Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Reexamination Certificate
2000-09-06
2003-07-22
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
C424S400000, C424S443000, C424S468000, C424S469000, C424S470000, C424S489000, C514S960000
Reexamination Certificate
active
06596311
ABSTRACT:
This invention relates to fast disintegrating tablets and particularly to tablets which not only disintegrate rapidly but also have good friability characteristics.
The tablets of this invention are particularly suitable for rapidly releasing a water soluble or water insoluble drug in granular or microencapsular form, e.g where the drug is for controlled, sustained or targeted release, or where the drug requires gastric protection or taste masking, etc.
BACKGROUND OF THE INVENTION
Over the past years, coated multiparticulate dosage forms have become increasingly important in the development of both controlled release and taste masked pharmaceutical formulations.
Among the variety of coating technologies, microencapsulation is widely recognised as a versatile technique for the coating of particles of active drugs to enhance their therapeutic value. Microencapsulation is achieved by two distinct processes, namely coacervation/phase separation and air suspension coating. These processes envelop small particles of the drug substance into minute, discrete, solid packages which to the naked eye appear as a fine powder.
Although in the marketplace there are many different solid dosage forms for peroral administration containing microencapsulated drugs, such as tablets, capsules, sachets, etc., presently there is a strong demand for multiparticulate palatable dosage forms characterised by a rapid disintegration time.
Such solid oral dosage forms are particularly advantageous for applying large single doses orally, since a tablet or other shaped form can be difficult to swallow especially for patients such as children and the elderly. These problems can be exacerbated when no water is available.
Chewable tablets containing coated particles of active drugs are a well-known dosage form (see for instance the textbook “Pharmaceutical dosage form—tablets” Vol. 1 edited by H A Lieberman et al. Marcel Dekker, Inc. (1989).
They are intended to disintegrate in the mouth under the action of chewing and typically they are larger than tablets which are intended to be swallowed. Advantages over dosage forms for swallowing include improved bioavailability through the immediate disintegration, patient convenience through the elimination of the need for water and patience acceptance through their pleasant taste.
Nevertheless, a common problem of chewable tablets is that chewing can cause a breakdown of the membrane that coats the active particles. Furthermore, the extent of mastication, which is associated with the length of time in which a drug remains in the mouth, plays an important role in determining the amount of taste masking. As a result, the drug's unpleasant taste and throat grittiness are often perceived by the patient.
To overcome such problems, other solid dosage forms known as fast dispersing or disintegrating tablets have been developed. Fast disintegrating tablets containing particles of active are based on the presence of one or more disintegrating agents which allow the tablet, when taken up by mouth, to disgregate quickly into many coated cores of active. However the presence of such ingredients tends to weaken the tablet's structure leading to poor friability values.
Accordingly, fast disintegrating tablets have suffered from problems due to their limited physical integrity as evidenced by their high friability compared to the conventional tablet forms. Thus fast disintegrating tablets have previously been found to fracture or chip easily and therefore require careful packaging and handling prior to placing them in the mouth. Generally as well as disintegrating agent, such tablets may also contain other pharmaceutical ingredients for example swelling agents or thickening agents which are responsible for producing, when the tablets disintegrates directly in the mouth or in a glass of water, a viscous medium that facilitates the suspension of the solid particles. As a result, the total weight of the fast disintegrating tablets can be rather high; thus such dosage forms are generally less acceptable to a patient especially when high dosage of active is required.
Freeze drying processes have been used to prepare fast disintegrating dosage forms. Depending on the manufacturing process, the product obtained is characterised by a solid dried highly porous microstructure of the soluble supporting agent (i.e. mannitol, glycine, lactose, gelatins, etc) in which the active is homogeneously dispersed. Although this technology produces a product which rapidly disintegrates in water or in the oral cavity, a drawback is represented by the poor physical integrity of its physical structure which severely limits further manufacturing operations such as forming blister packs.
Another significant drawback of the freeze drying technology in manufacturing such dosage forms is the high production costs because of the lengthy duration of each freeze drying cycle (normally from 24 to 48 hours). The complexity of the industrial plants is another important factor which prejudices the large scale use of this technology for the development of rapid disintegrating tablets. Moreover, the thermal shocks, as a direct consequence of each freeze drying cycle, might physically modify the physical-chemical properties of the outer membrane of microencapsulated particles.
There is a need therefore for a compression tablet with fast disintegrating properties and satisfactory structural integrity and especially such a tablet having a rapid disintegration time when taken by mouth (e.g. within 45-40 seconds, preferably within 30 seconds and most preferably 20 seconds or less). There is a need for a fast disintegrating tablet that is small for improved patient acceptability without reducing the clinical performance.
There is also a need for a fast disintegrating tablet (such as a tablet which disintegrates in the mouth in 75 seconds or less) having an enhanced structural integrity, for instance having a friability lower than 2.0% according to USP XXIII test; preferably lower than 1.5% and most preferably 1.0% or lower.
Further there is a need for a fast multiparticulate disintegrating tablet that can be produced on industrial scale with a simple manufacturing process based on a direct compression method of a mixture of selected ingredients.
There is also a need for a fast disintegrating tablet preferably having an extremely short disintegration time, quantifiable in less than 20 seconds, when taken directly by mouth without water and without the necessity of chewing the tablet and wherein the active is in the form of microcapsules having controlled release and/or gastro-resistance and/or taste masking properties.
Advantageously any multiparticulate fast disintegrating tablet should possess a physical integrity approaching that of a conventional tablet without limiting the disintegration performance of the tablet.
We have surprisingly found that by careful selection of ingredients, it is possible to prepare fast disintegrating tablets using conventional tableting means that have either disintegration rates which are faster than previously known tablets or show superior friability properties, or both. Furthermore we have been able to prepare fast disintegrating tablets without the need to use substances which effervesce on contact with water.
It has now been found that the above-mentioned drawbacks of previous tablets may be overcome by using a dry mixture of pharmaceutically acceptable excipients in selected amounts. This mixture comprises at least one water insoluble inorganic excipient and at least one disintegrant in appropriate amounts and optionally combined with one or more water soluble constituents.
We have surprisingly found that the disintegration time of tablets having satisfactory mechanical properties (such as hardness and friability), when placed in the oral cavity depends not only on the quantity of disintegrant used, but also on the quantity of the insoluble inorganic excipient and if present soluble excipient and the relative weight ratio between these components (disintegrant, insoluble excipient
Eurand International S.p.A.
Evans Charesse L.
Thompson Hine LLP
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