An important consideration for companies working in the pharmaceutical sector is the composition into which their active pharmaceutical ingredient (API) will be formulated. In practice, a formulation will be developed with the intention of achieving several desirable characteristics. These include:
- delivering the API at the relevant dose to the appropriate site to provide the desired therapeutic effect
- minimising the rate or amount of degradation of the API during storage
- maintaining the API in a desired chemical state or form
- designing a desirable route of administration (e.g. subcutaneous or oral administration rather than an intravenous infusion)
- establishing an easy to follow administration regime to facilitate patient compliance
- minimising any discomfort to the patient.
A formulation that provides some form of benefit (e.g. achieving one or more of the characteristics listed above) may be considered novel, non-obvious and useful, allowing the formulation to be eligible for patent protection. Indeed, a review of the patent literature reveals that there are a considerable number of patents claiming a variety of drug formulations.
It is therefore of considerable importance for pharmaceutical companies to ensure that any formulation they utilise does not infringe existing patents. This often first requires a comprehensive patent search and analysis to be undertaken. This article will consider some of the intricacies of how formulations are claimed in patents. In doing so, we will demonstrate why it is complicated to create searches aimed at finding relevant formulation patents amongst the noise of irrelevant patents.
Factors which complicate searching for formulation patents
A complicating factor when searching for formulation patents is that they may be drafted in a way that the API, or any excipients, are not specifically mentioned within the claims. Instances of this occur when:
- the API is claimed based on the class or type of compound it belongs to, rather than by its known name(s). For these cases the language used in the claims may be directed towards a class of compounds without necessarily stipulating an active ingredient of interest. Accordingly, a search for the API and a specific excipient may not identify the patent
- the patent claims excipients based on the class or type of compounds they belong to. General terms used within claims such as “sugars”, “salts” or “tonicity agents” can encompass a wide range of different excipients. Searching for such broad classes of excipients, without additional limitations, can identify an insurmountable number of patent families to review
- the claims recite an API based on a chemical structure. In the case of protein bio-therapeutics this could also be based on its amino acid sequence in the form of a claim to a SEQ ID No. Accordingly, a search for the name of the API and any specific excipients may not identify the patent.
An example of the difficulties concerning formulation patents – EP0941121
An example in practice can be seen in the patent EP0941121, entitled Stable lyophilized pharmaceutical substances from monoclonal or polyclonal antibodies. While this patent would later be revoked, it illustrates several of the complicating factors discussed. The independent claims of this patent are as follows (dependent claims not shown):
1. Stable lyophilized pharmaceutical preparation of monoclonal or polyclonal antibodies containing a sugar or an amino sugar, an amino acid and a surfactant.
12. Use of a combination of auxiliary substances composed of a) a sugar or an amino sugar, b) an amino acid and c) a surfactant for the production of stable therapeutic or diagnostic agents containing antibodies.
Both of these independent claims recite an active ingredient, with additional excipients, based on the class of compounds they belong to. While the dependent claims narrow to define certain excipients they do not define every excipient that could fall within that class. In contrast, there is no such narrowing of scope in the dependent claims for the active ingredient. Read as is, this formulation patent could be applicable to any polyclonal/monoclonal antibodies containing the recited excipients. Consequently, any patent search focusing solely on terms directly relating to an API, or specific excipients, may not identify this patent.
Patents such as this pose a considerable risk to a pharmaceutical company. This is because, upon approval of a drug the formulation of the drug becomes publicly available. This allows competitors to identify the formulation and, if found to fall within the scope of any of their patents, could lead to infringement proceedings.
The existence of patents such as the example above illustrates the difficulty in searching for and identifying relevant formulation patents. Accounting for the class of a compound in a search often leads to the identification of a large number of patents. While this may account for the use of broader claim language, it also results in a voluminous number of patents which must be analysed. In practice, it is not feasible to review every patent which uses terms such as “sugars”, “salts” or “tonicity agents”. Not only is this time consuming, but the vast majority of results would not pertain to the formulation of interest. In contrast, a cursory search only for the known names of the API, in combination with specific excipients, also has limitations. A search such as this runs the risk of missing relevant cases which use broader claim language.
To account for these difficulties the role, nature and function of each component within a formulation should be carefully considered. An efficient search must consider the different terminology applicable for the ingredients, as well as any potential structural components within the formulation, to design a practical search. This requires a proficient technical background within the pharmaceutical field, as well as familiarity with the language used within these types of patent. We suggest consulting with specialist searching services as well as IP professionals to ensure that the intricacies surrounding formulation patents are properly accounted for.