Where a substance or composition is already known to have been used in a "first medical use", it may still be patentable under Art. 54(5) for any second or further use in a method according to Art. 53(c), provided that said use is novel and inventive.
Art. 54(4) and Art. 54(5) thus provide for an exception from the general principle that product claims can only be obtained for (absolutely) novel products. However, this does not mean that product claims for the first and further medical uses need not fulfil all other requirements of patentability, especially that of inventive step (see T 128/82).
A claim in the form "Use of substance or composition X for the treatment of disease Y..." will be regarded as relating to a method for treatment explicitly excluded from patentability under Art. 53(c) and therefore will not be accepted. A claim in the form "Substance X for use as a medicament" is acceptable, even if X is a known substance, but its use in medicine is not known. Likewise, it is acceptable to have a claim in the form "Substance X for use in the treatment of disease Y", provided that such a claim involves an inventive step over any prior art disclosing the use of X as a medicament.
The treatment of a disease with a substance or composition which is already known to be used for treating said disease, where the only difference from the known treatment is in the dosage regime, is a specific further medical use within the meaning of Art. 54(5) (see G 2/08).
If an application discloses for the first time a number of distinct surgical, therapeutic or diagnostic uses for a known substance or composition, normally in the one application independent claims each directed to the substance or composition for one of the various uses may be allowed; i.e. an a priori objection of lack of unity of invention should not, as a general rule, be raised (see F-V, 7).
A claim in the form "Use of a substance or composition X for the manufacture of a medicament for therapeutic application Z" is allowable for either a first or "subsequent" (second or further) such application ("Swiss-type" claim), if this application is new and inventive (see G 5/83) and has a filing or earliest priority date before 29 January 2011. For applications filed on or after that date, if the invention is characterised by a second (or further) therapeutic use of a medicament, such an invention cannot be expressed as a "Swiss-type" claim (see Notice from the EPO in OJ EPO 2010, 514).
Claims in the form "Method for manufacturing a medicament intended for therapeutic application Z, characterised in that the substance X is used" or the substantive equivalents thereof (see T 958/94) are allowable for either a first or "subsequent" (second or further) such application, if this application is new and inventive and was filed before the date indicated above (see G 5/83). In cases where an applicant simultaneously discloses more than one "subsequent" therapeutic use, claims of the above type directed to these different uses are allowable in the one application, but only if they form a single general inventive concept (Art. 82). Regarding use or method claims of the above type, it should also be noted that a mere pharmaceutical effect does not necessarily imply a therapeutical application. For instance, the selective occupation of a specific receptor by a given substance cannot be considered in itself as a therapeutic application; indeed, the discovery that a substance selectively binds a receptor, even if representing an important piece of scientific knowledge, still needs to find an application in the form of a defined, real treatment of a pathological condition in order to make a technical contribution to the art and to be considered as an invention eligible for patent protection (see T 241/95). See also F-IV, 4.22, for the functional definition of a pathological condition.