Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Reexamination Certificate
1997-09-19
2001-02-06
Dees, José G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
C424S451000, C424S457000, C424S463000, C424S464000, C424S468000, C424S474000, C424S475000
Reexamination Certificate
active
06183780
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an oral delayed immediate release formulation, to a method for preparing such a formulation and to the combination of a delayed immediate release formulation with an immediate release formulation.
DESCRIPTION OF THE RELATED ART
In general, the aim of medicinal treatment is to deliver an amount of an active substance to the target site within the body, to maintain the necessary therapeutic concentration of the active substance at the target site for some period of time and to avoid the presence or accumulation of the active substance at the non-target site. The concentration of the active substance at the target site as a function of time may be of minor importance as long as the therapeutic concentration is reached and not the toxic level. In this case a simple formulation can be used for administration of the active substance. Sometimes a relatively constant concentration of the active substance may be desired, in which case the active substance may be administered in the form of an appropriate slow release formulation. In a number of situations, however, it is believed that beneficial therapeutic effects can be achieved when the active substance is administered in such a manner that the administration is matched to variations in the body in the course of the 24: hours day. This goal can simply be achieved by administering a normal immediate release formulation just before the point in time that a high concentration of active substance is desired, leading to an immediate pulsatile release of the active substance. In some cases, however, e.g. when said point in time is during the night or early in the morning, the administration can only be performed with severe burden to the patient. In that case, but also in all other cases where improvement of patient compliance is desirable, the active substance can be administered via a formulation that releases the active substance after a certain predetermined lag-time, if desired combined with an immediate release formulation.
Several approaches are known to the preparation of formulations that release active substance after a certain pre-determined lag-time. EP 0210540 describes the so called Time-Controlled Explosion System, a system principally consisting of a swellable core and an outer membrane of water-insoluble material. In this system the release mechanism is based on the fact that gastro-intestinal fluids penetrate through the coating and cause the swelling agent to swell. This swelling results in an “explosion” of the coating, which is followed by the release of the drug. It is claimed that the lag-time of the system can be controlled by the coating thickness. The major disadvantage of this system is that it is not suitable for obtaining a pulsatile release in combination with a longer (6 to 14 hours) lag-time. The variation in lag-time is high, due to the high elasticity of the coating and the irreproducible swelling of the mentioned swelling agents. Moreover, it has been observed that the release is not pulsatile, but requires several hours (1 to 3). Only when short lag-times are used, real pulsatile release occurs.
WO 93/19741 also describes a pharmaceutical formulation for time-controlled release of active substance. In this formulation the release mechanism is based on the fact that the core, containing the active substance, is covered with an erodable layer or a combination of erodable layers, at least one of the erodable layers containing, as a major constituent a water-soluble cellulose derivative or a mixture of water-soluble cellulose derivatives. The disadvantage of this formulation is that it is not easy to prevent leakage during the lag-time, especially when longer lag-times are desired. Furthermore it is difficult to obtain a pre-determined lag time, especially longer than 7 hours, in a reliable and reproducible way.
OBJECTS OF THE INVENTION
It is the purpose of the present invention to deliver a formulation that releases the active substance immediately after a certain pre-determined lag-time in a pulsatile manner, without substantial leakage taking place during the lag-time, Furthermore the lag-time should be controlled in a reliable and reproducible way and it should be possible to produce the formulation by relatively simple and inexpensive formulation methods.
SUMMARY OF THE INVENTION
This goal can be achieved by an Oral Delayed Immediate Release formulation comprising a compressed core containing one or more active substances surrounded with a coating, wherein release of active substance from the core is caused by rupture of the coating after a definite lag-time, said core comprising one or more immediate release carriers and having no substantial swelling properties upon exposure to gastrointestinal fluids.
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patent: 4798724 (1989-01-01), Khanna
patent: 4897270 (1990-01-01), Deutsch et al.
patent: 5229131 (1993-07-01), Amidon et al.
patent: 5286497 (1994-02-01), Hendrickson et al.
patent: 0420459 (1990-09-01), None
patent: 0396425A (1990-11-01), None
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patent: 0502642A (1992-09-01), None
patent: 0655240A (1995-05-01), None
patent: 9319741 (1993-10-01), None
Elbers Jules A. C.
Frijlink Henderik W.
Philips Wienman E.
Van Balken Paulus M.
Dees Jos,e G.
Duphar International Research B.V.
Shelborne Kathryne E.
Stevens Davis Miller & Mosher L.L.P.
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