Searching Markush formulae directed to medical applications

Markush formulae are beyond any doubt the most efficient way of claiming a generic group of compounds. Indeed they are necessary to give applicants adequate protection for their invention. However, due to their complex nature, it is not always straightforward to determine their exact scope.The present paper looks at two extremes of Markush structures, which are unsearchable as such, the so-called “A-B-C type molecules” and “too simple compounds”. Appropriate patentability search strategies, including non-unity and incomplete searches, are defined.Frequently, claimed Markush formulae partially overlap with prior art generic structures. Criteria for selecting the most relevant documents in such cases are discussed, including novelty and inventive step aspects of selection inventions. In a case study, the use of different search tools is compared.