Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Reexamination Certificate
1998-11-10
2001-08-21
Spear, James M. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
C424S465000
Reexamination Certificate
active
06277407
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to tablet fabrication, and more particularly to the production of tablets through the use of a tableting press that compresses powders and granules.
2. Background Information
Tableting presses have long been utilized to manufacture tablets by compressing powders and granules. A typical tableting press uses a cylindrical die center made of steel, and steel punches, to compress the powder under relatively high pressures, typically up to about 10 to 15 tons per square inch. One result of the compression is the production of heat. This heat builds up on the face of punches and in the die and, over a relatively short period of time, tends to cause the powder to stick to the faces of the punches and sides of the die. Once the powder begins to stick to the die and/or to the punch faces, the integrity of the tablet is compromised, since as the faces of the punches pull apart to eject the tablet, the tablet sticks to the punch faces and breaks, or is broken or damaged by the friction with the cylindrical walls of the die. Moreover, any powder remaining on the punches and/or die walls tends to add to the volume of powder within the die, to disadvantageously alter the internal pressure of the tablets. Tablets formed under excessive pressure may not dissolve properly, while tablets formed under insufficient pressure tend to break prematurely.
In order to reduce the die and face heat, and reduce the sticking on the face of the punches and the sides of the dies, it has been common practice to add powdered lubricants to the powdered tablet composition. These lubricants generally encase the powdered granules to reduce the friction on the face of the punches and the sides of the die. Commonly used lubricants include magnesium stearate and other stearates, such as sodium stearate and calcium stearate. Stearates tend to be useful as lubricants because of their relatively high viscosity and insolubility in water, which helps prevent their breakdown when used to make compressed tablets.
While the use of stearates may be satisfactory in some applications, such as in the production of pharmaceuticals, their use tends to be undesirable in tablets that are dissolved in water prior to ingestion. Due to their hydrophobic nature, the stearates tend to float to the top of the water when a tablet made using stearates is dissolved in water, creating an undesirable metallic sheen or film on the surface of the water.
Thus, when manufacturing a water soluble tablet it is important to reduce or eliminate any insoluble material in the composition. One attempt to manufacture water soluble tablets involves replacing hydrophobic lubricants, such as stearates, with water soluble lubricants such as polyethylene glycol. While the use of such water soluble lubricants tends to reduce sticking on the sides of the die, these lubricants by themselves do not adequately prevent the tablet composition from sticking to the faces of the punches. This sticking problem is particularly acute when producing relatively large tablets, in which the tablet tends to be pulled apart when the punches separate prior to the tablet's ejection from the press. In particular, over multiple cycles, the composition adhered to the faces of the punches tends to accumulate to undesirable levels to the point at which uniform tablets may no longer be produced.
Thus, a need exists for an apparatus and method for fabricating water soluble tablets which overcomes the drawbacks of the prior art.
SUMMARY OF THE INVENTION
According to an embodiment of this invention, a tablet press is provided for the manufacture of a tablet by compression of tablet material in the form of powder or granules. The tablet press includes at least one die circuitously moveable about the press and adapted for receiving tablet material therein; and a first punch and a second punch, the first and second punches being circuitously moveable with, and being adapted for operative engagement with, the at least one die. A punch movement device is adapted to alternately move at least one of the first and second punches relatively towards and away from an other of the first and second punches to alternately compress the tablet material in the at least one die to form the tablet, and release the tablet. A punch cleaner is disposed in operative engagement with the first and second punches, the punch cleaner being adapted to remove tablet material from the first and second punches after each of the first and second punches has released the tablet.
The present invention provides, in a second aspect, a rotary tablet press for the manufacture of a tablet by compression of tablet material in the form of a powder or granules. The rotary press includes a plurality of dies rotatable around a central axis of the press; a plurality of first and second punches rotatable with the dies; a feeder for introducing tablet material to each of the dies at a filling station; and a punch movement device adapted to alternately move the first and second punches relatively towards and away from one another to alternately compress the tablet material in the dies between working faces of the upper and lower punches to form tablets, and release the tablets. An ejector is provided for removing the released tablets from the plurality of dies; and a punch cleaner is disposed in operative engagement with the plurality of upper and lower punches, the punch cleaner being adapted to remove tablet material buildup from the working faces after each of the upper and lower punches has released the tablets.
The present invention provides, in a third aspect, a method is provided for fabricating a water soluble tablet adapted to dissolve in non-carbonated water. The method includes the steps of:
(a) providing a tablet press including:
at least one die circuitously moveable about the press and adapted for receiving tablet material therein;
a first and second punch, the first and second punches being circuitously moveable with, and being adapted for operative engagement with, the at least one die;
a punch movement device adapted to alternately move at least one of the first and second punches relatively towards and away from an other of the first and second punches to alternately compress the tablet material in the at least one die to form the tablet, and release the tablet;
a punch cleaner disposed in operative engagement with the first and second punches, the punch cleaner being adapted to remove tablet material from the first and second punches after each of the first and second punches has released the tablet;
(b) introducing tablet material in the form of powder or granules to the at least one die;
(c) moving the at least one of said first and second punches relatively towards the other of said first and second punches to compress the tablet material within the at least one die to form the tablet;
(d) moving the at least one of said first and second punches relatively away from the other of said first and second punches to release the tablet;
(e) engaging the punch cleaner with said first and second punches to remove tablet material therefrom.
The above and other features and advantages of this invention will be more readily apparent from a reading of the following detailed description of various aspects of the invention taken in conjunction with the accompanying drawings.
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Sampson & Associates P.C.
Spear James M.
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