Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Patent
1996-12-17
1998-11-10
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
424489, 514777, A61K 946, A61K 916
Patent
active
058340190
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP95/01904 filed May 19, 1995.
BACKGROUND OF THE INVENTION
The invention relates to a pharmaceutical formulation comprising an effervescent system and at least two different surfactants or emulsifiers. In the case of the pharmaceutical formulation containing an effervescent system, hydrophobic active substances give rise to considerable difficulties, which are even greater in the case of loratadine: apart from the formation of active substance rings on the glass, the dissolution of an effervescent tablet is also substantially slowed down. A particular composition of the effervescent system, as may be useful, for example, for acid-, alkali- and/or metal-sensitive active substances, is of no further assistance here.
For example, loratadine is virtually completely water-insoluble (2.5 mg/liter) and has a very strongly hydrophobic character. It is thus extremely poorly wettable and therefore difficult to suspend. Its fine particles furthermore have the tendency to form a film on the water surface, to creep up the glass wall to a pronounced extent and to adhere relatively strongly there; the coarser particles sink to the bottom; in addition, dissolution of a conventional, loratadine-containing effervescent tablet gives rise to foam formation, resulting in dissolution behaviour which is unsuitable with regard to marketing. Moreover, up to 10% of the active substance is lost as a result of adhesion to the glass.
A further problem is the small dose of 10 mg of active substance per tablet, which, in an effervescent tablet, must achieve the content uniformity required in accordance with the pharmaceutical guidelines. This requirement, too, cannot be met by mixing the active substance with an effervescent base. It is also desirable to have a small effervescent tablet of about 1 to 1.5 g, which makes the problem more difficult to solve.
In order to improve the poor suspension properties of loratadine, attempts have already been made, according to EP A1 241 469, to treat the active substance with wetting agents, such as docusate sodium or sodium laurylsulphate, with or without a binder. It was found that the use of these wetting agents did not achieve the aim, either by direct application of the surfactant to the active substance or to a mixture of the active substance with a filler, such as mannitol or sorbitol, or by addition of the surfactant to the effervescent base. On dissolution of the effervescent tablet, the active substance treated in this manner and present therein exhibited excessively strong foam formation, which could not be substantially reduced even by adding an antifoam, and another disadvantage observed was that the active substance is not suspended but collects in the foam on the water surface.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a pharmaceutical formulation for hydrophobic active substances, in particular for loratadine, which takes into account the physical behaviour of such active substances. However, there must be no other undesirable side effects, such as, for example, foam formation. Furthermore, even small amounts of active substance must be capable of being distributed as uniformly as possible in an effervescent tablet, and the weight of the effervescent tablet should be capable of being kept as low as possible.
These objects are achieved and problems solved for the first time surprisingly by use of at least two different surfactants or emulsifiers; particular embodiments and further developments of the inventive concept are described below and in the appended claims. The invention is first illustrated in more detail using loratadin as an example. For the purposes of the invention, "surfactant" is to be understood as meaning the wetting agents which are in particular (not but exclusively) ionic, are conventionally used in pharmacy and reduce the surface tension, as well as docusate sodium, sodium laurylsulphate, etc. It is particularly expedient if, in addition to such a "surfactant", the formulation according to the inv
REFERENCES:
patent: 5158779 (1992-10-01), Gergely et al.
patent: 5645856 (1997-07-01), Lacy et al.
patent: 5646131 (1997-07-01), Badwan et al.
Gergely Gerhard
Gergely Irmgard
Gergely Thomas
Gerhard Gergely
Page Thurman K.
Spear James M.
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