ITMI980510A1 - PHARMACEUTICAL COMPOSITIONS CONTAINING COMPLEX INCLUSION WITH MELATONIN - Google Patents

Description

DESCRIPTION of the invention entitled:

"PHARMACEUTICAL COMPOSITIONS CONTAINING MELATONIN INCLUSION COMPLEXES"

Scope of the invention

Object of the present invention are pharmaceutical compositions containing melatonin inclusion complexes in a polymeric material. These compositions are particularly useful for the solubilization of melatonin in aqueous solvents.

Previous art

Melatonin, N-acetyl-5-methoxytryptamine, is a hormone secreted mainly by the pineal gland, responsible for numerous physiological responses in humans [Arendt J., Melatonin and the mammalian pineal gland, 42-207, 1995, Chapman & HallEd .]

There are numerous therapeutic influences for which melatonin is believed to be responsible. Among them that of synchronizer of biological rhythms and in particular of acting as a normalizer of the wake / sleep rhythm, of anti-fertility agent, of agent to slow down the aging processes and others. An important role of melatonin seems to be to regulate the secretion of growth hormone with the possibility of having a synergistic action in anticancer therapies that see more drugs established.

From a biochemical point of view, melatonin is known to be a powerful antioxidant and it has been hypothesized that it can protect DNA and cell replication processes from errors that generate mutations in the replication system, such as interactions with free radicals and with mutagens.

Melatonin is characterized by a low solubility in water (5.10-3 M) [Shida C., Journal of Pineal Research, 16: 198-201, 1994] and, when administered to humans orally, shows a low bioavailability ( about 30%) which is also characterized by a wide variability (10-56%) in the same subject, due both to hepatic metabolism phenomena, and to a variability of absorption according to the different conditions of intake and the characteristics of the subject treated .

[Wei-Li D., New England Journal of Medicine, 336: 1028-1029, 1997].

The need to improve the solubility of melatonin is therefore a felt problem and a direct approach to solving this problem is addressed in the European patent Fraschini F., EP 330625 which reports the use of an adenosine / melatonin mixture (in relation 4: 1) in order to solubilize melatonin itself. The solubility value obtained and the experimental conditions are however not reported in the patent. The solubility of this mixture was experimentally measured by us at 20 ° C, and it was found to be equal to 6.10 <-3> Moli / L, as reported in Example 3, or not very dissimilar from that of melatonin. which.

It has now been found, and it is the object of the present invention, that by forming inclusion complexes between melatonin and a suitable polymer (for example (3-cyciodextrin) it is instead possible to improve the solubility and bioavailability of melatonin itself following of its increased absorption.

Formations consisting of a polymeric material and an active ingredient in which the active ingredient is incorporated into the polymer are defined as inclusion complexes. The polymer helps to convey the drug in the aqueous medium by altering some of the characteristic physical properties of the active ingredient itself, so that, after the formation of the complex, the solubility of the active ingredient in aqueous solvents increases significantly.

Extensive references on the inclusion complexes can be found in Kirk Orthmer 3 Ed., 6: 179, 1979, where the different methods available for their preparation are also described, such as for example: comacination, lyophilization, spray-drying and granulation.

For the purposes of the present invention, the term inclusion complexes includes, in addition to the actual inclusion complexes, also those preparations in which the active ingredient is supported on a polymeric material that carries it and facilitates its dissolution.

Detailed description

The inclusion complexes forming part of the invention may comprise various polymeric materials such as: complexing agents soluble in water, hydrophilic linear polymers or swollen cross-linked polymers insoluble or slightly soluble in water. The complexes can be prepared using known preparation techniques by mixing the polymer with the active principle in varying ratios according to the final desired characteristics.

The materials of the active ingredient inclusion or support complexes that can be used for the realization of the present invention are:

water-soluble complexing agents such as for example: α-, β-, γcyclodextrins and their derivatives such as for example hydroxypropyl-β-cyclodextrin. In this class, β-cyclodextrin is the preferred agent for the inclusion of melatonin.

linear hydrophilic polymers such as polyvinylpyrrolidone (PVP), cellulose and derivatives. In this class, PVP is the preferred inclusion agent for melatonin.

insoluble or slightly soluble cross-linked polymers that swell in contact with water such as: cross-linked polyvinylpyrrolidone (PVP XL), cross-linked cyclodextrins, cross-linked carboxymethyl starch, dextrans. The preferred inclusion agent in this class is PVP XL.

