WO1995028965A1

WO1995028965A1 - High solubility multicomponent inclusion complexes consisting of an acidic drug, a cyclodextrin and a base

Info

Publication number: WO1995028965A1
Application number: PCT/EP1995/001407
Authority: WO
Inventors: Paolo Chiesi; Paolo Ventura; Maurizio Del Canale; Maurizio Redenti; Daniela Acerbi; Massimo Pasini; Jösef SZEJTLI; Maria Vikmon; Eva Fenyvesi
Original assignee: Chiesi Farmaceutici S.P.A.
Priority date: 1994-04-22
Filing date: 1995-04-13
Publication date: 1995-11-02
Also published as: IL113450A0; ATE194777T1; ITMI940790A1; HK1013627A1; ZA953206B; DE69518070D1; CA2188388A1; ES2148512T3; PT756493E; ITMI940790A0; DE69518070T2; EP0756493A1; IL113450A; EP0756493B1; IT1269578B; US5773029A; AU2307695A

Abstract

Multicomponent inclusion complexes characterized by the presence of an acidic drug, a base and a cyclodextrin are disclosed. Said complexes have a specific solubility in water.

Description

HIGH SOLUBILITY MULTICOMPONENT INCLUSION COMPLEXE CONSISTING OF AN ACIDIC DRUG. A CYCLODEXTRIN AND A BASE

The invention relates to multicomponent inclusio complexes basically consisting of a drug bearing a acidic group (hereinafter defined as acidic drug), cyclodextrin and a base. In Italian Patent application n^β MI93 A 000141, three-component inclusion complexes consisting of basic-type drug, a cyclodextrin and an acid, characterized by a very high solubility in water, wer described. The drugs used in the formation of thes complexes, in the presence of the organic or inorgani acid which acts as a counter-ion, give rise t amphyphilic structures, i.e. characterized by strongly hydrophobic group and an hydrophilic polar head.

It is known that the molecules with such a structure have colloidal properties in aqueous solutions, i.e. they are capable of forming aggregates at suitable concentration and of lowering the surface 'tension of the solvent: in other words, they act as surfactants.

Among the classes of compounds which have mostl been studied from this aspect (Attwood D. , Florence A.T., Surfactant Systems, their chemistry, pharmacy an biology, Chapmam and Hall, UK, 1983) are the diphenylmethane derivatives and the tricycli derivatives, some of which (terfenadine, tamoxifen, cyclobenzaprine) turned out to be excellent agents fo the formation of the multicomponent complexes.

Therefore, it has been assumed that the high, unexpected increase in the solubility of th hydrophobic guest drug and of the cyclodextrin which i observed when the multicomponent complexes ar dissolved in water, is due to a reciprocal, synergisti effect of a component on the other: in other words, th cyclodextrin would increase the guest solubility b complexation, whereas the guest, once reached concentration in solution sufficient to give aggregates and/or micells would act as a surfactant towards the cyclodextrin.

The preparation processes, which consist i removing solvent from a supersaturated solution of the components, would favour such a mutual interaction.

Measurements of the relaxation time "spin-lattice" on the proton and "spin-spin" on the carbon carried out on the multicomponent complex terfenadine-tartaric acid-B-cyclodextrin confirmed that the drug guest is certainly aggregated in solution and therefore it is capable of acting as a surfactant.

Now it has surprisingly been observed that the aggregation also remains in the presence of cyclodextrins, contrary to what reported in literature. It is known, in fact, that cyclodextrins generally increase the critical micellar concentration (c.m.c.) this creating conditions unfavourable to micellation [Casu B., Grenni A., Naggi A. and Torri G. , In Proceedings of the Fourth International Symposium on Cyclodextrin, Eds. 0. Huber and J. Szejtli., Kluwer Academic Publishers, Dordrecht, 1988, pp. 189-195; Satake I., Ikenoue T. , Takeshita T. , Hayakawa K. an Maeda T., Bull. Chem. Soc. Jpn. , 58, 2746-2750 (1985)].

A number of examples of formation of complexe with cyclodextrins in the presence of conventiona surfactants are reported in literature [R. Palepu, J.E Richardson, V.C. Reinsborough: Langmuir 1989, 5, 218 221; G. Nelson, I.M. Warner: Carbohydr. Res. 1989, 192 305-312] and the formation of complexes o cyclodextrins with amphyphilic drugs was described b Takiwasa N. et al. in Colloid. Polym. Sci. 1993, 271(5 which characterized the ther odynamic propertie thereof.

