Understanding loss of exclusivity

The ‘loss of exclusivity date’ (LoE) is the date that generic or biosimilar manufacturers can launch their own versions of a product onto the market. This does not mean that generic and biosimilar products will become available on that date, only that they could.

The LoE date is the latest of:

• the date of loss of relevant patent protection
• the date of loss of data exclusivity and market protection

Once exclusivity has been lost, other factors such as commercial viability will influence whether and when a generic or biosimilar becomes available.

Patents

A patent usually protects an invention for up to 20 years from the date the patent is filed.

However, new medicines cannot be marketed for several years after the discovery of the active drug and filing for a patent. This is due to the time required to conduct clinical trials and obtain regulatory approval. Therefore, additional protections are available for new medicines:

• a Supplementary Protection Certificate (SPC) – this can extend protection for up to five years
• a Paediatric Extension (PE) – this can extend an SPC for an additional six months

Protection for a new drug entity can therefore last for up to 25 years and six months.

It is also possible to patent other aspects of a medicine, such as different drug salts, formulations, or delivery devices. Additional patents such as these can further extend patent protection for a medicinal product.

Patents can ‘fall’, or be invalidated, due to litigation. They can also expire early if renewal fees are not paid. If this happens, generics or biosimilars may appear earlier than expected.

To learn more, visit our Understanding patents article.

Data exclusivity and market protection

A new medicine is usually marketed many years after the drug is first patented. Patent protection can therefore expire shortly after the new medicine has been introduced to the market.

To compensate, additional rules ensure that manufacturers of new medicines have a reasonable period of exclusivity before generic or biosimilar versions are marketed.

These rules are separate from patent protection.

Data exclusivity

Generic or biosimilar manufacturers cannot use the originator’s trial data in their licence application for eight years after the originator’s product is licensed.

Market protection

Generic or biosimilar manufacturers cannot place their product on the market for 10 years after the originator’s product is licensed. Even if they already have a product licence, they must wait to put the product on the market.

If the originator adds a significant new indication to their product licence, market protection can be extended to 11 years.

Orphan medicines

Orphan medicines are licensed to diagnose, prevent, or treat rare conditions that are life-threatening or chronically debilitating. ‘Orphan’ status grants up to 10 years of market exclusivity from the date of first approval of the product for that indication. Orphan medicines with paediatric indications may be eligible for an additional two years of exclusivity, for a total of 12 years.

To learn more, visit our Understanding data exclusivity and market protection article.

Estimating the date of loss of exclusivity

The only factor affecting the date of loss of exclusivity that is not subject to change is the 10-year minimum period of market protection. This means that when a new drug enters the market, generic or biosimilar versions will not appear for at least 10 years.

However, all other factors may change over time.

A product may gain additional protections, extending the period of exclusivity. Protections may also be lost, such as when patents are declared invalid.

Some protections are easy to find out about:

• the UK Intellectual Property Office has a website where patent, SPC and PE dates can be checked if you know the relevant patent number
• the UK Orphan Products Register is available online

However, other protections are more difficult.

For example, there is no easy way to determine whether a product has been given an extra year of market protection due to a significant new indication.

Patent litigation is complex and estimating which side is likely to win can be difficult.

If the patent-holder wins, then the patent – and exclusivity – usually stays the way it is. If the challenger wins and the patent falls, then the date of loss of exclusivity may change abruptly. Generics or biosimilars could become available immediately if they are already licensed.

Even if all the factors protecting exclusivity are known, it can be difficult to interpret them. For instance, a product may have a patent protecting its formulation. Generic or biosimilar manufacturers may be able to ‘avoid’ the patent by formulating their own versions differently. How likely they are to do this will depend on how easy it is to reformulate the product – which can be difficult to judge.

All these factors mean it may not always be possible to estimate a date of loss of exclusivity with certainty. There may be several possibilities, depending on which protections a manufacturer is likely to apply for, and the likelihood of existing protections failing.

Other factors affecting market entry

Some products may have additional factors affecting the likelihood of a generic or biosimilar medicine being marketed, even when exclusivity has been lost.

Inherent complexity

Some drug molecules are inherently complicated and difficult to copy or manufacture.

Example

Botulinum toxin is a very complex molecule. The patent on Botox® (botulinum toxin type A) ran out years ago. However, creating a new botulinum toxin and licensing it as a new drug is easier than trying to copy Botox®.

Lack of commercial interest

Even after a drug loses all potential protections, no generic or biosimilar may appear if it is not commercially viable.
This could happen if:

• the patient population is very small
• there are many other medicines available in the same therapeutic category

Example

Tanatril (imidapril) has lost exclusivity. However, sales are so low (£50,000/year in 2024/25) compared to other ACE inhibitors (total £48 million) that it may not be worth marketing a generic of it.

Lack of manufacturer presence in the UK

If a manufacturer has no existing presence in the UK, it may not be commercially viable to launch a product in the UK, even if it has been licensed abroad. This is because a sales and distribution network is required.

Finding information on when loss of exclusivity will occur

Information on patents is publicly available, but usually difficult to find and interpret. The following resources may help you.

Prescribing Outlook, our annual planning document, includes information on drugs we believe will lose exclusivity over the next four years. This document is confidential to the NHS, so you must be logged in to access it.

The MHRA publishes lists of new product licences granted every two weeks. A product licence may be granted a considerable time (two years or more) in advance of the intention to market the product. However, the existence of a product licence is an indicator that exclusivity is likely to end within the next couple of years.

As new drugs benefit from at least 10 years’ market protection, you can check the date of first authorisation in the Summary of Product Characteristics (SmPC). Generics or biosimilars are unlikely until at least 10 years after first authorisation.

Find UK Summaries of Product Characteristics:

• on the electronic Medicines Compendium
• on the MHRA website

If you do wish to look at patent or Supplementary Protection Certificate records, you can search the Intellectual Property Office’s database.