Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Reexamination Certificate
1993-04-07
2002-02-26
Bawa, Raj (Department: 1619)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C424S423000, C424S451000, C424S489000, C424S464000
Reexamination Certificate
active
06350462
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a carrier for use in sustained release preparation for providing a medicament, in particular, anticancer agent or antibiotic, available for medical treatment such as against cancer, neoplasm and osteomyelitis to an affected part of a patient's body. The invention also relates to a method for manufacturing the carrier.
2. Description of the Related Art
Conventionally, those medicaments such as anticancer agent and antibiotic are available for medical treatment against cancer, neoplasm, or osteomyelitis. However, these medicaments more or less have grave side effects. Furthermore when dosing a patient's body with any of these medicaments, in fact, only a small portion the dosed medicament reaches the affected part. To properly compensate for this, a novel method has been sought for selectively providing an optimum amount of the medicament to the affected part.
One method for delivering the medicament is a carrier for sustained release preparation capable of gradually releasing the medicament after burying it in the affected part of the patient's body. For example, the Unexamined Published Japanese Patent Application No. 59-101145 discloses such a method which buries a porous ceramics carrier impregnated with medicament to provide an optimum amount of the prescribed medicament to the affected part. Another Unexamined Published Japanese Patent Application No. 61-47401 discloses a carrier for use in sustained release preparation consisting of calcium-phosphate ceramic carrier having a large specific surface area and containing absorbed medicament.
Another Unexamined Published Japanese Patent Application No. 62-6522 discloses a carrier for use in sustained release preparation consisting of porous alumina granules having spatial area internally filled with a medicament. In this case, the filled medicament gradually diffuses via pores of those porous alumina granules.
Another Unexamined Published Japanese Patent Application No. 1-197429 discloses such a carrier for use in sustained release preparation which, except for an aperture to permit impregnation of a medicament, covers the surface of porous ceramic body permitting impregnation of the medicament in pores each having 10 to 30 &mgr;m of diameter by means of film having pores respectively having 10 &mgr;m and less than of diameter and 300 &mgr;m and less than of thickness.
These preceding Unexamined Published Japanese Patent Application No. 59-101145 and No. 61-47401 respectively disclose the art which initially requires a porous ceramic carrier to absorb the medicament, and then buries the porous ceramic carrier in the affected part of the patient body thereby permitting the medicament to be released from the porous ceramic carrier. Nevertheless, most of the medicament therein are not chemically absorbed in the porous ceramic carrier, but instead, medical ingredients are physically absorbed in this carrier. In consequence, immediately after being buried in the patient's body, the medicament is quickly released from the porous ceramic carrier to result in the failure to constantly provide the medical ingredients to the affected part for an extended time. Even when varying the ratio and diameter of pores of the porous ceramic carrier, actually, it is quite difficult for this carrier to properly control the amount of the released medicament.
On the other hand, the carrier for use in sustained release preparation proposed by the Examined Published Japanese Patent Application No. 62-6522 is manufactured by blending deceptive pore forming material with alumina powder followed by a shaping process and a firing process. Distribution of pore diameter of porous carrier produced by executing those processes mentioned above is dependent on the dispersed condition of the pore forming material. Therefore, if the available pore forming material unevenly disperses, then, continuous pores are generated in a region where the pore forming material of the porous carrier is concentrated. In this case, a local average of pore diameter noticeably exceeds a total average of pore diameter of the porous carrier. Therefore, the pore diameter in this region affects the sustained release characteristic of the medicament by causing the carrier to fully release the medicament in a very short period of time.
As is clear from the above description, the carrier for use in sustained release preparation disclosed in the Examined Published Japanese Patent Application No. 62-6522 tend to vary the sustained release characteristic of the medicament among carriers according to the dispersed condition of the pore forming material. As a result, any of these conventional carriers quickly release the medicament to incur unwanted side effect to the patient's body. On the other hand, any of these conventional carriers release a little amount of the medicament to nullify the effect of medical treatment.
On the other hand, the other carrier for sustained release preparation disclosed in the Unexamined Published Japanese Patent Application No. 1-197429 described above is buried in the affected part of the patient's body without shutting off the aperture provided on the surface of the porous ceramic carrier. This in turn causes the medicament to leak out of the aperture by such an amount in excess of the prescribed dosage.
As described above, any of those conventional carriers for use in sustained release preparation cannot properly and fully exert the function of the carrier itself to stably provide the medicament to the affected part of the patient's body for a long period of time.
SUMMARY OF THE INVENTION
The primary object of the invention is to provide a novel carrier for use in sustained release preparation, which is capable of selectively providing an optimum amount of a medicament to the affected part for a long period of time after being buried in the patient's body.
Another object of the invention is to provide a novel carrier for use in sustained release preparation, which is capable of stably maintaining the sustained release characteristic of a medicament without varying it at all.
Another object of the invention is to provide a novel method for manufacturing a carrier for sustained release preparation to permit manufacturers to easily produce the carrier.
Specifically, the invention provides a novel carrier for use in sustained release preparation, which comprises a porous ceramic body having a cavity for retaining a medicament and which controls release of the medicament. The porous ceramic body is capsule-shaped and has pores extending inwardly of the outer periphery thereof, each of which has a diameter substantially proportional to the distance from a outer periphery of the porous ceramic body.
Furthermore the present invention provides a novel carrier for use in sustained release preparation, which comprises a porous ceramic body having a hollow for retaining a medicament and which controls release of the medicament, wherein the porous ceramic body is capsule-shaped and has pores, and has a pore rate which decrease toward to the outer periphery of the porous ceramic body.
Furthermore, the present invention provides a novel method for manufacturing a carrier for use in sustained release preparation, which carrier comprises a porous ceramic body having a hollow for retaining a medicament and controls release of the medicament. The method comprises a step of preparing a raw material ceramics slurry, a step of preparing a preformed body containing a hollow by causing the raw material ceramic slurry to adhere on an inner wall surface of a solvent-absorbable mold, a step of firing the preformed body, thereby obtaining the porous ceramic body is capsule-shaped and has pores, each of which has a diameter substantially proportional to the distance from a outer periphery of the porous ceramic body.
Furthermore, the present invention provides a novel method for manufacturing a carrier for use in sustained release preparation, which carrier compri
Hakamatsuka Yasuharu
Horie Gen
Irie Hiroyuki
Bawa Raj
Frishauf, Holz, Goodman, Langer & Chick, P.C.
Olympus Optical Co,. Ltd.
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