WO2010100199A1

WO2010100199A1 - Fluconazole carboxylic ester derivatives, synthesis, and use in long acting formulations

Info

Publication number: WO2010100199A1
Application number: PCT/EP2010/052708
Authority: WO
Inventors: Yves Rene Johanna Paul Gonnissen
Original assignee: Seps Pharma N.V.
Priority date: 2009-03-05
Filing date: 2010-03-03
Publication date: 2010-09-10
Also published as: GB0903818D0; WO2010100186A1

Abstract

This invention relates to compounds represented by the structural formula (1) and the salts, N-oxides, quaternary amines, and stereoisomers thereof, wherein: R' is a saturated or ethylenically unsaturated linear or branched alkylene group having from 2 to 4 carbon atoms or a saturated or ethylenically unsaturated cycloalkylene group having from 4 to 8 carbon atoms, and OY is a sterol residue. These compounds are useful pharmaceutical agents with improved solubility and bioavailability characteristics.

Description

FLUCONAZOLE CARBOXYLIC ESTER DERIVATIVES, SYNTHESIS, AND USE IN LONG ACTING FORMULATIONS

Field of the invention

The invention relates to organic chemistry, and in particular to prodrugs and pharmaceutical formulations.

Background of the invention Fluconazole, also known as Diflucan ®, is a triazole antifungal agent firstly described in UK patent application 2099818 (Pfizer Limited). It is used worldwide for the treatment of infections due to Candida, Cryptococcus, and other opportunistic yeasts or fungi. The drug is available as a tablet (50, 100, or 200 mg), as an oral suspension, and as an intravenous formulation (200 or 400 mg). When used in the treatment of invasive candidiasis, e.g., bloodstream infections, deep tissue sites, or other normally sterile site infections, fluconazole is administered as an initial loading dose of 800 mg (oral or intravenous) followed by a daily maintenance dose of 400 mg (oral or intravenous). Higher daily doses of 800 mg or greater may be used in selected circumstances (J. Infect. 1993, 16:133-146. Clin. Infect. Dis. 2004, 38:161-189. Clin. Infect. Dis. 2003, 36:1221-1228. Eur. J. Clin. Microbiol. Infect. Dis. 1999, 18:165-174).

Daily maintenance doses of fluconazole are a serious constraint to the effective treatment of fungal infections. Such dosage schedules lead to a higher workload for clinical personnel and more importantly, poor patient compliance, thereby increasing the probability of administering suboptimal doses, ultimately contributing to the emergence of resistant fungal strains. It has been established that reduced access of the drug to the target enzyme, the fungal cytochrome P- 450-dependent enzyme lanosterol 14-α-demethylase, is one of the mechanisms that produce resistance in Candida albicans (Clin. Microbiol. Rev. 1999, 12:501-517). Also, exposure of C. glabrata to subtherapeutic doses (i.e., <400 mg/day) of fluconazole may result in resistance not only to fluconazole but to other azoles (i.e., itraconazole and voriconazole) as well (Antimicrob. Agents Chemother. 2005, 49:783-787). It is also interesting to note that overexpression of the target enzyme encoding gene ERGIl results in the production of high concentrations of the target enzyme, creating the need for higher intracellular fluconazole concentrations to inhibit all of the enzyme molecules in the cell.

When patient compliance is a problem, long acting dosage forms of medication is a possible solution, where a single administration leads to a sustained release of the medication over an extended period of time. Such dosage forms simplify the regimen that a patient needs to adhere to, thereby reducing the probability of non-compliance as occurs with a more rigorous schedule. There is a need in the art for improving fluconazole solubility in the most common classes of pharmaceutical solvents in order to achieve stable emulsions or suspensions.

Therefore, toxicity concerns, limited antifungal spectrum, and the emergence of fungi resistant to currently available agents have created a need for new antifungal agents effective against life- threatening systemic mycoses caused by C. neofornans, Aspergillus species, and Candida species.

Chinese patent no. 101279953 discloses a triazole derivative of formula R'-OOC-R-COOH (I) or its medicine salt, having good water-solubility, and acting as fungicide, wherein R¹ is the non- hydroxy part of a triazole antimicrobial compound which has tert-hydroxyl, R is -(CH₂)D-, and n is 2-4.

WO2005/006860 (Board of Governors, State of Rhode Island and Providence Plantations) discloses compounds wherein a fluconazole residue is directly linked to a hydro carbylcarbonyl moiety, wherein said hydrocarbyl may be alkyl, aryl, alkenyl, alkynyl, alkyl halide, alkoxy or aryloxy.

Nguyen-Hai Nam et al. (Bioorg Med Chem. 2004 Dec 1; 12(23):6255-69) disclose carboxylic acid derivatives of fluconazole, synthesis, and antifungal activities.

It is an object of the present invention to provide fluconazole derivatives and formulations that deliver the drug over a sustained period of time at concentrations efficacious for treatment of mammals including humans. Such fluconazole forms and formulations must be safe, i.e. having minimal side effects, and with appropriate pharmacokinetic profiles.

It is an object of the present invention to provide fluconazole derivatives and formulations that can improve one or more of the following pharmacokinetic parameters in respect of the currently available formulations: a longer half- life, increased volume of distribution, extended drug release, sustained plasma concentration, or a longer duration of action.

It is an object of the present invention to provide derivatives and formulations of fluconazole in high loading doses when compared to the currently available formulations. It is an object of the present invention to provide chemically stable derivatives of fluconazole. It is a further object of the present invention to provide chemically stable formulations of fluconazole. It is also an object of the present invention to provide soluble derivatives of fluconazole

It is an object of the present invention to minimize the number of doses of fluconazole to be administered. It is an object of the present invention to provide fluconazole derivatives or formulations that allow bolus injection. It is another object of the present invention to provide fluconazole depots in a patient.

It is an object of the present invention to provide fluconazole injectable formulations with a suitable volume that avoids painful administration.

It is an object of the present invention to provide derivatives and formulations of fluconazole that can reduce the emergence of resistant fungal strains.

It is an object of the present invention to provide derivatives and formulations of fluconazole that can increase intracellular fluconazole concentrations.

