Patent Application
20060062845
1. Field of Invention
This invention relates to a tablet with controlled release of alfuzosin hydrochloride and to methods for synthesizing and administering the same.
2. Description of Related Art
Alfuzosin is a quinazolin derivative for oral administration (in the form of the hydrochloride) that selectively blocks postsynaptic alpha-1-receptors. In vitro studies have confirmed selectivity of the substance on alpha-1-receptors in the trigone of the urine bladder, urethra and prostate, but also to the sympathomimetic nerve impulse, which by stimulating the post-synaptic alpha receptors increases the tension of the smooth muscles of the lower urinary tract thus contributing to the resistance to outflow of urine. Clinical evidence of uroselectivity has been demonstrated. In men, alfuzosin improves voiding parameters and facilitates bladder emptying.
After administration of an immediate-release tablet containing alfuzosin hydrochloride, the active agent is rapidly and well absorbed. Bioavailability is 64% (45-90%). Peak plasma concentrations are reached within 1 hour after administration. The kinetic profile is characterized by large (sevenfold) inter-individual fluctuations in plasma concentrations. Terminal elimination half-life is approximately 5 h (1-10 h).
Thus, alfuzosin has a relatively short half-life, and is more intensely absorbed at the duodenum-jejunum level than in subsequent portions of the gastrointestinal tract. Consequently, for an optimum effect, the administration of alfuzosin hydrochloride as conventional tablets (with rapid disintegration and dissolution) must be carried out several times a day. Therapy with immediate release alfuzosin tablets typically requires a daily dose of 3 tablets containing 2.5 mg alfuzosin hydrochloride. For these reasons, alfuzosin hydrochloride is a candidate for the production of a pharmaceutical preparation with controlled release in the promixal upper parts of the tract (duodenum and jejunum).
U.S. Pat. No. 6,149,940 to Maggi et al. discloses such a pharmaceutical preparation, wherein alfuzosin hydrochloride ((R,S)-N-(3-(4-amino-6,7-dimethoxy-2-quinazolinyl) methylamino)propyl)tetrahydro-2-furancarboxamide hydrochloride) is provided in multilayered tablet further comprising a hydrophilic swelling agent, such as crosslinked polyvinylpyrrolidone (a.k.a. povidone or PVP), hydroxypropylcellulose or hydroxypropylmethylcellulose (a.k.a., hypromellose or HPMC) having a molecular weight from 1,000 to 100,000, crosslinked sodium carboxymethylcellulose, carboxymethyl starch or its salts, or divinylbenzene/potassium methyacrylate copolymer. The swelling agent swells upon contact with gastricjuices, such that the pharmaceutical preparation increases considerably in volume, which slows the passage of the pharmaceutical preparation through the stomach. In this way, most of the alfuzosin hydrochloride contained may be absorbed in a controlled manner in that portion of the gastrointestinal tract that has the highest capacity for absorption.
XATRAL LP (UROXATRAL in the U.S.) is a three-layered tablet prepared in accordance with the teachings of Maggi et al., wherein the active alfuzosin hydrochloride layer is sandwiched between two external swelling layers containing HPMC. These 10 mg sustained-release tablets can be administered once a day to achieve clinically relevant tissue concentrations. Moreover, the bioavailability of the 10 mg sustained-release tablets is 104% when compared to 2.5 mg immediate-release tablets. Peak plasma concentrations occur approximately 6-9 h after oral administration of the sustained-release formulation. The elimination half-life is approximately 9.1 h after oral doses.
The pharmacokinetic profile of the sustained-release formulation permits the higher initial daily dose. Therapeutically effective alfuzosin concentrations can be reached rapidly without excessive plasma levels. More uniform plasma levels are provided with minimal peak-to-trough fluctuation. This improved absorption profile minimizes the risk for undesirable effects.
Despite the foregoing developments, it is desired to provide alternative means for prolonged release of alfuzosin. It is still further desired to provide a monolithic tablet for prolonged release of alfuzosin. It is still further desired to provide a monolithic tablet for prolonged release of alfuzosin, which is bioequivalent with UROXATRAL, XATRAL LP 10 mg and/or XATRAL OD. It is also desired to provide a process for producing sustained-release tablets containing alfuzosin, which is less complex than the process employed to provide multilayered alfuzosin tablets.
All references cited herein are incorporated herein by reference in their entireties.