As mentioned above, among the various inclusion complexes mentioned above, the β-cyclodextrins are particularly suitable for the solubilization of melatonin in water. Cyclodextrins are cyclic oligosaccharides in which the glucopyranoside units are joined by glucosidic bonds. The cyclodextrin molecules are characterized by having a hydrophilic external surface and an apolar internal central cavity. This allows non-polar molecules to penetrate the lipophilic cavity of the cyclodextrin forming an inclusion complex.

The use of cyclodextrin derivatives in combination with melatonin for transdermal use was described by Konsil J., Drug Dev. Ind. Pharm. , 21: 1377-1387, 1995. In this work, however, reference is made to hydroxypropyl-β-cyclodextrna only as an absorption promoter in association with propylene glycol in the preparation of transdermal systems. No teaching is provided by the author about the possibility of using inclusion complexes as product solubilization agents.

In general, in the complex formed according to the present invention, the melatonin and the vehicle are mixed in a molar ratio of 1: 1, however this ratio can be lower or higher depending on the peculiar characteristics of the chosen polymer and the dissolution profile that is appropriate. to take melatonin during administration. In practice, molar ratios varying between 1: 0.5 and 1:20 are used, preferably between 1: 1 and 1: 4.

The preparation techniques that can be used to make the inclusion complexes as defined in the present invention can be of multiple nature and are in any case part of the known art. Examples of such techniques are:

comacination, which is based on the intimate mixing by grinding of the active ingredient and the chosen inclusion vehicle. Dry co-milling is carried out with various types of mills (with rotating or vibrational balls, rotor or high-energy mills) or any other device suitable for grinding / micronization capable of leading to a partial or total amorphization of crystalline melatonin. The variant of this technique which uses high-energy mills for the preparation of the comadnate is particularly suitable for the formulations of the present invention as it allows to obtain a melatonin complex with very small particle size, typically less than 10 μm and preferably less than 5. μm. Obtaining these particles allows for further optimization of the solubility characteristics of the complex and of the active ingredient included.

lyophilization, according to which the active principle and the polymer are dissolved in a solvent, generally water. The solution is then frozen and the solvent removed by sublimation under vacuum, leaving the active principle incorporated in the polymer as a residue.

granulation, according to which melatonin dissolved in water at 50 ° C is mixed with the polymer in which it must be incorporated. After mixing, the water is removed by drying at 45 <°> C.

spray-drying, according to which melatonin and the polymer are both distributed in a suitable solvent. The suspension is nebulized in a stream of hot air so that the solvent evaporates leaving the inclusion complex as a residue.

the precipitation, according to which the complex is precipitated from an aqueous solution of cyclodextrin and melatonin. The solution is kept under hot stirring (about 50-60 ° C) and the complex formed after cooling is separated by filtration.

Pharmaceutical compositions

With the melatonin-cyclodextrin inclusion complex it is possible to obtain pharmaceutical compositions of various types for administration which can be oral, parenteral, rectal, nasal, ocular, vaginal or buccal.

These compositions find application in all those therapeutic areas in which mel atonine has been shown to have a biological activity. In particular, pharmaceutical forms containing the inclusion complex with melatonin are included in a daily dosage range from 0.1 to 100 mg and preferably between 1 and 10 mg.

Examples of usable pharmaceutical forms are: hard and soft gelatin capsules; tablets in their various types, such as: fast-dissolving, coated, coated, slow-release, gastro-resistant, lyophilized tablets; granulates; suppositories; solutions for various uses: nasal sprays, drops, syrups and the like.

For the preparation of these pharmaceutical forms, excipients and preparative methods are used which are normally known to the average skilled in the art and which are reported both in common technical manuals and in pharmacopoeias.

Areas of application and therapeutic advantages

The melatonin complex thus obtained and conveyed can be used in all the applications envisaged for this active ingredient such as, for example: prophylaxis and tumor therapy, treatment of AIDS, treatment of panic states, antispasmodic effects, mild hypnotic effects, myelotropic action, antimitotic action, modulating action of NK cell activity, maintenance of an efficient immunological response and regulation of circadian rhythms.

Some examples are provided below which have the sole purpose of better illustrating the invention in question by demonstrating its advantages and applicability, without however constituting a limitation thereof.

EXAMPLE 1

Preparation of the complex with cyclodextrins

A) By precipitation

A melatonin solution obtained by heating at 50 ° C 1 g of melatonin in 1 liter of water is added to a solution of 5.52 g of β-cyclodextrin in 500 ml of water to form a solution in molar ratio 1: 1. The solution obtained is kept under stirring for 24 hours at 25 ° C, then cooled to 4 ° C. The precipitated material is collected, filtered, and dried under vacuum.