Summary of the invention

The present invention is based on the surprising finding that fluconazole can be derivatized, onto the tertiary alcohol group, with specific carbonyl-containing moieties which significantly modify its physico-chemical properties, in particular its water-solubility under physiological conditions. This significant modification allows its inclusion in complex types of pharmaceutical formulations such as, but not limited to, microemulsions, microsuspensions and nanosuspensions resulting in completely modified and novel bioavailability profiles that opens up the generation of novel treatment schedules which were not possible with the parent tertiary alcohol. The derivatives of this invention contain a sterol residue attached to a tertiary alcohol residue through a linker having two carbonyl groups. . The present invention also provides injectable forms of fluconazole which until now were impossible to achieve due to their inherent poor water solubility.

Description of the invention

As used herein with respect to a substituent, and unless otherwise stated, the term "Ci_4 alkyl" refers to a straight or branched chain saturated acyclic hydrocarbon monovalent group having from 1 to 4 carbon atoms such as, for example, methyl, ethyl, propyl, n-butyl, 1-methylethyl (isopropyl), 2-methylpropyl (isobutyl) and 1,1-dimethylethyl (tert-butyi); the term "Ci_6 alkyl" additionally refers to similar groups having up to 6 carbon atoms such as, for example, 2-methyl- butyl, n-pentyl, dimethylpropyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, and the like.

As used herein, and unless otherwise stated, the term "Ci_6 alkoxy" refers to a substituent wherein a carbon atom of a Ci_6 alkyl group (such as defined herein-above), is attached to an oxygen atom through a single bond such as, but not limited to, methoxy, ethoxy, propoxy, butoxy, pentoxy, isopropoxy, sec-butoxy, tert-butoxy and isopentoxy.

As used herein with respect to a substituent, and unless otherwise stated, the term "C3_i2 cycloalkyl" refers to a mono- or polycyclic saturated hydrocarbon monovalent group having from 3 to 12 carbon atoms, such as for instance cyclopropyl, eye Io butyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cycloundecyl, cyclododecyl and the like, or a C₇-Io polycyclic saturated hydrocarbon monovalent radical having from 7 to 10 carbon atoms such as, for instance, norbornyl, fenchyl, trimethyltricycloheptyl or adamantyl.

As used herein with respect to a linker, and unless otherwise stated, the term "alkylene" refers to the straight or branched chain saturated acyclic hydrocarbon divalent group corresponding to an alkyl by abstracting a hydrogen atom.

As used herein with respect to a linker, and unless otherwise stated, the term "cycloalkylene" refers to the mono- or polycyclic saturated hydrocarbon divalent group corresponding to a cycloalkyl by abstracting a hydrogen atom.

As used herein with respect to a substituent, and unless otherwise stated, the term "halogen" refers to any one of fluoro, chloro, bromo and iodo.

As used herein with respect to a substituent, and unless otherwise stated, the term "C3_8 alkenyl" refers to a straight or branched chain ethylenically mono- or poly-unsaturated acyclic hydrocarbon monovalent group having from 3 to 8 carbon atoms such as, for example, allyl, methallyl, crotyl, prenyl, geranyl and the like.

As used herein, and unless otherwise stated, the term "electron-withdrawing" refers to the tendency of a substituent to attract valence electrons of the molecule of which it is apart, i.e. it is electronegative, such as but not limited to cyano, sulfo, nitro, halo or the like. As used herein with respect to a substituent, and unless otherwise stated, the term "heterocyclyl" refers to a mono- or polycyclic, monovalent hydrocarbon group having from 2 up to 15 carbon atoms and including one or more heteroatoms in one or more heterocyclic rings, each of said rings having from 3 to 10 atoms (and optionally further including one or more heteroatoms attached to one or more carbon atoms of said ring, for instance in the form of a carbonyl or thiocarbonyl or selenocarbonyl group, and/or to one or more heteroatoms of said ring, for instance in the form of a sulfone, sulfoxide, N-oxide, phosphate, phosphonate or selenium oxide group), each of said heteroatoms being independently selected from the group consisting of nitrogen, oxygen, sulfur, selenium and phosphorus.

The term "tertiary alcohol residue" as used herein, unless otherwise stated, refers to the residue obtained after abstraction of the hydrogen of the hydroxyl group of a tertiary alcohol.

The term "tertiary alcohol" as used herein, unless otherwise stated, refers to any compound having a hydroxyl group directly attached to a carbon atom having no hydrogen atom attached thereto.

The term "sterol residue" as used herein, unless otherwise stated, refers to the residue obtained after abstraction of the hydrogen of the hydroxyl group of a sterol.

The term "sterol" as used herein, unless otherwise stated, refers to a steroid alcohol with a hydroxyl group at the 3 -position of the A ring of said steroid.

In a first aspect the present invention relates to a compound represented by the structural formula

(1) and the salts, N-oxides, quaternary amines, and stereoisomers thereof, wherein: R' is a saturated or ethylenically unsaturated linear or branched alkylene group having from 2 to 4 carbon atoms or a saturated or ethylenically unsaturated cycloalkylene group having from 4 to 8 carbon atoms, and

- OY is a sterol residue.

Specifically useful embodiments of this first aspect of the present invention include, but are not limited to, these wherein:

- said sterol residue OY is a zoosterol residue; said sterol residue OY is a phyto sterol residue; - said sterol residue OY is an ergosterol residue; said sterol residue OY is selected from the group consisting of cholesterol residue, cholestanol residue, campesterol residue, lanosterol residue, sitosterol residue, stigmasterol residue, and cycloartenol residue;

- R' is (CH₂)_n or - CHC(CH₃) - (CH₂)_n, and n is 2, 3 or 4; - R' is selected from the group consisting of - CH = CH - , - CH = C(CH₃) - , - CH -

C(=CH₂) -, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, cyclopentenylene, cyclohexenylene and phenylene; or compound of structural formula (1) is 2-(2,4-difluorophenyl)-l,3-di(lH-l,2,4-triazol-l- yl)propan-2-yl (3S,8S,9S, 1 OR, 13R, 14S, 17R)- 10, 13-dimethyl- 17-((R)-6-methylheptan-2-yl)- 2,3,4,7,8,9,10,11,12,13, 14,15, lβJV-tetradecahydro-lH-cyclopentaf^phenanthren-S-yl succinate.

Several specific embodiments as described herein-above may be combined independently together, especially with respect to the choice of R' and OY.

It should be noted that the radical positions on any molecular moiety used in the definitions may be anywhere on such moiety as long as it is chemically stable. When any variable occurs more than one time in any moiety, each definition is independent. Radicals used in the definitions of the variables include all possible isomers unless otherwise indicated. For instance pentyl includes 1 -pentyl, 2-pentyl and 3 -pentyl.