Accordingly, the invention provides a composition comprising:
In certain embodiments, the alfuzosin is alfuzosin hydrochloride.
In certain embodiments, the composition is a tablet free of layers.
In certain embodiments, the alfuzosin is homogeneously distributed throughout the composition.
In certain embodiments, the polymeric matrix is homogeneously distributed throughout the composition.
In certain embodiments, the polymeric matrix predominantly comprises a hydrophilic polymer adapted to gel or swell upon contact with gastrointestinal fluids.
In certain embodiments, the hydrophilic polymer is hydroxypropylmethylcellulose.
In certain embodiments, the composition further comprises lactose monohydrate, polyvinylpyrrolidone and magnesium stearate.
In certain embodiments, the composition comprises 1-30 mg alfuzosin hydrochloride, 2-100 mg lactose monohydrate, 20-800 mg hydroxypropylmethylcellulose, 2-100 mg polyvinylpyrrolidone and 0.1-25 mg magnesium stearate.
In certain embodiments, the composition comprises about 10 mg alfuzosin hydrochloride, about 7.8 mg lactose monohydrate, about 255 mg hydroxypropylmethylcellulose, about 24 mg polyvinylpyrrolidone and about 3.0 mg magnesium stearate.
In certain embodiments, the composition is adapted to induce a peak plasma concentration of alfuzosin about 6 hours to about 9 hours after oral administration.
In certain embodiments, an elimination half-life of the composition is about 9 hours after oral administration.
Also provided is a unit dosage form comprising a heterogeneous mixture of alfuzosin hydrochloride, lactose monohydrate, hydroxypropylmethylcellulose, polyvinylpyrrolidone and magnesium stearate, wherein the heterogeneous mixture is heterogeneously distributed throughout the unit dosage form.
In certain embodiments, the unit dosage form comprises 1-30 mg alfuzosin hydrochloride, 2-100 mg lactose monohydrate, 20-800 mg hydroxypropylmethylcellulose, 2-100 mg polyvinylpyrrolidone and 0.1-25 mg magnesium stearate.
In certain embodiments, the unit dosage form comprises about 10 mg alfuzosin hydrochloride, about 7.8 mg lactose monohydrate, about 255 mg hydroxypropylmethylcellulose, about 24 mg polyvinylpyrrolidone and about 3.0 mg magnesium stearate.
In certain embodiments, the unit dosage form is adapted to release 13-33% of the alfuzosin within 2 hours of administration, 40-60% of the alfuzosin within 7 hours of administration and greater than 80% of the alfuzosin within 20 hours of administration.
In certain embodiments, the unit dosage form is a monolithic tablet.
In certain embodiments, the unit dosage form has a pharmaceutically inactive external coating.
Further provided is a process for preparing the composition and/or unit dosage form of the invention, said process comprising:
In certain embodiments, the hydrophilic polymer is hydroxypropylmethylcellulose and the alfuzosin is alfuzosin hydrochloride.
In certain embodiments, the granulating comprises adding a granulation liquid to the blend and wet granulating the blend.
In certain embodiments, the blend comprises hydroxypropylmethylcellulose, alfuzosin hydrochloride and lactose monohydrate, the granulation liquid comprises polyvinylpyrrolidone and water and the lubricant comprises magnesium stearate.
In certain embodiments, the tablet contains 1-30 mg alfuzosin hydrochloride, 2-100 mg lactose monohydrate, 20-800 mg hydroxypropylmethylcellulose, 2-100 mg polyvinylpyrrolidone and 0.1-25 mg magnesium stearate.
In certain embodiments, the tablet contains about 10 mg alfuzosin hydrochloride, about 7.8 mg lactose monohydrate, about 255 mg hydroxypropylmethylcellulose, about 24 mg polyvinylpyrrolidone and about 3.0 mg magnesium stearate.
Still further provided is a method of treating benign prostatic hyperplasia, said method comprising administering to a patient a composition or unit dosage form of the invention once a day.
The invention will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein:
The invention provides a monolithic composition containing a mixture of an active agent and a retarding agent. The composition is preferably provided in the form of a tablet.
The term “monolithic” as used in expressions such as “monolithic tablet” is intended to denote that the tablet (or other object) is not layered. The term “monolithic” is not intended to require that the tablet be formed from a single material or comprise a completely homogenous mixture.
