Otsuka Pharmaceutical Co Ltd v Sun Pharma ANZ Pty Ltd

This appeal arose from a pharmaceutical patent dispute about long-acting aripiprazole products. Otsuka held an Australian patent for controlled release sterile injectable aripiprazole formulations and methods. Aripiprazole is an antipsychotic agent used in treating schizophrenia and bipolar I disorder. The patent was not for aripiprazole itself as a new compound.

Instead, it was directed to particular controlled release formulations, including injectable suspensions and freeze-dried formulations that could be reconstituted before injection.

The commercial setting was straightforward. Otsuka had obtained a patent term extension that shifted the patent expiry from 18 October 2024 to 25 July 2029. That extra period would have mattered because it could delay generic competition. The extension was based on ARTG-listed ABILIFY MAINTENA kit products entered on 25 July 2014. Those kits included a vial of freeze-dried powder containing aripiprazole and vehicle, plus a separate solvent vial for injection.

Sun Pharma challenged the validity of the extension. Otsuka and related Lundbeck entities responded with cross-claims for threatened infringement and alleged contravention of section 18(1) of the Australian Consumer Law. For expedition purposes, Sun Pharma did not contest threatened infringement in relation to its proposed generic version of Otsuka’s ARTG goods, but it preserved its positions on claim construction, invalidity and the extension.

The appeal involved two connected but distinct disputes. The first concerned claim validity under sections 40(2)(b) and 40(3) of the Patents Act. The primary judge had found that the relevant patent term extension claims were limited by result and were invalid because they failed to define the invention and lacked clarity. Otsuka challenged those findings in its notice of appeal.

The second dispute concerned the patent term extension itself. Sun Pharma argued in its amended notice of contention that the extension should be held invalid on grounds other than those relied on by the primary judge. The most important of those grounds was that the claimed formulations were not “pharmaceutical substances” within the meaning of section 70(2)(a) because only active pharmaceutical ingredients, and not formulations, fall within that term for the extension regime.

The Court therefore had to decide whether formulation-based claims could support a valid extension of term, and whether the claims themselves were invalid for the drafting reasons accepted at first instance. It also had to deal with the downstream effect of those answers on infringement and ACL issues tied to Sun Pharma’s proposed generic products.

The Full Court dismissed the appeal. Its central conclusion was that Sun Pharma’s notice of contention succeeded because the formulations relied on by Otsuka were not “pharmaceutical substances” for the purposes of section 70(2) of the Patents Act. The catchwords state the point directly: the meaning of “pharmaceutical substance” for this regime is limited to active substances and does not include formulations. Once the Court reached that conclusion, the patent term extension was invalid.

The Court stated the practical consequence in clear terms. The patent expired on 18 October 2024, being the end of its ordinary 20-year term. So although Otsuka had previously obtained an extension to 25 July 2029, that later date did not survive the appeal.

The Court also dealt with the claim validity issues. It said no error had been shown in the finding that the relevant claims were limited by result, so that appeal ground would be dismissed. But the Court went on to say that, had the patent not expired, the claims would not be invalid for failure to define the invention or for lack of clarity. In other words, Otsuka appears to have succeeded on the clarity and definition points, but that success did not change the result because the extension issue was decisive.

The reasons also indicate that, although not necessary to the decision, the Court considered Sun Pharma’s other notice of contention grounds would also succeed. Those included arguments that the freeze-dried controlled release formulations did not satisfy section 70(2)(a), that the controlled release injectable formulations did not satisfy section 70(3)(a), and that the formulations were not pharmaceutical substances “per se”.

Businesses should read this decision as a warning against collapsing different legal questions into one commercial assumption. A patent can be granted. Its claims can survive some validity attacks. A product can be listed on the ARTG. An extension can even be granted administratively. Yet the extension can still fail later if the invention does not fit the statutory category required by the Patents Act.

For pharmaceutical and biotech businesses, the immediate lesson is to test extension eligibility early where the patent is directed to a formulation, suspension, depot product, freeze-dried product, dosage form or delivery system rather than the active ingredient itself. The Court’s reasoning, as reflected in the catchwords and introductory findings, treats the relevant extension concept of “pharmaceutical substance” as limited to active substances and not formulations.

If your commercial model assumes extra exclusivity based on a formulation patent, this case shows that assumption may be vulnerable.

That matters beyond litigation. Expiry dates affect launch sequencing, generic risk, investor communications, licence negotiations, supply planning and enforcement strategy. A later expiry date can materially change valuation. If that date depends on an extension, businesses should model the downside scenario that the extension may be challenged and set aside.

For generic entrants, the case shows the value of separating claim validity arguments from extension validity arguments. Even if a patentee can defend the wording of its claims, a challenger may still succeed by attacking the statutory basis for the extension. For originators, the case shows the opposite risk: winning on claim clarity may not preserve the commercially important exclusivity period.

The appeal was heard on 20 and 21 May 2025 by Burley, Rofe and Owens JJ in the Federal Court of Australia. Judgment was delivered on 1 December 2025. The appeal was from Sun Pharma ANZ Pty Ltd v Otsuka Pharmaceutical Co Ltd [2025] FCA 44.

The orders accompanying the reasons are important. The Court required the parties to provide draft short minutes of order within 14 days and made interim confidentiality directions about disclosure and publication of the reasons. The parties were also required to provide a copy of the reasons highlighting material said to be confidential. That means the public version may be subject to redactions or later orders.

Anyone relying on the case for a transaction, dispute or freedom-to-operate analysis should check the final published judgment and orders.

The available reasons also show that the Court dealt with a broad range of statutory construction materials and earlier authorities on patent term extensions, including the Lundbeck line of cases, Boehringer, Pharmacia, Spirit and Cipla. For business readers, the practical point is that the Court approached the extension issue as a serious question of statutory interpretation, not as a routine follow-on from ARTG listing or patent grant.