Whenever used hereinafter, the term "compounds of formula (I)", or "the present compounds" or similar terms, it is meant to include the compounds of formula (1), the salts thereof; and the stereochemically isomeric forms thereof. The compounds of formula (1) may have several centers of chirality, particularlyin respect to the sterol residue, and exist as stereochemically isomeric forms. The term "stereochemically isomeric forms" as used herein defines all the possible compounds made up of the same atoms bonded by the same sequence of bonds but having different three-dimensional structures which are not interchangeable, which the compounds of formula (1) may possess. With reference to the instances where (R) or (S) is used to designate the absolute configuration of a chiral atom within a substituent, the designation is done taking into consideration the whole compound and not the substituent in isolation.

Unless otherwise mentioned or indicated, the chemical designation of a compound encompasses the mixture of all possible stereochemically isomeric forms, which said compound might possess. Said mixture may contain all diastereomers and enantiomers of the basic molecular structure of said compound. All stereochemically isomeric forms of the compounds of the present invention both in pure form or mixed with each other are intended to be embraced within the scope of the present invention.

Pure stereoisomeric forms of the compounds and intermediates as mentioned herein are defined as isomers substantially free of other enantiomeric or diastereomeric forms of the same basic molecular structure of said compounds or intermediates. In particular, the term "stereoisomerically pure" concerns compounds or intermediates having a stereoisomeric excess of at least 80% (i.e. minimum 80% of one isomer and maximum 20% of the other possible isomers) up to a stereoisomeric excess of 100% (i.e. 100% of one isomer and none of the other), more in particular, compounds or intermediates having a stereoisomeric excess of 90% up to 100%, even more in particular having a stereoisomeric excess of 94% up to 100% and most in particular having a stereoisomeric excess of 97% up to 100%. The terms "enantiomerically pure" and "diastereomerically pure" should be understood in a similar way, but then having regard to the enantiomeric excess, and the diastereomeric excess, respectively, of the mixture in question.

Pure stereoisomeric forms of the compounds and intermediates of this invention may be obtained by the application of art-known procedures. For instance, enantiomers may be separated from each other by the selective crystallization of their diastereomeric salts with optically active acids or bases. Examples thereof are tartaric acid, dibenzoyltartaric acid, ditoluoyltartaric acid and camphorsulfonic acid. Alternatively, enantiomers may be separated by chromatographic techniques using chiral stationary phases. Said pure stereochemically isomeric forms may also be derived from the corresponding pure stereochemically isomeric forms of the appropriate starting materials, provided that the reaction occur stereospecifically. Preferably, if a specific stereoisomer is desired, said compound will be synthesized by stereospecifϊc methods of preparation. These methods will advantageously employ enantiomerically pure starting materials.

The diastereomeric racemates of the compounds of formula (1) can be obtained separately by conventional methods. Appropriate physical separation methods that may advantageously be employed are, for example, selective crystallization and chromatography, e.g. column chromatography.

The present invention is also intended to include all isotopes of atoms occurring on the present compounds. Isotopes include those atoms having the same atomic number but different mass numbers. By way of general example and without limitation, isotopes of hydrogen include tritium and deuterium. Isotopes of carbon include C-B and C-14.

For therapeutic use, salts of the compounds of formula (1) are those wherein the counter-ion is pharmaceutically acceptable, which salts can be referred to as pharmaceutically acceptable acid and base addition salts. However, salts of acids and bases that are non-pharmaceutically acceptable may also find use, for example, in the preparation or purification of a pharmaceutically acceptable compound. All salts, whether pharmaceutically acceptable or not, are included within the ambit of the present invention.

The pharmaceutically acceptable acid and base addition salts as mentioned hereinabove are meant to comprise the therapeutically active non-toxic acid and base addition salt forms that the compounds of formula (1) are able to form. The pharmaceutically acceptable acid addition salts can conveniently be obtained by treating the base form with such appropriate acid in an anion form. Appropriate anions comprise, for example, acetate, benzenesulfonate , benzoate, bicarbonate, bitartrate, bromide, calcium edetate, camsyiate, carbonate, chloride, citrate, dihydrochloride, edetate, edisylate, estolate, esylate, fumarate, gluceptate, gluconate, glutamate, glycollylarsanilate, hexylresorcinate, hydrabamine, hydrobromide, hydrochloride, hydroxynaphthoate, iodide, isethionate, lactate, lactobionate, malate, maleate, mandelate, mesylate, methylbromide, methylnitrate, methylsulfate, mucate, napsylate, nitrate, pamoate (embonate), pantothenate, phosphate/diphosphate, polygalacturonate, salicylate, stearate, subacetate, succinate, sulfate, tannate, tartrate, teoclate, triethiodide, and the like. Conversely said salt forms can be converted by treatment with an appropriate base into the free base form. The compounds of formula (1) containing an acidic proton may also be converted into their nontoxic metal or amine addition salt forms by treatment with appropriate organic and inorganic bases in a cation form. Appropriate basic salts comprise those formed with organic cations such as benzathine, chloroprocaine, choline, diethanolamine, ethylenediamine, meglumine, procaine, and the like; and those formed with metallic cations such as aluminum, calcium, lithium, magnesium, potassium, sodium, zinc, and the like. Conversely said salt forms can be converted by treatment with an appropriate acid into the free form.

The "N-oxide" forms of the present compounds are meant to comprise those wherein one or several nitrogen atoms in any one of the triazole rings are oxidized (e.g., mono-or di-oxide). The nitrogen mono-oxides may exist as a single positional isomer or a mixture of positional isomers (e.g., a mixture of 1 -N-oxide, 2-N-oxide, and 4-N-oxide triazoles).

The term "quaternary amine" as used hereinbefore defines the quaternary ammonium salts which the compounds of formula (1) are able to form by reaction between a basic nitrogen of a compound of formula (1) and an appropriate quaternizing agent, such as, for example, an optionally substituted alkylhalide, arylhalide or arylalkylhalide, e.g. methyliodide or benzyliodide. Other reactants with good leaving groups may also be used, such as alkyl trifluoromethanesulfonates, alkyl methanesulfonates, and alkyl p-toluenesulfonates. A quaternary amine has a positively charged nitrogen. Pharmaceutically acceptable counterions include chloro, bromo, iodo, trifluoro acetate and acetate. The counterion of choice can be introduced using ion exchange resins. Quaternary amines of compounds of formula (1) may be obtained by alkylating a nitrogen-containing heterocycle, i.e. one or the two triazole rings, with bromoethyl acetate to give a quaternary ammonium mono- or disalt.

