20 May 2025
In a recent decision that has implications for pharmaceutical patent strategy in Australia, the Federal Court has both clarified and complicated the rules around patent term extensions (PTEs). The case — Sun Pharma ANZ Pty Ltd v Otsuka Pharmaceutical Co Ltd [2025] FCA 44 — dealt with Otsuka’s long-acting schizophrenia treatment, ABILIFY MAINTENA, and its Australian patent for a controlled-release formulation of aripiprazole.
While Otsuka successfully held on to its five-year patent extension, key claims in the patent were struck down for being unclear. The ruling offers useful guidance — and a cautionary tale — for businesses relying on pharmaceutical patent protection.
The Background
Otsuka’s patent for ABILIFY MAINTENA was due to expire in 2024, but a PTE pushed it out to 2029. The product listed on the Australian Register of Therapeutic Goods (ARTG) was a kit combining aripiprazole powder with a vial of solvent for injection.
Several patent claims — referred to in the decision as the "PTE Claims" — covered this controlled-release formulation, describing a drug with a specific particle size and a release period of either one or two weeks once injected. Sun Pharma challenged both the validity of these claims and the extension itself.
What the Court Confirmed
The court made clear that product claims which include a process-related feature or a result-based limitation — like a drug that releases over a particular time frame — are not automatically excluded from being eligible for a PTE. What matters is whether the claim, when read as a whole, is directed to a product rather than a method or process.
Justice Downes rejected most of Sun Pharma’s arguments against the PTE itself. She confirmed that formulation claims can qualify for extension, and that inactive ingredients (excipients) don’t need to have therapeutic effects in their own right for a formulation to be eligible. She also accepted that kit-style claims may be covered by a PTE — so long as the product listed on the ARTG aligns with what's claimed in the patent.
The Catch: Clarity Is Crucial
Despite winning on PTE eligibility, Otsuka lost the battle over two of its most important claims — those that specified how long the drug would release in the body after injection.
The issue was clarity. The court found that the patent didn’t give a skilled person enough information to determine whether a given formulation actually delivered aripiprazole over the claimed one- or two-week period. While Otsuka argued that the result was tied to particle size — which was clearly defined — the evidence suggested that particle size alone couldn’t account for the full release behaviour. Other variables like formulation details, injection site, and dosing weren't adequately addressed in the patent.
This meant the claims were limited by result — but without the support needed to show how that result could be consistently achieved or tested. In short, the claims failed because they weren’t clear enough to be enforced.
Why This Matters for IP Strategy
For pharmaceutical companies, this case reinforces that:
- Including a performance outcome in a claim is fine, but only if the patent clearly teaches how that outcome is achieved.
- PTEs remain available for many types of product claims, even those that involve result-based or process-style wording — as long as the claim is to a product.
- Kit claims aren’t off the table, but you must ensure the commercial product (as listed in the ARTG) matches what’s in the claim.
This decision may offer reassurance to companies relying on formulation or delivery-based innovations, but it also warns against vague drafting — especially when describing how a drug behaves once administered.
Looking Ahead
It’s not yet known whether Otsuka will appeal, but the outcome is a reminder that patent drafting must be precise — particularly when claiming how a pharmaceutical product performs over time. The decision also arrives against the backdrop of other aripiprazole-related litigation in Australia, including a damages claim brought by the Commonwealth over a previously invalidated patent.
For businesses investing in pharmaceutical innovation, the takeaway is clear: a strong patent is not just about what you claim — it’s about how clearly you support that claim.
If you need advice on navigating PTEs, formulating defensible claims, or reviewing your patent portfolio, reach out to the IP Solved team.