Up to now, however, no examples are known usin the intrinsic surfactant properties of the include molecule to obtain very soluble complexes as far a both the included molecule and the cyclodextrin itsel are concerned.

This principle was verified by the Applicant als for acidic drugs having a potentially amphyphili structure.

Thus it has been found, and it is the object o the present invention, that also with acidic molecules, the simultaneous salt formation with suitable basi counter-ions and complexation with cyclodextrins, dramatically increases the aqueous solubility.

Usually, as for basic drugs addition salts wit organic or inorganic acids are prepared to enhanc solubility, analogously for acidic drugs salts wit organic or inorganic bases are used. The preparation of these salts, in order t increase solubility, in many cases only favours th preparation of the pharmaceutical formulation, withou involving a real advantage in terms of an enhance absorption.

In fact, it often happens that the dissociatio constant of the salt is higher than the pH of th medium in which the absorption takes place (mucosa cutis or plasma) whereby even administering the salt i the absorption site the drug is found in the form o the free acid. In the case of acidic drugs also the poo solubility and the subsequent reduced bioavailabilit can be improved by means of the complexation wit cyclodextrins.

In the prior art a lot of examples of acidic drug complexed with cyclodextrins with good results ar described.

Now it has surprisingly been found that . th formation of complexes of acidic drugs wit cyclodextrins (CD) in the presence of bases in se molar ratios gives rise to the formation of complexe easily soluble in water with very high concentration of both guest and host molecules.

The general method for the preparation of acidi drug:CD:base complexes is based on the usual principl of removing solvent from a supersaturated solution o the components, and it involves the following steps: a) suspension: suitable amounts of drug, cyclodextri and base in defined stoichiometric amounts ar suspended in distilled water or other suitabl solvent; b ) homogenization: the suspension is homogenized b stirring and/or sonication until obtaining an opalescent solution; c) filtration: the solution is filtered, with a suitable system, until obtaining a clear solution; d) drying: water or solvent is removed by conventional techniques such as freeze-drying, spray-drying, drying in oven and the like. With the same method, complexes with alfa or gamma CD, hydroxypropyl-BCD (HPBCD), dimethyl-BCD (DIMEB), RAMEB (Random Methylated B-cyclodextrin) or other cyclodextrin derivatives can be prepared to obtain, with the most soluble BCD derivatives, even more concentrated solutions with good stability characteristics which can give liquid pharmaceutical preparations for oral or parenteral use.

The basic component of the complexes according to the invention can be of both inorganic and organic nature.

Specific examples of bases comprise alkali or alkaline-earth hydroxides, secondary or tertiary amines, such as diethanolamine, triethanolamine, diethylamine, methylamine, tromethamine (TRIS) and the like.

By acidic drug any drug is meant having at least an acidic function such as a carboxy, sulfonic, sulfonylamino, sulfonylureic, phenol group and the like.

Examples of classes of acidic drugs comprise oxicams, hypoglycemic sulfonylureas, benzothiadiazine diuretics, barbituric acids, arylacetic and arylpropionic antiinflammatory acids. The molar ratios of the cyclodextrin or derivative can vary from 0.5 to 10 per mole of drug, whereas the molar ratios of the basic component can vary from 0.1 to 10 moles, per mole of drug. The invention is illustrated in detail by the following examples.

The examples relates to drugs belonging to different chemical and therapeutical classes, selected as particularly significant test molecules, based on their characteristics, to exemplify the invention.

However, the invention itself can obviously be applied to any other suitable acidic molecule. EXAMPLE 1

Preparation of glibenclamide-βCD-sodium hydroxide soluble complexes.

20 mmoles of sodium hydroxide are dissolved in 1 litre of distilled water. This solution is added with, in sequence, 60 mmoles of βCD and 20 mmoles of glibenclamide. with stirring. The suspensions are homogenized by strong stirring and sonicated until obtaining slightly opalescent solutions. The solutions are filtered through a sintered glass pre-filter. The solid complexes are obtained by freeze-drying the clear solution. The X ray diffraction pattern of the product shows a completely amorphous structure. EXAMPLE 2

Preparation of glibencla ide-βCD-diethanolamine complexes.

1 mmole of glibenclamide and 2 mmoles of βCD are suspended in 60 ml of distilled water. Then the suspension is added with 1 to 4 mmoles of diethanolamine and sonicated for some minutes. The resulting clear or slightly opalescent solutions are filtered through a syntered glass pre-filter. The resulting solutions are freeze-dried. EXAMPLE 3

Preparation of other glibenclamide-βCD-organic bases complexes.