Some of the compounds of formula (1) may also exist in their tautomeric form. Such forms, although not explicitly indicated in the above formula, are intended to be included within the scope of the present invention.

According to another embodiment, the present invention relates to a method for making the compounds represented by the structural formula (1) wherein R' is as herein-above defined and wherein OY is a sterol residue. A preferred method usually proceeds in two steps. In a first step, a precursor being a sterol-containing carboxylic acid represented by the structural formula: HO - C(O) - R' - C(O) - OY is made by reacting a sterol represented by the structural formula YOH with a R' -containing dicarboxylic acid or dicarboxylic acid anhydride. In a second step, the precursor made in the first step (i.e. a sterol-containing carboxylic acid) being represented by the structural formula:

HO - C(O) - R' - C(O) - OY or an activated form thereof, such as the corresponding carbonyl chloride, is reacted with fluconazole.

Suitable R' -containing dicarboxylic acids or dicarboxylic acid anhydrides for performing the first step of the method are well known to the skilled person, and can be readily selected from commercially available reactants once the desired type (saturated or ethylenically unsaturated; linear or branched or cyclic; chain length) of divalent group R' has been defined. The following species are provided for illustration purpose only and are not limiting the scope of the present invention.

Suitable R' -containing dicarboxylic acid anhydrides for this method of the present invention may be selected from the group consisting of succinic anhydride, glutaric anhydride, adipic anhydride, maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, 1 ,2-cyclobutanedicarboxylic acid anhydride, cis-l,2-cyclo- pentanedicarboxylic acid anhydride, cis-l,3-cyclopentanedicarboxylic acid anhydride, 1,2- cyclohexanedicarboxylic acid anhydride, l-cyclopentene-l,2-dicarboxylic acid anhydride and 1 ,2-cycloheptane-dicarboxylic acid anhydride.

Suitable R'-containing dicarboxylic acids for this method of the present invention may be selected from the group consisting of mesaconic acid, 1,4-cyclohexanedicarboxylic acid, 1,4- cycloheptanedicarboxylic acid, 1,5-cyclo-octanedicarboxylic acid, cis-1,2- cyclopentanedicarboxylic acid, trans- 1 ,2-cyclopentanedicarboxylic acid, cis-1,3- cyclopentanedicarboxylic acid and cis-l,2-cyclobutanedicarboxylic acid.

The reaction conditions, e.g. temperature, duration, molar ratio between the reactants, generally suitable for each synthetic step are well known to the skilled person. If necessary for optimisation of the reaction yield, the second reaction step (esterification of a carboxylic acid) may be performed in the presence of an effective amount of an esterification catalyst. Several classes of suitable esterification catalysts are well known to the skilled person. Alternatively, the second reaction step may be facilitated by first activating the carboxylic acid group of the precursor into a carbonyl chloride, e.g. by means of sulfonyl chloride at elevated temperature (from about 40⁰C to about 100⁰C) in the presence of a suitable solvent. An illustrative embodiment of the production method of the present invention, wherein Y is a cholesterol and n is 2, is schematically shown in Scheme 1 of Example 1.

The resulting compounds may be optionally converted into a pharmaceutically acceptable salt or vice versa according to the methods known by the skilled in the art.

Further, compounds of formula (1) may be converted into each other following art-known functional group transformation reactions. For example, amino groups may be N-alkylated, nitro groups reduced to amino groups, a halo atom may be exchanged for another halo.

Pure stereo chemically isomeric forms of the compounds of formula (1) may be obtained by the application of art-known procedures. Diastereomers may be separated by physical methods such as selective crystallization and chromatographic techniques, e.g., counter-current distribution, liquid chromatography and the like.

The compounds of formula (1) may be obtained as racemic mixtures of enantiomers, which can be separated from one another following art-known resolution procedures. The racemic compounds of formula (1) that are sufficiently basic or acidic may be converted into the corresponding diastereomeric salt forms by reaction with a suitable chiral acid, respectively chiral base. Said diastereomeric salt forms are subsequently separated, for example, by selective or fractional crystallization and the enantiomers are liberated therefrom by alkali or acid. An alternative manner of separating the enantiomeric forms of the compounds of formula (1) involves liquid chromatography, in particular liquid chromatography using a chiral stationary phase. Said pure stereo chemically isomeric forms may also be derived from the corresponding pure stereo chemically isomeric forms of the appropriate starting materials, provided that the reaction occurs stereospecifϊcally. Preferably if a specific stereoisomer is desired, said compound may be synthesized by stereospecific methods of preparation. These methods may advantageously employ enantiomerically pure starting materials.

In another aspect the present invention relates to pharmaceutical compositions comprising a therapeutically effective amount of a compound according to any of the embodiments referred herein, and one or more pharmaceutically acceptable excipients.

The pharmaceutical compositions according to this invention may be administered orally or in any other suitable fashion. In case of oral administration, the pharmaceutical composition may take the form of a tablet, aqueous dispersion, dispersable powder or granule, emulsion, hard or soft capsule, syrup, elixir or gel. The dosing forms may be prepared using any method known in the art for manufacturing these pharmaceutical compositions and may comprise as additives sweeteners, flavoring agents, coloring agents, preservatives and the like. Carrier materials and excipients are detailed hereinbelow and may include, inter alia, calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents, binding agents and the like. The pharmaceutical compositions of this invention may be included in a gelatin capsule mixed with any inert solid diluent or carrier material, or has the form of a soft gelatin capsule, in which the ingredient is mixed with a water or oil medium. Aqueous dispersions may comprise the biologically active composition in combination with a suspending agent, dispersing agent or wetting agent. Oil dispersions may comprise suspending agents such as a vegetable oil. Rectal administration is also applicable to the pharmaceutical compositions of this invention, for instance in the form of suppositories or gels.

