to be the most suitable for miconazole . further compositions were prepared to find solvent systems showing even better solubilizing capability . as it can be seen , very surprisingly , although all three compounds are azole derivatives and show significant similarity in respect of their chemical structure but their solubility differs greatly in the compositions listed above . ketoconazole showed the best solubility in the compositions , followed by miconazole , which also showed a remarkable solubility . the amounts of both of these active agents solubilized in the compositions are therapeutically significant and can be conveniently applied to formulate a concentrate for infusion . on the other hand , itraconazole showed no substantial solubility in the compositions of the present invention . u . s . pat . no . 6 , 383 , 471 discloses several compositions comprising a hydrophobic therapeutically active agent containing at least one ionizable functional group , an ionizing agent , a solubilizer and a surfactant and the method of producing the same . a few examples using itraconazole and tretinoin as the hydrophobic therapeutically active agent are disclosed and their stability upon dilution with gastric and intestinal fluid is also thought . examples 27 - 31 are detailed in the background of the invention . it is also disclosed in the patent that compositions 27 to 31 are capable of dissolving 85 , 50 , 50 , 30 and 30 mg / ml of itraconazole respectively . these compositions comprise no water and , as stated before , the amount of water present in a pharmaceutical composition , especially in parenteral dosage forms , is of utmost importance . no data concerning the stability of these compositions on autoclaving or membrane filtration are given and parenteral route of administration is one of the least preferable ways of administration according to the patent . present invention describes solvent systems exerting synergistic solubilizing effect on hydrophobic azole derivatives . in order to compare the solubilizing effect of the solvent system of the present invention and the same of u . s . pat . no . 6 , 383 , 471 , the solvent systems of examples 27 - 31 of this patent were reproduced . table 6 shows the data of obtained by these solvent systems in case of miconazole , ketoconazole and itraconazole . the solubilizing effect of the solvent system of the present invention is shown in table 5 . it should be noted again that the compositions according to the present invention contain preferably about 70 % of water . to have a proper base for comparison with the compositions of u . s . pat . no . 6 , 383 , 471 they should be diluted with water to 70 % of water content . the accordingly calculated solubilizing effect of solving systems of examples 27 - 31 from u . s . pat . no . 6 , 383 , 471 are shown in table 7 . comparing the data of table 7 with the data of table 5 it can be seen that the solvent systems of the present invention exert a greater solubility increase in the case of miconazole and a surprisingly much greater solubility increase in the case of ketoconazole . it is also shown that although itraconazole shows substantial chemical similarity to miconazole and ketoconazole , surprisingly , the compositions of the present invention do not exert a substantial solubility enhancing effect on its solubility , compared to the compositions in u . s . pat . no . 6 , 383 , 471 . summarizing the results of the invention it can be concluded that the compositions of the present invention exert a substantial synergistic solubilizing effect on a group of pharmaceutically active agents , namely on antifungicide azole derivatives . the compositions of the present invention comply with all the requirements set against parenteral ( preferably injectable ) compositions . in more detail , the solvent system contains water which , as it was detailed above , is a very important component in parenteral dosage forms . all the other components mentioned above are pharmaceutically acceptable in parenteral dosage forms . this acceptability also concerns the quantity of applied components . it is also shown that the compositions of the present invention can be sterilized either by autoclaving or sterile membrane filtration . it is also shown that the compositions can be diluted into large volume and these diluted compositions are applicable in parenteral administration .
a pharmaceutical composition includes : an azole derivative solubilized in a solvent system including : a ) water , b ) ph - adjuster , c ) co - solvent and d ) surfactant .