Description

The present invention relates to a process for the preparation of controlled release tablets containing glucosamine.

Glucosamine is a natural product present in shells of shellfishes and in bones and bone marrow of animals.

The chemical name of the compound is 2-amino-2-deoxy-D-glucose corresponding to the following formula:

Glucosamine is an amino sugar precursor of the components of cartilage called glucosaminoglycans that stimulate the collagen production. Therefore glucosamine protects joints against the loss of cartilage so helping to restore normal joint functions.

The oral administration of glucosamine is commonly used for the treatment of osteoarthritis just for its properties of preventing cartilage degeneration.

Glucosamine is rapidly metabolized in gastro intestinal tract and therefore the controlled release of glucosamine presents several benefits such as the longer duration of therapeutic treatment, the reduction of plasma levels variation, the decrease of daily administrations and the reduction of potential side effects related to a peak of plasma concentration several times in a day.

Glucosamine is quite unstable in the presence of humidity as it can easily oxidize.

Different oral controlled release glucosamine formulations are known in the art.

US 2004/0234599 relates to controlled release compositions wherein glucosamine is dispersed in a controlled release matrix comprising at least a hydrosoluble cellulose polymer such as hydroxypropylmethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose. WO 2008/136016 relates to controlled release glucosamine formulations comprising a core with a polymeric hydrophylic matrix and a polymeric permeable pH- independent coating.

US 2010/0010101 relates to rapid-melt compositions containing a binder, a salivating agent, a diluent/bulking material, and an active ingredient such as glucosamine. This formulation rapidly melts upon the application of pressure by the tongue of the patient and is particularly useful to make rapid-melt tablets, chew tablets or flashbeads. Such compositions are intended to be used for an immediate release of the active ingredient.

WO 2010/028290 relates to chewable pharmaceutical compositions for the sustained release of active ingredients, such as glucosamine, comprising a primary sustained release agent, a wax-like agent and a bulking or spheronizing agent. There is still the need of a stable oral controlled release glucosamine composition able to assure a release for a period of about 12 hours.

We have now found that controlled release glucosamine tablets comprising a hydrophobic matrix are particularly stable and assure an effective release of glucosamine for 24 hours when the preparation of the tablet is made by dispersion of glucosamine in the hydrophobic matrix by treatment at a temperature of at least 40°C.

It is therefore object of the present invention a controlled release tablet comprising an effective amount of glucosamine, a salt or derivative thereof dispersed in a hydrophobic matrix characterized by the fact that the dispersion of glucosamine, a salt or a derivative thereof in the hydrophobic matrix is carried out by treatment at a temperature of at least 40°C.

Glucosamine is used as free base glucosamine, glucosamine hydrochloride, glucosamine sulphate 2KCI, N-acetyl-glucosamine. Glucosamine sulphate 2KCI is preferably used.

Glucosamine can be optionally used in combination with other active ingredients such as ascorbic acid, vitamin A, vitamin E and chondroitin.

The amount of glucosamine is generally comprised from 30% to 80% by weight with respect to the final weight of the tablet, more preferably from 50% to 70% by weight. Any not thermolabile hydrophobic matrix can be used for the controlled release tablets according to the present invention. Examples of such matrices are waxes, fatty acids or derivatives thereof, such as carnauba wax, beeswax, stearic acid, magnesium stearate, adipic acid, oleic acid, glyceryl palmito stearate and glyceryl behenate.

Matrices made of fatty acids and derivatives thereof, more preferably made of stearic acid or derivatives thereof are preferably used. A matrix made of stearic acid and magnesium stearate is particularly preferred.

Stearic acid is preferably used in an amount from 20% to 40% by weight with respect to the weight of the tablet, more preferably from 25% to 30% by weight with respect to the weight of the tablet.

Magnesium stearate is preferably used in an amount from 2% to 8% by weight with respect to the weight of the tablet, more preferably from 4% to 6% by weight with respect to the weight of the tablet.

The tablet may be optionally coated with a cellulose based film or any other polymer or polymer mixture conventionally used for tablet's film coating.

When film coated, the tablet prepared according to the present invention is preferably coated with a cellulose based film such as for example Opadry Colorcon. The tablet can contain, in addition to the hydrophobic matrix, also other excipients normally used in the preparation of tablets such as diluents, binders, disgregants, glidants, non sticking agents, flavouring agents, colouring agents, etc.

The tablets according to the present invention preferably contain only the hydrophobic matrix and optionally a film coating.

The characteristic feature of the tablets of the present invention is represented by their preparation process which comprises the dispersion of glucosamine in the hydrophobic matrix by treatment at a temperature higher than about 40°C.

It is therefore a further object of the present invention a process for the preparation of controlled release tablets comprising glucosamine, a salt or derivative thereof and a hydrophobic matrix comprising the dispersion of glucosamine, a salt or derivative thereof in the hydrophobic matrix by treatment at a temperature higher than about 40°C.