With a process analogous to the one of the above examples, the following complexes were prepared: 3a) glibenclamide (1 mmole) -βCD (1 mmole) triethanolamine (2 mmoles) in a 1:1:2 ratio; 3b) glibenclamide (1 mmole) -βCD (1 mmole) diethylamine (2 mmoles) in a 1:1:2 ratio; 3c) glibenclamide (1 mmole) -βCD (1 mmole) triethylamine (2 mmoles) in a 1:1:2 ratio;

3d-e-f) glibenclamide-βCD-triethanolamine (or diethy¬ lamine or triethylamine) in a 1:2:2 ratio; 3g) glibenclamide (1 mmole) -βCD (1 mmole) - TRIS (7 mmoles) in a 1:1:7 ratio; 3h) glibenclamide (1 mmole) -βCD (2 mmoles) -

TRIS (7 mmoles) in a 1:2:7 ratio. EXAMPLE 4

Preparation of piroxicam-DIMEB-sodium hydroxide complexes. 50 mmoles of piroxicam and 100 mmoles of DIMEB are suspended in 420 ml of distilled water. 50 ml of a IN sodium hydroxide solution are added with continuous stirring. The resulting solution is filtered and the complex is separated by freeze-drying. EXAMPLE 5

Preparation of piroxicam-|fCD-inorganic bases complexes. 6 mmoles of piroxicam and 12 mmoles of CD are suspended in 100 ml of distilled water. 8 ml of a IN sodium hydroxide (or potassium or ammonium) solution are added with stirring. The solution is neutralized until a fine precipitate of the complex is obtained (pH 8-10).

The complex is separated by filtration and dehydrated in oven at 40-50"C. With a similar process, the complex piroxicam-βCD-sodium hydroxide in a 1:1:1 ratio was prepared. EXAMPLE 6 Preparation of piroxicam-HPβCD-NaOH complexes.

10 mmoles of piroxicam and 10 or 20 mmoles of HPβCD (substitution degree 4.2) are suspended in 100 ml of distilled water. 10 ml of a IN NaOH solution are added with stirring . The resulting solution is filtered and the complexes are separated by freeze- drying. EXAMPLE 7 Preparation of other complexes of piroxicam with cyclodextrins and organic bases. With a process analogous to the one of example 6, the following complexes were prepared: piroxica -βCD-diethanolamine in a 1:2:1 and 1:2:2 ratio; piroxicam- fCD-diethanolamine in a 1:2:1 and 1:2:2 ratio. EXAMPLE 8

Preparation of chlorotiazide-cyclodextrin-organic base complexes.

With a process analogous to the one of the above examples, the following complexes were prepared: chlorothiazide- CD-lγsine in a 1:1:2 and 1:2: ratio; chlorothiazide-HPβCD-lysine in a 1:1:2 and 1:2: ratio; chlorothiazide-βCD-lysine in a 1:1:2 and 1:2: ratio; chlorothiazide-βCD-diethanolamine in a 1:1: ratio; - chlorothiazide-HPβCD-diethanolamine in a 1:1:1

1:1:2, 1:2:1 and 1:2:2 ratio; chlorothiazide- cD-diethanolamine in a 1:1:2 an

1:2:2 ratio; * chlorothiazide-HPβCD-ethanolamine in a 1:2:1 an 1:2:2 ratio; chlorothiazide-HPβCD-triethanolamine in a 1:1:2

1:2:1 and 1:2:2.

The most significant solubility data of som complexes of the invention are reported in Tables 1 5, in which they are compared with those of th starting compounds and of other systems. EXAMPLE 9

Preparation of ibuprofen/βCD/triethanolamine 1:1: complex. With a process analogous to the one of the abov examples, a complex with 0.21 g (1.0 mM) of ibuprofen 1.1 g (1.0 mM) of βCD and 0.15 g (1.0 mM) o triethanolamine was prepared.

The water solubility of ibuprofen was 9 mg/ml. EXAMPLE 10

Preparation of indometacin/βCD/triethanolamin 1:2:2 complex.

With a process analogous to the one of the abov examples, a complex with 0.24 g (0.64 mM) o indometacin, 1.53 g (1.17 mM) of βCD and 0.20 g (0.6 mM) of triethanolamine was prepared.