B) By freeze-drying

A solution, obtained by gentle heating of a 1: 4 molar mixture consisting of 232 mg of melatonin and 5.13 g of β-cyclodextrin, is divided into plates with a diameter of 10 cm and is freeze-dried in a Brizio-Basi lyophilizer using a cycle having the following experimental conditions: Cooling: -35 ° C for 4 hours; Vacuum: 0.1-0.2 mBar; Freeze drying time: 24 hours. 5.2 g of complex are obtained. C) By hot stirring

A solution of melatonin and β-cyclodextrin in molar ratio 1: 2 is prepared in 1 liter of water. The mixture is heated at 50 ° C for 1 hour, then it is allowed to cool under stirring and evaporated slowly under vacuum to obtain the desired complex.

D) By dry co-milling

232 g of melatonin and 5130 g of β-cyclodextrin in molar ratio 1: 4, are mixed dry and transferred to a high-energy mill (Sweko - USA) for 4 hours. The grinding time can be lengthened or reduced depending on the desired degree of amorphization and the residual crystallinity to be obtained. At the end, the product is discharged and passed through a 5000 mesh sieve.

E) By granulation

In a high-speed mixer / granulator, 0.742 kg of melatonin and 32.77 kg of β-cyclodextrin are mixed in a 1: 8 molar ratio. First β-cyclodestin is introduced and then an alcoholic solution containing melatonin in a 10% concentration. It is mixed for 25 'and the granulate is discharged and dried under vacuum.

F) For spray-dry

5 liters of aqueous mixture consisting of 10 g of melatonin and 55.28 g of β-cyclodextrin in a 1: 1 molar ratio are heated to 50 ° C under stirring. The solution obtained is loaded into a NIRO-ATOMIZER (UK) spray dryer and the solvent is evaporated under the following operating conditions: Feed rate: 750 ml / h; Air temperature: 105 ° C; Air flow 100 m <3> h.

EXAMPLE 2

The inclusion compound obtained according to any of the techniques described in Example 1 was characterized with the following analytical techniques:

A) Differential thermal analysis (DSC)

The differential thermal analysis data are conducted with the Mettler TA 300 (DSC 20) device at a speed of 10 ° C / min. in nitrogen current, in the temperature range of 30-400 ° C. Figure 1 shows the most significant temperature range (40-200 ° C), the chromatograms of:

a) pure melatonin,

b) pure β-cyclodextrin

c) physical mixture melatonin β-cyclodextrin (molar ratio 1: 1) d) inclusion complex melatonin / β-cyclodextrin in molar ratio 1: 1.

From a comparison between the chromatograms, the disappearance in trace d) of the melatonin fusion peak, at about 118 <°> C, due to the formation of the inclusion complex, is evident.

B) IR spectroscopy

The IR spectra were made by suspending the compounds in vaseline oil using FTIR equipment Mod. 1600 (PERKIN-ELMER).

Figure 2 shows:

a) spectrum of pure melatonin,

b) spectrum of pure (3-cyclodextrin

c) superposition of the spectrum of the melatonin / β-cyclodextrin inclusion complex in the ratio 1: 1 (d), and of the spectrum of the physical mixture melatonin β-cyclodextrin (c2).

The modifications of the typical bands of melatonin in the inclusion complex are evident, in particular the absorption bands at 1200 cm <-1> and at 1600 cm <-1>.

EXAMPLE 3

Solubility in water

Samples of pure melatonin, of melatonin mixed with adenosine in a ratio of 1: 4 as indicated in the Fraschini F. patent, EP 330625 and of the melatonin / β-cyclodextrin inclusion complex prepared as described respectively by methods B and D in Example 1 , are placed in 50 ml of distilled water at 20 ° C in the presence of a bottom body. The suspensions are stirred in a shaking shaker and samples of the supernatant are taken which, after filtration through the Millipore membrane, are read on a VARIAN spectrophotometer at a wavelength of 276 nm. Table 1 shows 1 determined solubility values (moles / liter).

TABLE 1

Solubility at 20 ° C in distilled water

Solubility Sample (Moli / L) Melatonin 5.0 10 <-3>

Melatonin / adenosine mixture 1: 4 6.0 10 <-3>

Complex Example 1, method B 3.0 10 <-2>

Complex Example 1, method D 2.7 10 <-2>

The results show how the use of a melatonin / βcyclodextrin complex allows to obtain a melatonin solubility significantly higher than that obtainable using the melatonin / adenosine mixture described in patent EP 330625.