Due to the modified water-solubility characteristics of thecompounds of the present invention under physiological conditions, injection (e.g. intramuscularly, intravenously, subcutaneously, intraperitoneally, intra-articularly, intralesionally, intraventricularly, by spinal injection, by intraosseous infusion, or transdermally) is also applicable as a mode of administration for veterinary and pharmaceutical applications, for instance in the form of injectable aqueous solutions, dispersions, emulsions or suspensions (e.g. microemulsions, micro-suspensions or nanosuspensions), depending upon the disorder to be treated and the condition of the patient. Examples of aqueous solutions include, for example, water, saline, phosphate buffered saline, Hank's solution, Ringer's solution, dextrose/saline, glucose solutions and the like. The pharmaceutical injectable compositions may contain one or more pharmaceutically acceptable auxiliary substances as required to approximate physiological conditions or to improve stability, appearance or ease of administration, such as buffering agents, tonicity adjusting agents, wetting agents, detergents and the like. Additives can also include additional active ingredients such as bactericidal agents, or stabilising agents. For example, the aqueous solution of the invention may contain one or more additives selected from the group consisting of sodium acetate, sodium lactate, sodium chloride, potassium chloride, calcium chloride, sorbitan monolaurate and triethanolamine oleate. These aqueous compositions can be sterilised by conventional, well- known sterilisation techniques, or can be sterile filtered. The resulting aqueous solutions can be packaged for use as such, or can be lyophilised, the lyophilised preparation being combined with a sterile aqueous solution prior to administration. Such aqueous solutions are appropriate for injection and, in particular, for intravenous injection. Intravenous injection is a particularly appropriate means of delivery for using certain compounds of this invention. The intravenous solution can include detergents and emulsifiers such as lipids. Aqueous solutions also are useful for oral and enteral and other routes of administration as tonics, and for administration to mucous or other membranes as, e.g., nose or eye drops. The aqueous composition of this invention may contain the compound in an amount from about 1 mg/ml to about 100 mg/ml, preferably from about 5 to 20 mg/ml.

The term "pharmaceutically acceptable carrier or excipient" as used herein in relation to any type of pharmaceutical or veterinary compositions means any material or substance with which the active principle, i.e. the compound of this invention, may be formulated in order to facilitate its application or dissemination to the locus to be treated, for instance by dissolving, dispersing or diffusing the said composition, and/or to facilitate its storage, transport or handling without impairing its effectiveness. The pharmaceutically acceptable carrier may be a solid or a liquid or a gas which has been compressed to form a liquid, i.e. the compositions of this invention can suitably be used as concentrates, emulsions, solutions, granulates, dusts, sprays, aerosols, pellets or powders.

Suitable pharmaceutical carriers for use in the said pharmaceutical compositions and their formulation are well known to those skilled in the art. There is no particular restriction to their selection within the present invention although special attention may be paid to the selection of suitable carrier combinations that can assist in properly formulating the compound in view of the expected time release profile. Suitable pharmaceutical carriers include additives such as wetting agents, dispersing agents, stickers, adhesives, emulsifying or surface-active agents, thickening agents, complexing agents, gelling agents, solvents, coatings, antibacterial and antifungal agents (for example phenol, sorbic acid, chlorobutanol), isotonic agents (such as sugars or sodium chloride) and the like, provided the same are consistent with pharmaceutical practice, i.e. carriers and additives which do not create permanent damage to mammals.

The pharmaceutical compositions of the present invention may be prepared in any known manner, for instance by homogeneously mixing, dissolving, spray-drying, coating and/or grinding the active ingredients, in a one-step or a multi-steps procedure, with the selected carrier material and, where appropriate, the other additives such as surface-active agents. The compositions may also be prepared by micronisation, for instance in view to obtain them in the form of microspheres usually having a diameter of about 1 to 10 μm, namely for the manufacture of microcapsules for controlled or sustained release of the biologically active agent. Suitable surface-active agents to be used in the pharmaceutical compositions of the present invention are non-ionic, cationic and/or anionic surfactants having good emulsifying, dispersing and/or wetting properties. Suitable anionic surfactants include both water-soluble soaps and water-soluble synthetic surface-active agents. Suitable soaps are alkaline or alkaline-earth metal salts, unsubstituted or substituted ammonium salts of higher fatty acids (C₁₀-C₂₂), e.g. the sodium or potassium salts of oleic or stearic acid, or of natural fatty acid mixtures obtainable form coconut oil or tallow oil. Synthetic surfactants include sodium or calcium salts of polyacrylic acids; fatty sulphonates and sulphates; sulphonated benzimidazole derivatives and alkylarylsulphonates. Fatty sulphonates or sulphates are usually in the form of alkaline or alkaline-earth metal salts, unsubstituted ammonium salts or ammonium salts substituted with an alkyl or acyl radical having from 8 to 22 carbon atoms, e.g. the sodium or calcium salt of lignosulphonic acid or dodecylsulphonic acid or a mixture of fatty alcohol sulphates obtained from natural fatty acids, alkaline or alkaline-earth metal salts of sulphuric or sulphonic acid esters (such as sodium lauryl sulphate) and sulphonic acids of fatty alcohol/ethylene oxide adducts. Suitable sulphonated benzimidazole derivatives preferably contain 8 to 22 carbon atoms. Examples of alkylarylsulphonates are the sodium, calcium or alcanolamine salts of dodecylbenzene sulphonic acid or dibutyl-naphthalenesulphonic acid or a naphtalene-sulphonic acid/formaldehyde condensation product. Also suitable are the corresponding phosphates, e.g. salts of phosphoric acid ester and an adduct of p-nonylphenol with ethylene and/or propylene oxide, or phospholipids. Suitable phospholipids for this purpose are the natural (originating from animal or plant cells) or synthetic phospholipids of the cephalin or lecithin type such as e.g. phosphatidylethanolamine, phosphatidylserine, phosphatidylglycerine, lysolecithin, cardiolipin, dioctanyl-phosphatidylcholine, dipalmitoylphoshatidylcholine and their mixtures.

Suitable non-ionic surfactants include polyethoxylated and poly-propoxylated derivatives of alkylphenols, fatty alcohols, fatty acids, aliphatic amines or amides containing at least 12 carbon atoms in the molecule, alkylarenesulphonates and dialkylsulphosuccinates, such as polyglycol ether derivatives of aliphatic and cycloaliphatic alcohols, saturated and unsaturated fatty acids and alkylphenols, said derivatives preferably containing 3 to 10 glycol ether groups and 8 to 20 carbon atoms in the (aliphatic) hydrocarbon moiety and 6 to 18 carbon atoms in the alkyl moiety of the alkylphenol. Further suitable non-ionic surfactants are water-soluble adducts of polyethylene oxide with poylypropylene glycol, ethylenediamino -polypropylene glycol containing 1 to 10 carbon atoms in the alkyl chain, which adducts contain 20 to 250 ethyleneglycol ether groups and/or 10 to 100 propyleneglycol ether groups. Such compounds usually contain from 1 to 5 ethyleneglycol units per propyleneglycol unit. Representative examples of non-ionic surfactants are nonylphenol-polyethoxyethanol, castor oil polyglycolic ethers, poly-propylene/po Iy ethylene oxide adducts, tributylphenoxy-polyethoxyethanol, polyethyleneglycol and octylphenoxypolyethoxyethanol. Fatty acid esters of polyethylene sorbitan (such as polyoxy ethylene sorbitan trioleate), glycerol, sorbitan, sucrose and pentaerythritol are also suitable non-ionic surfactants.