The water solubility of indometacin was 7.2 mg/ml. EXAMPLE 11

Preparation of furosemide/βCD/diethanolamine 1:2: complex. With a process analogous to the one of the abov examples, a complex with 0.22 g (0.64 mM) o furosemide, 1.53 g (1.17 mM) of βCD and 0.13 g (0.6 mM) of diethanolamine was prepared.

The water solubility of furosemide was 7.8 mg/ml.

Table 1: Equilibrium solubility, at room temperature at different pH values, of Glibenclamide (G), it sodium salt (G-Na), and a physical mixture thereof wit βCD (G/βCD) in a 1:1, 1:2, 1:3.

pH Solubility tag/al]

G G-Na σ/βco

1:1 1:2 1:3

4.0 0.004

7.39 0.0188 0

7.5 0.020

8.35 5.04

8.47 4.64

8.53 3.49

8.89 0.299

9.0 0.600 s

> 9.3 7.0

9.53 0.768

pKa of Glibenclamide: 6.8.

Table 2: Instant solubility, at room temperature, a various times, at different pH values, o multicomponent Glibencla ide/βCD/Diethanolamin (G/βCD/DEtOH) and Glibenclamide/βCD/NaOH (G/βCD/NaOH complexes.

pH time Solubility -»g/al) [min]

G/βCD/DEtOH G/βCD/NaOH

1:2:3 1:2:4 1:1:1 | 1:2:1 1:3:1

1.4 15 0.10 0.10

20-30 0.10 0.10

40 0.110

5.38 10 0.17

5.61 10 0.24 0.24

6.50 10 1.16 1.16

7.03 10 0.82

7.3 15 21.5

7.8 60 42.5

9.1 05 33

9.29 60 9.6

Table 3: Glibenclamide concentrations versus tim obtained by dissolution at room temperature in pH = and pH = 1,4 buffer of Glibenclamide (G), a physica mixture thereof with βCD (G/βCD) and multicomponen Glibenclamide/βCD/NaOH) (G/βCD/NaOH) complexes.

pi time Solubility l»g/«l_ [mln] G/βCD/NaOH G/βCD/NaOH G/βCD G 1:2:1 1:3:1 1:2

5.0 05 0.61 < 0.01 < 0.01

10 0.81 < 0.01 < 0.01

20 0.36 < 0.01 < 0.01

40 0.23 < 0.01 < 0.01

50 0.27 < 0.01 < 0.01

1.4 05 0.110 < 0.01

15 0.114 < 0.01

30 0.110 < 0.01

40 0.110 < 0.01

50 0.080 < 0.01

Table 4: Equilibrium solubility (eq.) and instant solubility at various times, at room temperature, at different pH values, respectively of Piroxicam (P) and multicomponent Piroxicam/RAMEB/NaOH (P/RAMEB/NaOH) and Piroxicam/HPβCD/NaOH (P/HPβCD/NaOH) complexes.

note: Piroxicam pKa is 6.3; the solubility of multicomponent complexes was evaluated both at a pH lower than pKa and at pH values higher than pKa.

Table 5: Chlorothiazide concentrations obtained b dissolution at room temperature in water of a Chlorothiazide/HPBCD physical mixture, Chlorothiazide/cosolubilizer and multicomponent Chlorothiazide/HPβCD/cosolubilizer systems.

System molar Solubility ratio [ g/ml

C/HPβCD/lysine multicomponent 1 :2 : 1 60

C/lysine physical mixture 1:1 1.25

C/HPβCD physical mixture 1:2 0.34

C/HPβCD/triethanolamine multicomponent 1:2:2 125

G/triethanolamine physical mixture 1:2 2.9

C/HPβCD physical mixture 1:2 0.34

note: Chlorothiazide has an equilibrium solubility, at room temperature, varying as a function of pH, from 0.4 to 0.7 mg/ml about, and at pKa of 6.7 and 9.5.

In Table 1 and 4 the equilibrium solubility of some drugs used for the preparation of the complexes of the invention was determined, since for the compounds as such the respective sodium salts and the physical mixture with βCD the maximum solubility conditions are obtained at equilibrium.

On the contrary, in the case of the complex, (as in Tables 2 and 4), the instant solubility is determined, since in most cases to define the maximum solubility of a complex, also the supersaturation solubility appearing in a set time interval (which varies depending on the complex and is indicated in the Table every time) immediately after the dissolution.

The Tables also evidence that the complexes of the invention attain a remarkable increase in solubility, compared with the starting compounds.

This increase in solubility cannot be ascribed only to the complexation of the drug, since it also occurs at pH values at which no ionization of the cyclodextrin hydroxyls is observed.

