Background
Aristo Pharma GmbH and Stada Arzneimittel AG brought separate actions challenging Takeda’s supplementary protection certificate SPC/GB13/052 for lisdexamfetamine, the active ingredient identified for Elvanse, an attention deficit hyperactivity disorder treatment. The actions advanced the same invalidity case and were tried together under the Shorter Trials Scheme.
Lisdexamfetamine is a pro-drug consisting of lysine covalently bound to dexamfetamine. After ingestion, it is hydrolysed and releases dexamfetamine, which produces the therapeutic effect. The claimants argued that dexamfetamine—not lisdexamfetamine—was therefore the relevant “active ingredient” under the SPC Regulation. Because dexamfetamine had an earlier marketing authorisation, the claimants contended that the Elvanse authorisation was not the first authorisation for the relevant product and that the SPC was invalid.
Takeda maintained that lisdexamfetamine was a distinct active ingredient. The Elvanse regulatory materials classified it as a new active substance, and its different pharmacokinetic profile permits once-daily dosing rather than the multiple daily doses required for ordinary dexamfetamine.
The Court’s Holding
Judge Hacon held that lisdexamfetamine is the active ingredient of Elvanse within Article 1(b) of the SPC Regulation. The marketing authorisation and public assessment report, reasonably read, identify lisdexamfetamine as the active ingredient despite also describing it as a pharmacologically inactive pro-drug and identifying dexamfetamine as the active moiety responsible for the drug’s activity.
The court also held that lisdexamfetamine satisfied the applicable test on the agreed scientific facts. Its distinct pharmacokinetic profile produces a clinically significant change from multiple daily dosing to once-daily dosing, giving it a pharmacological and/or metabolic action of its own when compared with dexamfetamine. The court rejected the argument that the tests for an “active substance” under medicines legislation and an “active ingredient” under the SPC Regulation materially differ.
The court declined to follow the contrary reasoning of the German Federal Patent Court concerning the equivalent German SPC. It concluded that the UK SPC had been validly granted and dismissed both claims.
Key Takeaways
- A pro-drug may qualify as an active ingredient for SPC purposes even though it is pharmacologically inactive before being metabolised in the body.
- The regulatory classification and marketing-authorisation materials supported treating lisdexamfetamine, rather than dexamfetamine, as Elvanse’s active ingredient.
- A clinically significant pharmacokinetic difference, including a change from multiple daily doses to once-daily dosing, can establish a pharmacological and/or metabolic action distinct from that of an earlier authorised substance.
Why It Matters
The judgment supports SPC protection for pro-drugs whose molecular structure creates clinically significant properties beyond those of an earlier authorised active moiety. It also reinforces the close alignment between the medicines regulator’s identification of an active substance and the identification of an active ingredient under the SPC regime.
For pharmaceutical patent litigation, the decision limits attempts to invalidate an SPC merely because the therapeutic moiety released after administration was previously authorised. The relevant inquiry remains whether the authorised pro-drug itself qualifies as the product under the statutory test.