Suitable cationic surfactants include quaternary ammonium salts, preferably halides, having four hydrocarbon radicals optionally substituted with halo, phenyl, substituted phenyl or hydroxy; for instance quaternary ammonium salts containing as N-substituent(s) at least one Cs-C₂₂ alkyl radical (e.g. cetyl, lauryl, palmityl, myristyl, oleyl and the like) and, as further substituents, unsubstituted or halogenated lower alkyl, benzyl and/or hydroxy-Ci_4 alkyl radicals.

A more detailed description of surface-active agents suitable for this purpose may be found for instance in "McCutcheon's Detergents and Emulsifiers Annual" (MC Publishing Crop., Ridgewood, New Jersey, 1981), "Tensid-Taschenbuch", 2^nd ed. (Hanser Verlag, Vienna, 1981) and "Encyclopaedia of Surfactants" (Chemical Publishing Co., New York, 1981).

Structure-forming, thickening or gel- forming agents may be included into the pharmaceutical compositions and combined preparations of the invention. Suitable such agents are in particular highly dispersed silicic acid, such as the product commercially available under the trade name Aerosil; bentonites; tetraalkyl ammonium salts of montmorillonites (e.g. products commercially available under the trade name Bentone), wherein each of the alkyl groups may contain from 1 to 20 carbon atoms; cetostearyl alcohol and modified castor oil products (e.g. the product commercially available under the trade name Antisettle).

Gelling agents which may be included into the pharmaceutical compositions of the present invention include, but are not limited to, cellulose derivatives such as carboxymethylcellulose, cellulose acetate and the like; natural gums such as arabic gum, xanthum gum, tragacanth gum, guar gum and the like; gelatin; silicon dioxide; synthetic polymers such as carbomers, and mixtures thereof. Gelatin and modified celluloses represent a preferred class of gelling agents.

Other optional excipients which may be included in the pharmaceutical compositions of the present invention include additives such as magnesium oxide; azo dyes; organic and inorganic pigments such as titanium dioxide; UV-absorbers; stabilisers; odor masking agents; viscosity enhancers; antioxidants such as, for example, ascorbyl palmitate, sodium bisulfite, sodium metabisulfite and the like, and mixtures thereof; preservatives such as, for example, potassium sorbate, sodium benzoate, sorbic acid, propyl gallate, benzylalcohol, methyl paraben, propyl paraben and the like; sequestering agents such as ethylene-diamine tetraacetic acid; flavoring agents such as natural vanillin; buffers such as citric acid and acetic acid; extenders or bulking agents such as silicates, diatomaceous earth, magnesium oxide or aluminum oxide; densifϊcation agents such as magnesium salts; and mixtures thereof.

Additional ingredients may be included in order to control the duration of action of the bio logically- active agent (phenol derivative) in the compositions of the invention. Control release compositions may thus be achieved by selecting appropriate polymer carriers such as for example polyesters, polyamino-acids, polyvinyl-pyrrolidone, ethylene-vinyl acetate copolymers, methylcellulose, carboxy-methylcellulose, protamine sulfate and the like. The rate of drug release and duration of action may also be controlled by incorporating the active agent into particles, e.g. microcapsules, of a polymeric substance such as hydrogels, polylactic acid, hydroxymethylcellulose, polymethylmethacrylate and the other above-described polymers. Such methods include colloid drug delivery systems like liposomes, microspheres, microemulsions, nanoparticles, nanocapsules and so on. Depending upon the route of administration, the pharmaceutical composition of this invention may also require protective coatings.

Pharmaceutical forms suitable for injectable use include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation thereof. Typical carriers for this purpose therefore include biocompatible aqueous buffers, ethanol, glycerol, propylene glycol, polyethylene glycol, maltodextrins, complexing agents such as cyclodextrins and the like, and mixtures thereof in any suitable proportions.

In one embodiment, the invention relates to a pharmaceutical composition being in the form of a suspension of the compound of the invention in one or more pharmaceutically acceptable solvents selected from the group consisting of polyethylene glycols with a molecular weight from 200 to 1,000, hydro xypropyl-β-cyclodextrin, fatty carboxylic acid triglycerides, and condensates of ethylene oxide with hydrogenated castor oil.

Other modes of local drug administration can also be used. For example, the selected active agent may be administered topically, in an ointment, gel or the like, or transdermally, using a conventional transdermal drug delivery system.

The compounds of the present invention are useful because they possess pharmacological activity in animals, including humans. In particular, the compounds are useful in the treatment or prevention of fungal infections, including yeast infections. For example, they are useful in treating topical fungal infections in man caused by, among other organisms, species of Candida, Trichophyton, Microsporum or Epiderrnophyton, or in mucosal infections caused by Candida albicans (e.g. thrush and vaginal candidiasis). They can also be used in the treatment of systemic fungal infections caused by, for example, species of Candida (e.g. Candida albicans), Cryptococcus neofonnans, Aspergillus flavus, Aspergillus fumigatus, Coccididides, Paracoccidiodes, Histoplasma, or Blastomyces.

Furthermore, the compounds of the present invention may be used to treat mycotic peritonitis among deep-seated mycosis agents, in addition to the following diseases for which fluconazole is indicated: fungemia, respiratory tract mycosis, digestive tract mycosis, urinary tract mycosis, mycotic meningitis, cryptococcal meningitis, onychomycosis, cryptococcosis, coccidiomycosis, and the like.

The compounds of the present invention may also be used as a prophylactic agent of candidiasis in immunocompromised patients, such as those patients with hematologic cancers, organ transplants, AIDS, or in elder or pediatric populations.

The compounds of the present invention, pharmaceutically acceptable salts thereof, or any subgroup thereof may therefore be used as a medicament. Said use as a medicament or method of treatment comprises the systemic administration to infected subjects or to subjects susceptible to fungal infections, including yeasts, of an amount effective to combat the conditions associated with the fungal infection, in particular Candida infection.