The water solubilities of acidic drugs and of β- cyclodextrin in some complexes of the invention are represented in Table 6.

Table 6

Complex guest solubility host (βCD)solubility in water [mg/ml] in water [mg/ml]

Glibenclamide/βCD/NaOH 1:3:1 5.04 34.7

Ibuprofen/βCD/Triethanolamine 1:1:1 9.0 49.5 ^

Indumetacin/βCD/Triethanolamine 1:2:2 7.2 46.0

Furosemide/βCD/Diethanolamine 1:2:2 7.8 53.5

From the data reported in the Table 6 t remarkable solubility enhancement of β-cyclodextrin m be observed.

Infact the inherent aqueous solubility of cyclodextrin is 18.5 mg/ml.

Moreover we verified whether the increase solubility of the active ingredient of the complexes the invention act favourably also on the respecti absorption characteristics. The product resulting from complexation glibenclamide with βCD and sodium hydroxide was us for these tests. Glibenclamide is a well-known dru widely used in the treatment of non insulin-depende diabetes mellitus. It belongs to the sulfonylure chemical class, which is the most important group antidiabetics active orally.

The first pharmaceutical formulations glibenclamide gave rise to variable and incomple absorption. The active ingredient content of su formulations in conventional tablets was 5 mg f unitary dose.

Subsequent studies allowed to obtain a nov formulation with improved bioavailability, in which t compound is present micronized in an amount of 3.5 for unitary dose.

The pharmacokinetic and pharmacodynamic paramete of this novel formulation in tablets are equivalent those of the conventional formulation.

The inventors compared the absorption rate, t bioavailability and the pharmacodynamic profile of t product obtained by complexation of glibenclamide wi βCD and sodium hydroxide (glibenclamide content 3.5 mg) with the best commercial formulation of glibenclamide (Euglucon N 3.5 mg) . EXAMPLE 12 The study was carried out on 6 healthy volunteers which were administered with a single dose of the compounds under test, according to a randomized cross scheme.

Each individual received, in the fasting state, in each of the two test period, separated by a 7 day wash¬ out interval, a tablet containing the complex of the invention or the reference compound (glibenclamide content of both: 3.5 mg) together with a bolus of 40 g of glucose. 30 minutes later, a second bolus of 50 g of glucose was administered. At different times and up to 12 hours after the administration of the compounds, the plasma concentrations of glibenclamide, insulin and glucose were evaluated.

Table 7 shows the main pharmacokinetic parameters related to glibenclamide determined on the basis of the individual plasma concentrations.

20

The results show that after the administration of tablets containing the complex of the invention, a remarkably higher absorption rate than that of the reference formulation (about 3 times) is attained, whereas bioavailability, evaluated as the extent of absorption and proved by the AUCe value, is comparable. The data also evidenced for the complex of the invention a better pharmacodynamic activity profile, since a better control of the glycemic peaks was revealed following glucose intake and higher glycemic levels far from meals.

Claims

1. Multicomponent inclusion complexes containing an acidic drug, a base and a cyclodextrin characterized in that they are obtained by simultaneous salt formation and complexation.

2. Inclusion complexes according to claim 1, wherein the base is inorganic or organic.

3. Inclusion complexes according to claim 1, characterized in that cyclodextrin is a alfa, beta or gamma cyclodextrin.

4. Inclusion complexes according to claim 1, characterized in that the cyclodextrin is a beta- cyclodextrin derivative selected from hydroxypropyl- beta-cyclodextrin, dimethyl-beta-cyclodextrin or RAMEB.

5. Inclusion complexes according to claim 1, characterized in that, compared with the drug, cyclodextrin is present in molar ratios from 0.5 to 10 and the base in molar ratios from 0.1 to 10.

6. Complexes according to any one of claims 1-5, obtained by means of any one of the techniques conventionally used in the preparation of inclusion complexes.

7. Complexes acccording to any one of claims 1-5, wherein the cyclodextrin concentration is higher than its inherent aqueous solubility.

8. A process for the preparation of multicomponent inclusion complexes of the preceding claims comprising the following steps: a) suspension in water or other solvent of suitable quantities of drug, cyclodextrin and base; b) homogenization of the suspension obtained in step a) by stirring and/or sonication to obtain a clear or slightly opalescent solution; c) filtration of the solution obtained in step b) by using a suitable system to obtain a clear solution; d) drying of the solution obtained in step c).

9. Pharmaceutical compositions containing an inclusion complex of claim 1 in a therapeutically effective amount, in combination with one or more excipients.