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Patent linkage refers to the relationship between the market approval of a generic drug and the patent status of its branded equivalent. It dictates that marketing approval for a generic cannot be granted prior to the expiration of the patent term on the branded equivalent, or until the relevant authority has determined that the branded drug’s patent will not be infringed or is invalid, unless otherwise consented by the patent owner.
The main purposes of patent linkage include early resolution of disputes on infringements and invalidity, and prevention of regulatory bodies facilitating patent infringement via their own administrative actions. In this way patent linkage enforces upon the regulatory body a responsibility to carry out patent enforcement. In pursuit of this, regulatory bodies are more likely to properly document data and ensure its transparency.
In the United States, patent linkage is statutorily recognized by the Drug Price Competition and Patent Term Restoration Act of 1984, otherwise known as the Hatch Waxman Act. In the US, the publication of “Approved Drug Products with Therapeutic Equivalence Evaluations", commonly known as the Orange Book identifies drugs which have been FDA approved based upon their safety and efficacy profiles. The Orange Book documents information on approved drugs, discontinued drugs and corresponding patents.
When filing for approval of an Abbreviated New Drug Application (ANDA) — the application for approval or a generic drug — the generic drug manufacturer must certify one of the following four grounds:
In the case of grounds 1 and 2 the FDA may grant the approval immediately. In case of ground 3 it is likely that the FDA will grant approval on the expiry of the patent term. In reference to ground 4, when certifying that the patent is not infringed or invalid, the applicant must notify the patentee of its filing and state the rationale behind these claims. The patentee has 45 days after notice to file an infringement suit, if an infringement suit is filed an automatic 30 month stay of marketing approval is placed on the drug. If patent expiration occurs within this 30 month period, the 30 month period expires, or the court determines the patent invalid within the 30 month period, the FDA can grant immediate approval to the generic drug. If the patent is determined to be valid and infringement has occurred the generic drug will not be approved until patent term expiration.
The European Union does not support patent linkage on the grounds that it is contrary to EU regulatory law as it undermines the Bolar Provision. The Bolar Provision sought to encourage quick access to the post patent market for EU generic drugs to allow for the availability of low cost drugs. The Bolar Provision permits any drug manufacturer to experiment with any patented drug, with a view of generating data that could be submitted to a drug control authority. Therefore, in direct contrast to the United States, the status of a patent application is not a ground for refusal, suspension or prevention of marketing authorization.
A glance at patent linkage globally shows that the discrepancies in its application are not exclusive to the transatlantic nations. Whilst Australia, China and Singapore have patent linkage systems that mirror the United States, Brunei, Malaysia, and Vietnam do not have patent linkage systems. Indonesia and Thailand also lack a patent linkage system, however they have experienced pressures from Pharmaceutical Research And Manufacturers Of America (PhRMA) to align to international best practices on patent linkage.1 2006 saw the responsibility of patent linkage and intellectual property in general fall away from the Food and Drugs Authority of the Philippines (FDAP).1 The FDAP can now accept and process applications without the need to verify whether there is a relevant patent. Even upon notification of a valid patent, the FDAP is exempt of honoring the patent and can grant approval for marketing of the product.
It is clear that a current lack of international consensus on intellectual property means that sovereign nations are not mandated to conform to the rules of patent linkage. Future changes such as enforcement of the TPP may change this. In light of this, the likelihood of patent linkage imposing increasingly restrictive criterion upon drug development in the world’s developing nations needs to be considered.
Avneet Heer is an analyst at DrugPatentWatch. She has a degree in biochemistry from the University of Leeds, UK, and also has a wide variety of experiences in the pharmaceutical sector. Previously she worked at UK and Ireland headquarters of Johnson & Johnson in the pharmacovigilance department, where she facilitated an international drug re-launch.