Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Web – sheet or filament bases; compositions of bandages; or...
Reexamination Certificate
1999-10-01
2001-08-21
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Web, sheet or filament bases; compositions of bandages; or...
C424S449000, C424S443000
Reexamination Certificate
active
06277400
ABSTRACT:
The invention relates to an active ingredient-containing transdermal therapeutic system with a nonadhesive backing layer, with an active ingredient-containing reservoir layer and with a self-adhesive surface facing the skin, where appropriate with redetachable protecting layer.
It has been known ever since the Middle Ages that pharmaceutical active ingredients can migrate through the human skin and thus medicinal effects can be achieved by preparations of pharmaceutical active ingredients being placed or spread on the skin. These effects are not confined to the skin and the underlying tissue but may, with appropriately suitable substances, extend to remote organs because the active ingredients are, after absorption, distributed by the blood circulation. Transdermal therapeutic systems (TTS) which define not only the active ingredient concentration used but also the application area exactly have in the past become established as novel pharmaceutical administration forms because they provide the required properties in a particularly user-friendly manner.
The possible TTS embodiments have some basic features in common:
1. To prevent unwanted release of active ingredient or else moisture from the skin through the transdermal therapeutic system to the outside, also to prevent adhesion to textiles, an essentially impermeable, nonadhesive backing layer is used.
2. Since transdermal therapeutic systems are intended to adhere to the skin, the layer facing the skin, and occasionally only part of the contour, is made self-adhesive.
3. Because of the self-adhesive properties, a redetachable protecting layer is applied for storage before use.
The backing layer usually consists of pharmaceutically customary materials such as plastic sheets; but paper, nonwovens, textiles and metal foils are also mentioned.
TTS of these types are, despite the advances made, nevertheless also associated with some disadvantages. Thus, the active ingredient-impermeable backing layer with a stable area restricts the comfort of wearing for the patient, the “stiffness” or lack of extensibility of the sheets used in practice results in a limitation to areas with a size of 40 cm
2
. However, since the area-related transport rate through the skin is very low for most pharmaceutical active ingredients, a larger area for the system would be very desirable in order to be able to offer marketable TTS also for such active ingredients.
There have already been attempts to improve the comfort of wearing by using elastic materials for the backing layer (for example U.S. Pat. No. 5,246,705) but in this case express attention was paid to the impermeability of the material for the advised drug.
It is unfortunate in principle that all elastic and plastically extensible polymeric raw materials suitable for the TTS backing layer are diffusible for most TTS active ingredients, so that transdermal therapeutic systems produced therewith generally display the problem of potential losses of active ingredient (evaporation through the outer surface of the backing layer), especially when very volatile active ingredients are employed.
It is an object of the invention to provide a transdermal therapeutic system with an elastic or plastically extensible backing layer which displays improved stabilization, by comparison with the prior art, against evaporation of the active ingredient present.
This object is achieved according to the invention with a TTS of the type mentioned at the outset, which is characterized by an elastic or plastically extensible diffusible backing layer with a metal layer which acts as permeability barrier for auxiliaries and active ingredients in the reservoir layer and is formed by film growth, in particular a layer resulting from metal vapour deposition. Further particular features are evident from the dependent claims and the description.
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Horstmann Michael
Laux Wolfgang
Muller Walter
Ghali Isis
Hochberg D. Peter
Holt William H.
LTS Lohmann Therapie-Systeme AG
Page Thurman K.
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