The active agent is preferably alfuzosin or a salt thereof, and is most preferably alfuzosin hydrochloride. The amount of active agent in the composition can be determined with routine experimentation using the present disclosure as a guide. When the active agent is alfuzosin hydrochloride, each dosage unit of the composition preferably contains from 1 mg to 250 mg, preferably 1 mg to 30 mg, most preferably about 10 mg (i.e., 10 mg±1 mg) alfuzosin hydrochloride.
Alfuzosin hydrochloride used for the manufacture of the inventive composition is freely soluble in water. To ensure that the active agent is gradually released, a highly viscous matrix is provided by the retarding agent. Preferably, the alfuzosin hydrochloride is released at rates substantially identical to the release rates of UROXATRAL, XATRAL LP 10 mg and/or XATRAL OD. In certain embodiments, the in vitro release rate profile is as follows: 2 h: 13-33 % released; 7 h: 40-60 % released; and 20 h:≧80% released. In certain embodiments, the composition is adapted to induce a peak plasma concentration of alfuzosin about 6 hours to about 9 hours after oral administration (to a patient) and/or the elimination half-life of the composition is about 9 hours (i.e., 9 hours±1 hour) after oral administration.
The retarding agent is a hydrophilic polymer that gels or swells upon contact with gastrointestinal fluids, such that passage of the formulation from the stomach (duodenum, jejunum, etc.) is delayed. In addition, the retarding agent provides a matrix from which the active agent cannot readily escape. Upon contact with water, alfuzosin hydrochloride dissolves and diffuses into the polymeric matrix. Thus, the release kinetic of the alfuzosin hydrochloride is governed by the relative magnitude of the rate of polymer swelling and erosion, which starts at the tablet surface and expands into the interior of the tablet with time.
Suitable hydrophilic polymers for use as the retarding agent are biocompatible. They are slowly soluble and/or slowly gelable and/or swell rapidly or at a different rate in aqueous liquids and then may optionally be broken down. Preferred polymers include hydroxymethylcellulose, hydroxyethyl-cellulose, hydroxypropylmethylcellulose having a molecular weight of from 1000 to 4,000,000, hydroxypropylcellulose having a molecular weight of from 2000 to 2,000,000, carboxyvinyl polymers, chitosans, mannans, galactomannans, xanthans, carrageenans, amylose, alginic acid, its salts and its derivatives, pectins, acrylates, methacrylates, acrylic/methacrylic copolymers, polyanhydrides, polyamino acids, poly(methyl vinyl ether/maleic anhydride) polymers, polyvinyl alcohols, glucans, scleroglucans, carboxymethylcellulose and its derivatives, ethylcellulose, methylcellulose and, in general, hydrophilic cellulose derivatives.
HPMC is the most preferred retarding agent, as it is pharmaceutically acceptable and non-ionic, such that no interactions between the polymer and other constituents are to be expected. HPMC provides a hydrophilic matrix in which the active agent is distributed uniformly, and is released over a sustained period of time.
The various HPMC quality grades commercially available differ in their molecular weight. The molecular weight of the polymer used and its concentration in the tablet are of particular importance for the release of the drug substance. Adjustment of these parameters to achieve desired results is possible with routine experimentation using the present disclosure as a guide. A higher molecular weight leads to an increase in gel strength and increased viscosity, reducing the release of the drug substance due to a greater barrier to diffusion and slower erosion of the tablet. Increasing the polymer concentration in the preparation, i.e., the ratio HPMC/drug substance, results in an increase of gel viscosity on the surface of the tablets. This delays the release of drug substance from the gel layer. The concentration effect is, however, of limited relevance for HPMC grades of high molecular weight.
The content of hydrophilic polymers may range from 5 to 90% relative to the total weight of the composition, but preferably from 80 to 90% and more preferably about 85%.
The composition can also include additives additional to the active agent and the retarding agent.
In certain embodiments, the composition can include wetting agents that are capable of facilitating interaction between the components of the composition and the biological fluids with which the composition comes into contact. Suitable wetting agents include but are not limited to anionic, cationic and nonionic surfactants. More specific non-limiting examples include sodium lauryl sulphate, sodium ricinoleate, sodium tetradecyl sulphate, sodium dioctyl sulphosuccinate, cetomagrogol, poloxamer, glyceryl monostearate, polysorbates, sorbitan monolaurate, lecithins or any other pharmaceutically acceptable surfactant.