The tablet according to the present invention can then be prepared using melting, blending, dry or wet granulation techniques carried out at a temperature higher than about 40°C.

The melting in oven of the mixture of glucosamine and hydrophobic matrix is preferably used. After the treatment at a temperature higher than about 40°C, the resultant mixture is compressed and optionally coated according to conventional techniques.

The upper limit in the range of the operative temperature for the preparation process of the tablets according to the present invention will be chosen depending on the type of process used and according to the thermal stability of tablet's components. It is evident that the temperature cannot be higher than 100°C in case of use of aqueous processes, while it can be higher in case of use of dry processes.

However, for practical and economical reasons it is preferred to make the dispersion of glucosamine in the hydrophobic matrix at a temperature between 40°C and 100°C.

The tablets prepared according to the present invention release effectively and constantly glucosamine for a period of about 12 hours as shown in fig.1 .

Furthermore the tablets show a high stability. Their appearance remains unchanged after their storage at 40°C and 75% of relative humidity for six months and more. In order to better illustrate the present invention without however limiting it the following examples are now given.

Preparation of tablets comprising glucosamine (750 mg), stearic acid (300 mg) and magnesium stearate (50 mg).

EXAMPLE 1

Preparation by melting in the oven

Glucosamine sulphate 2KCI, stearic acid and 50% magnesium stearate were blended in a cube blender for 10 minutes. The blended powder was loaded in a oven and warmed up at 80°C for about 2 hours. The melted product was cooled down at room temperature and then sieved in an oscillating granulator in order to reduce the particle size of the granules. The granulate was blended with the remaining magnesium stearate in a cube blender and compressed in capsule shaped tablets weighing 1 100 mg.

EXAMPLE 2

Preparation by granulation with water

Glucosamine sulphate 2KCI, stearic acid and 50% magnesium stearate were blended in a high share blender for 1 minute. Then boiling water was added and blended at high speed for 10 minutes. The granulate was uploaded from the high share blender to a fluid bed granulator for drying. The remaining magnesium stearate was added to the granulate by blending in a cube blender. The resultant mixture was compressed in capsule shaped tablets weighing 1 100 mg.

EXAMPLE 3

Preparation by hot granulation

Glucosamine sulphate 2KCI, stearic acid and 50% magnesium stearate were blended in a high share mixer. The mixture was warmed up at 80°C for 15 minutes maintaining the maximum speed of agitation. The melted product was cooled down at room temperature under gentle stirring and then sieved with an oscillating granulator in order to reduce the particle size of the granules. The granulate was blended with the remaining magnesium stearate in a cube blender and compressed in capsule shaped tablets weighing 1 100 mg.

EXAMPLE 4

Preparation by granulation with water

Glucosamine sulphate 2KCI, stearic acid and 50% magnesium stearate were blended in a high share mixer. The mixture was warmed up at 80°C for 15 minutes maintaining the maximum speed of agitation and then boiling water was added always maintaining the same agitation speed. The mixture was dried under vacuum for about 1 hour. The melted product was cooled down at room temperature and the granulate was sieved with an oscillating granulator in order to reduce the particle size of the granules. The granulate was blended with the remaining magnesium stearate in a cube blender and compressed in capsule shaped tablets weighing 1 100 mg.

Preparation of tablets comprising glucosamine (750 mg), stearic acid (300 mg), magnesium stearate (50 mg) and ascorbic acid (12 mg).

EXAMPLE 5

Preparation by melting in the oven

Glucosamine sulphate 2KCI, stearic acid, ascorbic acid and 50% magnesium stearate were blended in a cube blender for 10 minutes. The blended powder was loaded in a oven and warmed up at 80°C for about 2 hours. The melted product was cooled down at room temperature and then sieved in an oscillating granulator in order to reduce the particle size of the granules. The granulate was blended with the remaining magnesium stearate in a cube blender and compressed in capsule shaped tablets weighing 1 1 12 mg. EXAMPLE 6

Preparation by hot granulation

Glucosamine sulphate 2KCI, stearic acid and 50% magnesium stearate were blended in a high share mixer. The mixture was warmed up at 45°C for 15 minutes maintaining the maximum speed of agitation. The melted product was cooled down at room temperature under gentle stirring and then sieved with an oscillating granulator in order to reduce the particle size of the granules. The granulate was blended with the remaining magnesium stearate in a cube blender and compressed in capsule shaped tablets weighing 1 100 mg.

EXAMPLE 7

Preparation by granulation with water

Glucosamine sulphate 2KCI, stearic acid and 50% magnesium stearate were blended in a high share mixer. The mixture was warmed up at 45°C for 15 minutes maintaining the maximum speed of agitation and then boiling water was added always maintaining the same agitation speed. The mixture was dried under vacuum for about 1 hour. The melted product was cooled down at room temperature and the granulate was sieved with an oscillating granulator in order to reduce the particle size of the granules. The granulate was blended with the remaining magnesium stearate in a cube blender and compressed in capsule shaped tablets weighing 1 100 mg.