The present invention also relates to the use of the present compounds, pharmaceutically acceptable salts thereof, or any subgroup thereof for the manufacture of a medicament for the prevention or treatment of fungal infections. In other words, the present invention further relates to the compound of formula (1), pharmaceutically acceptable salts thereof, or any subgroup thereof, for use as an antifungal agent.

In one embodiment, the invention relates to a compound according to any one of the embodiments presented herein, for use as a therapeutic agent against candidiasis, onychomycosis, cryptococcosis, cryptococcal meningitis, coccidiomycosis or histoplasmosis.

In another embodiment, the invention relates to a compound according to any one of the embodiments presented herein, for use as a prophylactic agent of candidiasis in immunocompromised patients, such as patients with hematologic cancers or solid organ transplants).

The present invention furthermore relates to a method of prevention or treatment of fungal infections, said method comprising the administration of an effective amount of a compound of formula (1), a pharmaceutically acceptable salt thereof, or of a compound of any of the subgroups of compounds of formula (1), as specified herein, to a patient in need of such prevention or treatment.

In a further aspect, the present invention relates to the use of the chemical group of formula (2) as a promo iety

(2) wherein R and OY are each as defined in any one of the embodiments herein; and the wavy line (depicted by */wv^) indicates the bond to the tertiary alcohol residue of a drug.

This promoiety is valuable in designing further prodrugs for other pharmaceutical compounds, not necessarily related to fluconazole. Examples of drugs that can be derivatized into prodrugs with the promoeity of formula (2) include, without being limited to, voriconazole (2R,3S)-2- (2,4-difiuorophenyl)-3-fiuoro-4-pyrimidinyl)- 1 -( 1 H- 1 ,2,4-triazol- 1 -yl)-butan-2-ol, tramadol, meprotixol (9-(3-dimethylaminopropyl)-2-methoxy-thioxanthen-9-ol), clofedanol (l-(2- chlorophenyl)-3-dimethylamino-l-phenyl-propan-l-ol), and clobutinol (l-(4-chlorophenyl)-4- dimethy 1- amino -2 , 3 -dimethy l-butan-2-o 1) .

The term "promoiety" refers to a chemical group, i.e. moiety, bonded to a drug, typically to a functional group of the drug, via bond(s) that are cleavable under specified conditions of use. The bond(s) between the drug and promoiety may be cleaved by enzymatic or non-enzymatic means. Under the conditions of use, for example following administration to a patient, the bond(s) between the drug and promoiety may be cleaved to release the parent drug. Cleavage of the promoiety may proceed spontaneously, such as via a hydrolysis reaction, or may be catalyzed or induced by another agent, such as by an enzyme, by light, by acid, or by a change of or exposure to a physical or environmental parameter such as a change of temperature, pH, etc. The agent may be endogenous to the conditions of use, such as an enzyme present in the systemic circulation of a patient to which the prodrug is administered or the acidic conditions of the stomach, or the agent may be supplied exogenously.

In addition, the present invention relates to a method of extending the release of fluconazole, which comprises converting fluconazole into a compound of formula (1), a pharmaceutically acceptable salt thereof, or any subgroup thereof.

The following examples are only given by way of illustration of the above described general principles of the present invention.

Examples

Example 1 - Production and characterisation of a fluconazole derivative represented by the structural formula (1) This example illustrates the production of a fluconazole derivative of the present invention being represented by the structural formula (1), wherein OY is a cholesterol residue and wherein R' is (CH2)2, as schematically shown below in Scheme 1.

Scheme 1

chotestefol I£ g j79%)

5-1

5-2 SfiSCOOOa - Rueonazote Parent dnijj

SSS κ-3 (4?^!

On top of the scheme, a cholesterol-containing carboxylic acid precursor noted as 5-1 was first made by reacting cholesterol with succinic anhydride at reflux of dichloromethane in the presence of 4-dimethylaminopyridine (DMAP) acting as a nucleophilic catalyst. The reaction yield of this first step was 79%. Then the resulting cholesterol-containing carboxylic acid precursor 5-1 was activated into the corresponding carbonyl chloride noted as 5-2 by means of sulfonyl chloride at 65°C in toluene as a solvent. In the next step, the cholesterol-containing carbonyl chloride 5-2 was reacted with fluconazole in the presence of sodium hydride in a solvent mixture comprising toluene and dimethylformamide, at a temperature between 0⁰C and about 20⁰C. The reaction yield of this last step was 47%.

The resulting fluconazole derivative, i.e. 2-(2,4-difluorophenyl)-l,3-di(lH-l,2,4-triazol-l- yl)propan-2-yl (3S,8S,9S, 1 OR, 13R, 14S, 17R)- 10, 13-dimethyl- 17-((R)-6-methylheptan-2-yl)- 2,3,4,7,8,9,10,11,12,13, 14,15, 16,17-tetradecahydro-lH-cyclopenta[α]phenanthren-3-yl succinate, was structurally characterised by proton nuclear magnetic resonance and mass spectrometry as follows:

- ¹H NMR (400 MHz, DMSO-de): peaks at 8.06 (s), 7.87 (s), 7.05 (m), 6.91 (m), 6.87 (m), 5.36 (m), 5.17, 5.05, 4.64 (m), 2.66 (m), 2.60 (m), 2.29 (m), 1.99 (m), 1.84 (m), 1.57-0.94 (m), 1.01 (s), 0.91 (d), 0.87 and 0.85 (dd), and 0.67 (s) ppm; and

- MS: 775 (M+H).

Example 2 - Solubility of fluconazole derivative in pharmaceutical solvents

Table 1 provides the solubility data at 25°C, expressed in mg/ml, of the final fluconazole derivative produced and characterised in Example 1. The solubility determination method used was as follows: a suspension of 6 mg of the relevant fluconazole derivative in 500 μl of the relevant pharmaceutical solvent was rotatively shaken for 24 hours at 800 rpm at 25°C. The saturated fluconazole derivative solution was filtered (0.45 μm) and 150 μl of the filtrate was diluted in dimethylsulfoxide (50 μl DMSO). This solution was assayed, each assay being carried out in three-fold, by measurement with Liquid Chromatography-Mass Spectrometry (LCMS, lμl and 10 μl injection). Standards were prepared by dissolving the relevant fluconazole derivative in DMSO (1 mg/ml). To determine the solubility, four aliquots (0.5, 1, 2, 4 μl) of the standared solution were injected using the same LCMS conditions as for the above exemplary samples.