EXAMPLE 4

Preparation of capsules containing the inclusion complex

The melatonin / B-cyclodextrin complex prepared according to one of the methods described in Example 1, is mixed with spray-dry lactose and magnesium stearate for 12 minutes in a TURBULA mixer. At the end, the powder mixture is divided into format 3 capsules containing the equivalent of 2 mg of melatonin having the following composition: melatonin / β-cyclodextrin 15 mg, lactose spray-dry 83 mg, magnesium stearate 2 mg.

EXAMPLE 5

Preparation of tablets containing the inclusion complex

The compound of inclusion melatonin / β-cyclodextrin in the ratio 1: 4, prepared according to what is reported in Example 1 (method B), is mixed in a V-mixer with avicel, lactose, carboxyethyl starch and magnesium stearate. 5 kg of mixture are compressed with the direct compression technique at a weight of 200 mg / tablet in a RONCHI tablet press equipped with 8 mm round punches to obtain tablets having the following composition: melatonin / β-cyclodextrin 69 mg (equal to 3 mg of melatonin), lactose 69 mg, avicel 50 mg, carboxymethyl starch 10 mg, magnesium stearate 2 mg.

EXAMPLE 6

Preparation of a granular containing the inclusion complex The melatonin / β-cyclodextrin inclusion complex in the ratio 1: 4, prepared according to what reported in Example 1 (method B), is diluted with sorbitol and subsequently lemon flavoring and aspartame are added . The mixture thus obtained contains 260 mg of melatonin / B-cyclodextrin complex equal to 10 mg of melatonin and is divided into sachets of 3 grams each having the following composition: melatonin / β-cyclodextrin 260 mg, sorbitol 2695 mg, lemon flavor 30 mg, aspartame 15 mg.

EXAMPLE 7

Dissolution of tablets containing the inclusion complex

The dissolution property of the tablets prepared as described in Example 5, is compared with that of tablets prepared using the same excipients, but containing melatonin without β-cyclodextrin (β-CDX). The dissolution was carried out in 250 ml of 0, 1 N HCl at 37 ° C, stirring at 50 rpm, using the US Pharmacopoeia Apparatus 2 [USP 23 Ed., P. 1791, 1995]. The samples taken at the times indicated in the following Table 2 were analyzed with a UV spectrophotometer at a wavelength of 276 nm, to determine the percentage of melatonin released.

TABLE 2

The results shown in the Table show how the dissolution of melatonin from tablets made using the melatonin / β-cyclodextria complex is significantly faster than that of tablets having the same composition, but containing only non-complexed melatonin.

Claims (13)

CLAIMS 1. Pharmaceutical composition for the administration of melatonin, comprising a complex of inclusion of the melatonin in polyhymene materials. 2. Composition according to claim 1, characterized in that the polymeric materials forming the inclusion complex are included in the group consisting of: water-soluble complexing agents, hydrophilic linear polymers and water-insoluble swelling cross-linked polymers. 3. Composition according to claim 2, characterized in that the water-soluble complexing agents are selected from the group consisting of: a-, 3-, γ-cyclodextrins or their derivatives and sodium carboxymethylamine. 4. Composition according to claim 3, characterized in that the complexing agent is β-cyclodextrin. 5. Composition according to claim 2, characterized in that the hydrophilic linear polymers forming the inclusion complex are selected from the group consisting of polyvinylpyrrolidone (PVP), cellulose and their derivatives. 6. Composition according to claim 2 characterized in that the water-insoluble swelling polymers forming the inclusion complex are selected from the group consisting of: cross-linked polyvinylpyrrolidone (PVP XL), cross-linked cyclodextrins, cross-linked carboxymethyl starch and dextrans. 7. Composition according to the preceding claims characterized in that the melatonin and the polymeric materials in the inclusion complex are mixed in a molar ratio which can vary from 1: 0.5 to 1:20, preferably from 1: 1 to 1: 4. 8. Composition according to the preceding claims selected from the group consisting of: hard or soft gelatin capsules; tablets: fast-dissolving, coated, coated, slow-release, gastro-resistant or lyophilized; granulates; suppositories; solutions: nasal sprays, drops or syrups. 9. Composition according to the preceding claims for the oral administration of melatonin. 10. Process for the preparation of the inclusion complex defined by the preceding claims, selected from the group of techniques comprising: comacination, lyophilization, granulation, and spray-drying. 11. Process according to claim 10, characterized in that the co-milling of the ingredients that make up the inclusion complex is carried out in high-energy mills. 12. Use of the compositions according to the preceding claims for the therapeutic or preventive treatment of pathologies which require the administration of melatonin in mammals. 13. Use of the compositions according to claim 12 for the treatment of tumor pathologies, AIDS or for the regulation of circadian rhythms in mammals in need of such treatment.