Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Patent
1995-04-25
1997-10-28
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
424466, 424468, 424473, A61K 924
Patent
active
056815832
DESCRIPTION:
BRIEF SUMMARY
This application is a 35USC371 of PCT/EP94/01050 filed Apr. 2, 1994.
BACKGROUND OF THE INVENTION
The present invention relates to novel pharmaceutical forms for oral administration capable of releasing active substances at controlled and differentiated rate. It is well known that the pharmaceutical forms for the oral administration are the overwhelming majority of the pharmaceutical market for numerous and diversified reasons which, in the case of tablets, are mainly determined in that they guarantee precise dosage, excellent stability of carried active materials and easy administration. In the last twenty years, of great importance has been the achievement of more and more sophisticated and diversified pharmaceutical forms, with the purpose of simplifying the posological scheme and obtaining greater patient's compliance. Such so called modified or controlled release pharmaceutical forms were aimed at, in the majority of cases, releasing the active material carried therein at constant rate in time, following a release kinetics defined as being of zero order.
In some cases it was also possible to highlight that, to a drug release at a constant "in vitro" rate, corresponded a more regular trend of plasmatic levels obtainable consequently to the administration to the patient.
If, in theory, such approach could have been correct so far as some drugs are concerned, in practice it has been noticed that, in many cases, the pharmacokinetics and pharmacodynamics of the active material in biological liquids are influenced and sometimes strictly determined by chronobiological rhythms. Furthermore, the developments of systems able to release the active material at constant rate has brought about the designing and therapeutical utilization of dosage forms more and more sophisticated that required the use of always new polymeric substances with specific properties from the technological and productive point of view. However, such polymeric materials, which are normally biocompatible are, not always biodegradable as well, and this implies that residues of these polymeric materials employed in creating grid therapeutic systems could remain in the organism and, above all, by repeated administration, cause unwanted accumulation phenomena.
In this respect, the setting in of now and then serious and, in some cases, lethal side effects occurred following the administration of the so called OROS system osmotic pump disclosed in the U.S. Pat. No. 4,160,020, 1979.
In the majority of cases, the slowing down of the active material release is obtained by utilizing gellable hydrophilic polymers capable of swelling in contact with water and/or aqueous fluids, thereby forming a gelled layer. From these systems the active material is in general released according to Fickiam type kinetics, A number of studies and research work have been carried out in the past and also recently aiming at the modulation of the release rate of active principles. This research was originated for therapeutic reasons (for instance the achievement of determined hematic and bioavailability levels of the drug) and because of practical problems related to the timing of the drug administration. Generally these studies to proposals consisting in two layer tablets, prevailingly of concentric type, and capable of a fast release of the active principle whereas the other was formulated so as to provide a slow or delayed releasing of the drug.
In some cases (WO-A-9305769 and EP-A-0384514) the outer layer is that with slow release, whereas the inner one (thus accessible only when the outer layer has fulfilled its function) is of the fast release type.
In other cases (U.S. Pat. No. 2,993,836 and U.S. Pat. No. 2,887,438) the delayed release layer forms the core of the tablet, whereas the outer coating layer is formulated for a fast or instantaneous release of a portion of the active principle.
According to further proposals two layer tablets have been disclosed in which the composition of the slow release layer was taken into consideration.
For instance in U.S. Pat. No.
REFERENCES:
patent: 2887438 (1959-09-01), Cooper et al.
patent: 2951792 (1960-09-01), Swintosky
patent: 2993836 (1961-07-01), Nash et al.
patent: 4786503 (1988-11-01), Edgren et al.
Conte Ubaldo
Giunchedi Paolo
Maggi Lauretta
APR Applied Pharma Research SA
Page Thurman K.
Spear James M.
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