Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Patent
1995-05-05
1997-08-05
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
424480, 424482, 424483, 424493, 424494, 424497, A61K 932, A61K 950
Patent
active
056540043
DESCRIPTION:
BRIEF SUMMARY
This application is a 35 USC 371 of PCT/JP93/01608 filed Nov. 5, 1993.
TECHNICAL FIELD
The present invention relates to an oral pharmaceutical preparation which is releasable in the lower digestive tract. In particular, the present invention relates to a pharmaceutical preparation for oral administration which passes through the stomach without being affected by gastric juice, does not undergo any change in the small intestine, and begins to disintegrate for the first time when it arrives at the large intestine to release the active ingredient, which is absorbed therein.
BACKGROUND ART
The pharmaceutical preparations for oral administration according to the prior art begin to disintegrate or dissolve before the arrival at the large intestine. Therefore, it has been a practice in the prior art to employ an intravenous, intranasal or rectal administration method in the administration of an active substance which is expected to exhibit a local action on the large intestine or is decomposed by the lyase present in the small intestine.
However, an oral pharmaceutical preparation has the following advantages. Namely, if an oral pharmaceutical preparation releases a pharmacologically active substance selectively in the large intestine, the concentration of the active substance at the release site can be increased to give a more effective local action than that of the preparation according to the prior art. Further, if a pharmacologically active protein or peptide which is decomposed in the small intestine loses its activity and is released selectively in the large intestine, the protein or peptide will be able to be absorbed in the large intestine wherein the protease activity is poor. Owing to the above advantages, it is apparent that an oral pharmaceutical preparation is a dosage form far more useful than injection or suppository.
For the reason described above, many attempts have recently been made to develop oral pharmaceutical preparations targeting the large intestine.
For example, there have been reported an oral preparation targeting the large intestine, which is prepared by combining a polymer soluble only at a pH of 5.5 or above with an insoluble polymer (EP40590); a solid oral preparation coated with a suitable amount of an anionic polymer soluble at a pH of 7.0 or above (trade name: Eudragit S, a product of ROHM) (WO83/00435); an oral preparation coated with a mixture comprising an anionic polymer soluble at a pH of 7.0 or above (trade name: Eudragit S or L, a product of ROHM) and a methacrylate copolymer difficultly soluble in water (trade name: Eudragit RS, a product of ROHM) at a suitable ratio (EP225189); an osmotic-pump preparation coated with an enteric polymer (BE903502); a colon-reaching oral preparation covered with an inner coat soluble at a pH of 7.0 or above, an intermediate coat made of a gelatinized polymer, and a acid-resistant outer coat soluble at a pH of 5.5 or above (Japanese Patent Publication No. 501411/1992); and so forth.
All of these preparations are characterized in that a drug is released by a pH increase in the intestinal tract, and they are each prepared by applying a proper amount of an anionic polymer or by adding or applying an insoluble polymer to prevent the drug from being released during its residence in the small intestine.
Meanwhile, a recent study on humans (D. F. Evans, Gut, 1988, vol.29, p.1035) reported that the pH of the intermediate and lower parts of the small intestine ranges from 7.4 to 7.5 (standard deviation: 0.4 to 0.5), while the average pH rapidly drops to 6.4 (standard deviation: 0.4) in the upper part of the large intestine and gradually increases to reach 7.0 (standard deviation: 0.7) in the lower part of the large intestine.
However, all of the above oral preparations releasable in the large intestine according to the prior art are coated with a polymer soluble or swelling at a pH of 7.0 or above, on the assumption that the pH in the colon or large intestine is 7.0 or above. The inventors of the present invention have also made intensive stu
REFERENCES:
patent: 4432966 (1984-02-01), Zeitoun et al.
patent: 4775536 (1988-10-01), Patell
patent: 4780318 (1988-10-01), Appelgren et al.
patent: 4780322 (1988-10-01), Martani et al.
patent: 4996047 (1991-02-01), Kelleher et al.
patent: 5296236 (1994-03-01), Santus et al.
Nakanishi Masaru
Okayama Minenobu
Hisamitsu Pharmaceutical Co. Inc.
Page Thurman K.
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