Table 1

Pharmaceutical solvent Example 1

H₂O (pH = 2) 0.0

H₂O (pH = 7) 0.0

H₂O (pH = 10) 0.0

H₂O/hydroxypropyl-β-cyclodextrin (60/40) 0.5

H₂O/Vitamin E TPGS NF (90/10) 1.7

H₂O/Cremophor RH 40 ^a (80/20) 0.1

H₂O/polysorbate 80 (80/20) 0.1

Polyethylene glycol MW 400 1.3

Miglyol 812 ^b O₁O

^a an emulsifying agent obtained by reacting 45 moles of ethylene oxide with 1 mole of hydrogenated castor oil, commercially available from BASF AG (Germany). b a caprylic/capric acid triglyceride, commercially available from SASOL GmbH (Germany). Example 3 - Chemical stability of a fluconazole derivative represented by the structural formula (1) in pharmaceutical solvents

Table 2 provides the chemical stability data in some pharmaceutical solvent at 25°C, expressed as the weight percentage (% w/w) of the final fluconazole derivative produced and characterised in Example 1 that remained in solution after a certain period of time. The test was carried out twice, and the remaining weight % was determined by Liquid Chromatography-Mass Spectrometry (LCMS).

Table 2

4 hours 1 day 2 days 7 days 14 days

Pharmaceutical solvents

H₂O (pH = 2) 100.0 98.7 99.4 98.6 99.2

H₂O (pH = 7) 100.0 99.7 98.3 98.9 99.6

H₂O (pH = 10) 87.4 88.1 88.1 88.2 88.6

H₂O/hydroxypropyl-β-cyclodextrin (60/40) 99.8 99.7 100.0 100.0 100.0

Polyethyleneglycol 400 100.0 100.0 100.0 100.0 100.0

Table 2 shows that, except in water at pH 10, at most 1% of the fluconazole derivative did not remain in the relevant aqueous or organic solution after 14 days.

Claims

1. A compound represented by the structural formula (1):

(1) and the salts, N-oxides, quaternary amines, and stereoisomers thereof, wherein:

R' is a saturated or ethylenically unsaturated linear or branched alkylene group having from 2 to 4 carbon atoms or a saturated or ethylenically unsaturated cycloalkylene group having from 4 to 8 carbon atoms, and

- OY is a sterol residue.

2. The compound according to claim 1, being represented by the structural formula (1) wherein said sterol residue OY is selected from the group consisting of zoosterol residue, phytosterol residue, ergosterol residue, cholesterol residue, cholestanol residue, campesterol residue, lanosterol residue, sitosterol residue, stigmasterol residue, and cycloartenol residue.

3. The compound according to any one of claims 1 to 2, being represented by the structural formula (1) wherein R' is (CH₂)_n and n is 2, 3 or 4; or R' is selected from the group consisting of - CH = CH - , - CH = C(CH₃) - , - CH - C(=CH₂) - , cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, cyclopentenylene, cyclohexenylene and phenylene.

4. A compound according to any one of claims 1 to 3 or a pharmaceutically acceptable salt thereof, for use as a medicament.

5. A compound according to any one of claims 1 to 3, for use as an antifungal agent.

6. A compound according to any one of claims 1 to 3, for use as a therapeutic agent against candidiasis, onychomycosis, cryptococcosis, cryptococcal meningitis, coccidiomycosis or histoplasmosis.

7. A compound according to any one of claims 1 to 3, for use as a prophylactic agent of candidiasis in immunocompromised patients.

8. A pharmaceutical composition comprising a therapeutically effective amount of a compound according to any one of claims 1 to 3, and one or more pharmaceutically acceptable excipients.

9. The pharmaceutical composition according to claim 8, being in the form of an injectable aqueous solution.

10. The pharmaceutical composition according to claim 8, wherein said pharmaceutical composition is administered intravenously, intramuscularly, subcutaneously, intraperitoneally, intra-articularly, intralesionally, intraventricularly, by spinal injection, by intraosseous infusion, or transdermally.

11. The pharmaceutical composition according to claim 8, being in the form of a suspension of the compound according to any one of claims 1 to 3 in one or more pharmaceutically acceptable solvents selected from the group consisting of polyethylene glycols with a molecular weight from 200 to 1,000, hydro xypropyl-β-cyclodextrin, fatty carboxylic acid triglycerides, and condensates of ethylene oxide with hydrogenated castor oil.

12. A method for producing a compound according to claim 1 and being represented by the structural formula (1), said method comprising the steps of :

(a) making a sterol-containing carboxylic acid precursor represented by the structural formula: HO - C(O) - R' - C(O) - OY by reacting a sterol represented by the structural formula YOH with an R'-containing dicarboxylic acid or dicarboxylic acid anhydride; and

(b) reacting said sterol-containing carboxylic acid precursor represented by the structural formula: HO - C(O) - R' - C(O) - OY with fluconazole.

13. The method according to claim 12, wherein the dicarboxylic acid anhydride used in step (a) is selected from the group consisting of succinic anhydride, glutaric anhydride, adipic anhydride, maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, 1 ,2-cyclobutanedicarboxylic acid anhydride, cis-l,2-cyclo- pentanedicarboxylic acid anhydride, cis-l,3-cyclopentanedicarboxylic acid anhydride, 1,2- cyclohexanedicarboxylic acid anhydride, l-cyclopentene-l,2-dicarboxylic acid anhydride and 1,2-cycloheptane-dicarboxylic acid anhydride.

14. The method according to claim 12, wherein the dicarboxylic acid used in step (a) is selected from the group consisting of 1,4-cyclo-hexanedicarboxylic acid, 1,4- cycloheptanedicarboxylic acid, 1,5-cyclo-octanedicarboxylic acid, cis-1,2- cyclopentanedicarboxylic acid, trans- 1 ,2-cyclopentanedicarboxylic acid, cis-1,3- cyclopentanedicarboxylic acid and cis-l,2-cyclobutanedicarboxylic acid.

15. Use of the chemical group of formula (2) as a promoiety

(2) wherein R and OY are each as defined in claim 1; and the wavy line (depicted by */wv^) indicates the bond to the tertiary alcohol residue of a drug.

16. A method of extending the release of fluconazole, which comprises converting fluconazole into a compound according to any one of claims 1 to 3 or a pharmaceutically acceptable salt thereof.

17. A method of prevention or treatment of fungal infections, which comprises administering an effective amount of a compound according to any one of claims 1 to 3, to a patient in need of such prevention or treatment.