The Patent office decision in LTS Lohmann Therapie-Systeme AG and Schwarz Pharma Limted  APO 16, rejecting an application for an extension of patent term, highlights the care which must be taken in drafting claims to drug delivery systems such a transdermal patches if such an extension is to be successfully obtained.
LTS sought an extension of term under section 70 for an invention relating to a “transdermal therapeutic system”. As summarised by the Hearing Officer, the relevant claims of the patent where directed to a pharmaceutical compound comprising three components, namely (a) a matrix layer comprising the active pharmaceutical ingredient and a non-aqueous adhesive polymer (b) a backing layer inert to the ingredients of the matrix, and (c) a protective layer to be removed before application.
The only issue of significance was whether the claims of the patent were directed to a pharmaceutical substance per se as required by section 70. Recognising the difficulty in satisfying this condition due to the presence of the backing and protective layers, LTS sought to characterise these features as equivalent to the binders or excipients used in tablets and capsules. Alternatively, LTS argued that the backing and protective layers were not essential to the claimed invention.
In relation to the essential nature of the backing and protective layers, the Hearing Officer pointed to concessions by LTS as to the significance of those layers in the successful and effective administration of the drug. Further, even if the backing and protective layers were not in fact essential to the working of the invention, they were clearly essential limitations of the relevant claims.
Regarding the nature of the “pharmaceutical compound” as claimed, the Hearing Officer referred to the decision in N. V. Organon  APO 8 and concluded:
Prima facie, the presence in NEUPRO® of an inert backing layer and a protective layer which is removed before use, would exclude it from being a “compound of substances” for the purposes of s 70. However, following the reasoning in Organon, these layers would not be fatal to an extension if the patentee could demonstrate that the product as a whole shows a level of integration or interaction between the component parts such that it would fall within the definition of a pharmaceutical substance under the Act. However, LTS’s submissions during prosecution of the extension have been that the backing and protective layers constitute separate and subsidiary physical integers, that “in no way contribute to the working of the therapeutic substance”. This position is wholly inconsistent with NEUPRO® as a whole, being considered “a substance (including a mixture or compound of substances)” within the definition of Schedule 1.
Accordingly, while the meaning of “a pharmaceutical substance per se” may well be broader following Organon, the condition will not be satisfied where claims clearly recite features which constitute separate and subsidiary physical integers.