Second medical use claims guidance on infringement

Second medical use claims guidance on infringement

On 13 October 2016 the Court of Appeal handed down its decision in the case of Warner-Lambert vs the generics company Actavis (UK) Ltd and others.

This is the latest decision in a long running dispute between these parties, relating to the second medical use protection of the product Pregabalin. It had been hoped that this decision would provide some guidance on the infringement of the second medical use patents and how generic companies can safely launch onto the market.                     

Background to the case

Pregabalin was originally used for treating general anxiety disorder and epilepsy. The patent covering this use expired in 2013. Warner-Lambert now markets it for the treatment of neuropathic pain, which was protected by the patent in suit by second medical use claims. Actavis and Mylar, generics companies, requested revocation of the patent. Actavis also launched a generic version of Pregabalin, and so Warner-Lambert started infringement proceedings.

The three main issues discussed in the decision were sufficiency of disclosure, abuse of procedure and infringement.


For a patent to be valid it must disclose the invention clearly and completely enough for it to be carried out over the whole scope by the skilled person without undue burden.

The patent was found to be insufficient. The claims were directed to the use of Pregabalin in the treatment of pain, in particular neuropathic pain. The experimental models used could not measure the effects on the central nervous system. Therefore, it was not plausible that the compound could be used to effectively treat central neuropathic pain, only peripheral neuropathic pain.

This decision provides guidance on the requirements of the specification in order to meet the sufficiency requirements. It must be plausible that the invention has the claimed effect. The specification needs to accurately predict that the invention will work based on a reasonably credible theory or there must be data in the specification, such that the reader is encouraged to try the invention. For pharmaceutical cases, it is not necessary to provide full clinical trial data. In vitro data which shows that a claimed compound has an effect in a model or system, which is known to be associated with a specific condition to be treated, can be enough to meet the requirements. Ideally a patent application should only be filed once there is conclusive evidence that the claimed effect can be achieved.

Abuse of procedure

At the end of the trial, Warner- Lambert sought permission to amend the claims. The other parties objected, stating this was an abuse of procedure. This opinion was supported by the judges who refused to allow amendments to the claims. In UK court proceedings it is possible to amend the claims after trial. However, this is only allowed in cases where claims have been found to be partially valid, and the claims are amended to delete the invalid subject matter.

In this case, claims relating to peripheral neuropathic pain were considered to be sufficient. However, there was not a claim directed to peripheral neuropathic pain. In the absence of such a claim, it would be necessary to introduce a new claim. There was no word for word reference to treating neuropathic pain in the application, so any new claim would need to be to relate to pain caused by damage to peripheral nervous system. This essentially meant writing a new claim.

The other parties, and the judge, considered that by writing a new claim, the trial would need to be re-run and this is an abuse of procedure. The amended claims should have been filed earlier ie before the trial started, so they could be considered during the course of the trial. A second hearing is not allowed. Whilst this would have been difficult in the present case, as the opponents had not formulated their sufficiency attack clearly in the written proceedings before the trial, the judge said that the need to file the amendments could have been foreshadowed.

Possible claim amendments should be filed in any proceedings as soon as possible. Once a trial hearing has begun, it is almost impossible to make claim amendments unless it is to restrict the claims to valid subject matter which is clearly defined in the claims considered during the trial.


Although the patent was held to be invalid through lack of sufficiency, the judge is still provided some insight and advice on potential infringement of second medical use claims.

Second medical use claims cover the subsequent use of a known compound. The compounds are already known and used for treating a first condition. This causes problems created by the prescribing system used in the UK. There needs to be proper reward for the patentee for their contribution to the art (ie identifying new conditions which can be treated)  whilst not excluding competitors from making and marketing the same compound for the previous purpose which is no longer protected by a patent.

The judges decided that infringement occurs if the manufacturer is able to foresee that there will be intentional use for the new medical indication. Intentional use is to be distinguished from use with the drug is prescribed for different indication, and without it in any sense being the intention of the treatment, a pain condition is in fact treated. The absence of the patented indication from the label (so called 'skinny labelling') was not sufficient to negate the intention. The competitor needs to take all reasonable steps within their power to prevent to the infringement. 

Unfortunately, the judges did not state how infringement can be avoided. However, they did refer to a decision in France where in addition to 'skinny labelling', the manufacturer contacted doctors and pharmacists prior to launch stating that the product was not to be prescribed for the patented condition. In addition, the manufacturer agreed to send more explicit messages to doctors and pharmacists in cities and hospitals describing how to prescribe and dispense the generic form of the drug without infringing the second medical use patent.

What to take from this

Generic manufacturers need to ensure that they take sufficient steps to avoid infringement of a second medical use patent. This may involve 'skinny labelling' as well as informing medical professionals such as doctors and pharmacists of the limited use of the generic version.

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