In addition, other hydration-modifying additives may be used, such as, e.g., hydrophilic diluents such as mannitol, lactose, starches of various origins, sorbitol, xylitol, microcrystalline cellulose and/or substances which, in general, promote the penetration of water or of aqueous fluids into the pharmaceutical preparation, hydrophobic diluents such as glyceryl monostearate, palmitates, hydrogenated or unhydrogenated plant oils such as hydrogenated castor oil, waxes, mono-, di- or trisubstituted glycerides, for slowing down the penetration of water or of aqueous fluids into the pharmaceutical preparation.
The preparation of the composition, particularly the process of tableting, may introduce into the composition: lubricants such as magnesium stearate, stearic acid, glyceryl monostearate; polyoxyethylene glycols having a molecular weight of from 400 to 7,000,000; hydrogenated castor oil; glyceryl behenate; mono-, di- or trisubstituted glycerides; flow agents such as colloidal silica or any other silica; binders (e.g., povidone); buffers; absorbing agents; and other pharmaceutically acceptable additives.
In a particularly preferred embodiment, the composition of the invention comprises a tablet containing alfuzosin hydrochloride as the active ingredient, HPMC as the retarding agent, povidone as a binder, lactose monohydrate as a filler and magnesium stearate as a lubricant. Preferred ranges of these ingredients are listed in Table 1.
During development of the tablets of the invention, various types of manufacturing processes were investigated. First attempts were made to manufacture the tablets by direct compression after blending the drug substance with suitable excipients. The results revealed that direct compression is most practical with a formulation containing 10 to 50% HPMC. Above this percentage, the flowability of the dry mix decreases, resulting in unacceptable weight variation. Since higher concentrations of HPMC are preferred, direct compression is not the preferred means for tableting.
Granulation is preferred prior to the tableting to obtain a formulation of consistent quality containing a higher amount of HPMC and good flowing properties. Granulation tends to produce tablets having better friability than tablets produced by direct compression. Wet granulation, fluid bed granulation or dry compaction/granulation are all suitable granulation techniques, with wet granulation being most preferred.
Thus, a preferred tableting process comprises: mixing HPMC, alfuzosin hydrochloride and lactose monohydrate in a high shear mixer to form a blend; granulating the blend (preferably by adding a granulation liquid such as a solution of povidone in purified water); drying the granules on a dryer; sizing the dried granules; mixing the sized granules with magnesium stearate to obtain a mixture; and compressing the mixture (e.g., on an rotary press) to obtain tablets (e.g., flat and plain tablets having a diameter of about 8.0 mm). The blend shows no sticking, capping or insufficient hardness. The achievable hardness and friability are acceptable using this method.
Purified water is the most preferred solvent for the granulation liquid (or binder solution). However, alcohol and water/alcohol solvent blends are also suitable for use in the invention. The granulation liquid preferably contains a binder, which is most preferably povidone. Most preferably, povidone K25 is dissolved in water under continuous stirring to produce a lump-free granulation liquid.
The granules obtained from the wet granulation are dried until the desired loss on drying value (e.g., about 1% to about 5%) is achieved. Preferred drying conditions are a drying temperature of about 40° C. to about 80° C., more preferably about 80° C., and a drying time of about 4 hours to about 8 hours, more preferably about 6 hours at 40° C.
The dried granules are sized by passage through a sieve preferably of 12-40 mesh. A 20 mesh sieve is most preferred.
The sized granules are mixed with a lubricant prior to being pressed into tablets. The most preferred lubricant is magnesium stearate. The granules and lubricant are preferably mixed to homogeneity. In certain embodiments, mixing is conducted for about 1 to about 60 minutes, and preferably about 10 minutes.
The mixture of granules and lubricant is compressed into tablets, preferably using a rotary tablet machine. In certain embodiments, about 5,000 to about 300,000 tablets are produced per hour with a hardness of about 20N to about 300N. The shape of the tablets is not particularly limited. In certain embodiments, the tablets are flat and plain and have a diameter of about 8.0 mm.
To investigate the influence of the particle sizes of alufozosin hydrochloride and additives, the particle size distribution was determined by sieve analysis. Differences in particle size distribution exist between alfuzosin hydrochloride, HPMC and lactose monohydrate. The mixing step prior to granulation and the wet granulation process do not compensate for these differences. This could lead to separation in the hopper or the feed frame of the tablet press.
Therefore, it is preferred to include a grinding step in the process of producing the composition of the invention to reduce the particle size of the alfuzosin hydrochloride. The coarse material is preferably ground into small particles of less than about 0.25 mm diameter prior to being combined with the other ingredients.
