Plastic and nonmetallic article shaping or treating: processes – Forming articles by uniting randomly associated particles – Utilizing diverse solid particles
Patent
1995-06-07
1997-12-23
Vargot, Mathieu D.
Plastic and nonmetallic article shaping or treating: processes
Forming articles by uniting randomly associated particles
Utilizing diverse solid particles
26421111, 26421123, 264349, A61K 926, B29B 746
Patent
active
057004102
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method of producing a wax matrix.
The term `wax matrix` is used herein to mean a device chiefly associated with the controlled release or masking of a drug in the form of an active ingredient entrapped in a wax lattice.
The term `extruder` is used herein to mean a screw kneader-extruder which is in broad use chiefly in the processing of foodstuffs (cereals, protein, animal meat, fish meat, etc.) in food industry.
BACKGROUND ART
The conventional technology for the production of a wax matrix includes a fusion method, a spray method, a fusion-spray method, and so on.
Among them, the fusion-spray method is a technique under intensive research these days for the production of wax matrices. The fusion-spray method is a method for producing a wax matrix using a fluidized bed granulator, tumbling fluided bed granulator or other machine, which comprises either spraying a wax melted at a temperature over its melting point against crystals of an active ingredient, a powdery composition containing the active ingredient or a granulated version thereof or spraying a hot molten mixture of a wax and a powder (a crystalline active ingredient and a powdery excipient) in a cold atmosphere. Therefore, the fusion-spray method is not only free from the problems associated with the melting (wax) and powder (crystals and excipient particles)! but also free from the drawbacks of the spray method (residues of the organic solvent, measures for the disposal of waste gas and water, operator health management, etc.).
However, the fusion-spray method also has certain disadvantages, one of which is concerned with yields. Thus, since the wall structure of the granulator used in the fusion-spray method is made for the most part of metal, the load tends to stick to the internal wall which is of high heat conductivity. Moreover, the formation of secondary and tertiary particles due to coagulation of primary particles tends to occur in this method so that in order to insure a constant release rate of the active ingredient, it is generally mandatory to sieve off the secondary and tertiary particles following granulation.
Moreover, in the fusion-spray method in which a molten wax is sprayed, the wax must be consistently maintained at temperatures not below the melting point of the wax lest the melt will be readily solidified in the transport line and spray nozzle. Furthermore, excessive heating would result in a degradation of the active ingredient beyond the tolerable limit.
Furthermore, since the fusion-spray method is a batch method just as the other conventional methods, disadvantages are inevitable in mass production. Thus, in order that a large amount of wax matrix may be produced batch-wise in a given time period, large-scale equipment is required but the larger the equipment, the greater is the difficulty in setting production parameters and the production time is prolonged. Moreover, any batch method involves the problem of batch-to-batch variation in quality.
DISCLOSURE OF INVENTION
This invention has for its object to provide a method of producing a wax matrix free from the disadvantages of the prior art technology.
The inventors of this invention found that the above object can be successfully accomplished by utilizing an extruder which is capable of processing a substrate material in a continuous sequence and have arrived at this invention.
There is substantially no technology utilizing an extruder in the pharmaceutical field. Probably all that is known is the patent application filed by the present applicant, which discloses a method for producing a solid dispersion by means of an extruder (PCT/JP92/00470).
At this junction, the mechanism of the main part (load processing part) of the extruder is briefly described. Generally the main part of an extruder comprises a cylindrical structure called `barrel`, a die which corresponds to a delivery port, and a screw. The barrel usually comprises a plurality of unit barrels and the screw extends through them. The screw is available in vari
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Izumi Shougo
Nakamichi Kouichi
Yasuura Hiroyuki
Nippon Shinyaku Co. Ltd.
Vargot Mathieu D.
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