The preferred particle size specification for alfuzosin hydrochloride is as follows:
The invention will be illustrated in more detail with reference to the following Examples, but it should be understood that the present invention is not deemed to be limited thereto.
The objective of the Examples is to demonstrate that a composition of the invention achieves sustained-release of alfuzosin hydrochloride, resulting in alfuzosin plasma concentration profiles corresponding to those of the product marketed outside the U.S. under the trade name XATRAL LP 10 mg (“the reference formulation”). The reference formulation is a triple-layer tablet with alfuzosin hydrochloride provided in the middle layer. The upper and lower layers contain the swelling polymer HPMC.
A dissolution test with adequate discriminatory power was developed to measure the dissolution profiles of the samples tested. Samples were tested in a basket apparatus, as described in the Ph. Eur. and the USP, using a rotation speed of 100 rpm. The compositions of the buffers used and the test parameters were as follows:
The amount of dissolved alfuzosin hydrochloride is determined as follows:
Calculation of Extinction Coefficient:
Tablets of the invention were prepared to contain 10 mg of alfuzosin hydrochloride in a 300 mg tablet. Spray dried lactose monohydrate was employed as a water-soluble filler to maintain the weight of the tablet. Due to its water solubility, lactose monohydrate is an effective release enhancer of alfuzosin hydrochloride in the matrix system.
First attempts were made to manufacture the tablets by direct compression after blending, the active substance with suitable excipients. For this purpose 10, 30, 50 and 70% HPMC with various viscosity grades (4000 cp, 15000 cp, 100000 cp) were mixed with alfuzosin hydrochloride and lactose monohydrate as a channel forming agent. The excipients were wet granulated in a high shear mixer. After drying, the granules were collected and delumped in an oscillating granulator. Finally magnesium stearate was mixed with the granules in a cube mixer. The tablets were compressed at a hardness of 100 N and 140 N. The compositions of the produced batches are summarized in the following tables.
Dissolution profiles of Examples 1-12 were recorded and the results are shown in
Tablets were manufactured by a wet granulation process comprising the following steps:
Studies were then conducted to establish the amount (%) and viscosity grade of the gel forming HPMC in a prolonged release formulation with a release profile similar to the reference product. For that reason 70, 80 and 90% HPMC, based on the tablet weight, were employed in the test formulations. For maintaining the weight of the tablet, spray dried lactose monohydrate was employed. The sample formulations of each batch are summarized in Table 5. For each HPMC grade, one test formulation was manufactured:
Dissolution profiles of Examples 13-15 were recorded and the results are shown in
It was decided to further optimize the formulation variant with the HPMC having a viscosity grade of 15000 cP, as this formulation also shows good manufacturing properties. For that purpose, batches containing 85% HPMC instead of 80% and 24 mg instead of 12 mg of povidone per tablet were manufactured and different granulation liquids (ethanol, purified water) were tested, as shown in Table 6.
To prepare the tablets, the alfuzosin hydrochloride was mixed with HPMC and lactose monohydrate. The wet granulation process was performed as described in Examples 13-15 with the solvents modified as noted in Table 6.
Example 18 showed a decrease in bulk/tapped density due to the ethanolic granulation. The tablet could not be pressed. Granules of Example 17 showed the best flowability. This was confirmed by results of the weight variation (RSD of 1.8% for Example 16 versus 2.3% for Example 17. Therefore, the aqueous granulation is preferred to the alcoholic or water/alcohol granulation liquid.
Two additional batches containing 85% HPMC were prepared using the wet granulation process of Examples 13-15 to assess the reproducibility of the formulation. The formulations of the two batches were the same, as shown in Table 7.
*Not contained in the finished product
Dissolution profiles were recorded to compare the above mentioned formulation with two batches of the reference product. The tablets are dissolved in 0.01 N HCl solution (pH 2.0). The resulting dissolution profiles are shown in
To investigate the dependency of the alfuzosin hydrochloride release on tablet hardness, dissolution profiles were recorded in 0.01 HCl solution at pH 2.0. For this purpose, tablets containing 85% HPMC and having a tablet-hardness between 135 N and 225 N were manufactured. The resulting dissolution profiles (not shown) demonstrate that the release of the drug substance is independent of the hardness within the tested range.
While the invention has been described in detail and with reference to specific examples thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
