03 December 2025
Abbey Laboratories Pty Ltd v Virbac (Australia) Pty Ltd (No 3) [2025] FCA 1179
In a recent decision, Jackman J of the Federal Court handed down a detailed ruling in Abbey Laboratories Pty Ltd v Virbac (Australia) Pty Ltd (No 3) — a case that dives deep into the complexities of inventive step, novelty, and patent validity in the veterinary pharmaceutical field.
The Background
The patent at the centre of the dispute, titled “Veterinary Topical Formulation”, claimed a stable pour-on treatment for cattle containing levamisole and a macrocyclic lactone, both dissolved in a non-aqueous solvent system. Abbey Laboratories (Abbey) sought to revoke several claims, while Virbac (Australia) Pty Ltd (Virbac) cross-claimed for infringement — alleging Abbey’s “Levomax Duo” product breached multiple claims if the patent was found valid.
Abbey began advertising and selling Levomax Duo in late 2024, prompting Virbac to pursue court action. An interlocutory injunction was denied in December 2024, allowing sales to continue pending trial.
Inventive Step: The Crux of the Battle
Both sides presented expert evidence from highly qualified witnesses, including veterinarians and formulation scientists. The key issue was whether a person skilled in the art (PSA), as of the 2011 priority date, would have arrived at the claimed formulation without inventive ingenuity.
While non-aqueous solvent systems were already common in pour-on cattle products, the question was whether the choice of specific solvents (such as dimethyl acetamide and dimethyl isosorbide) and the resulting stability represented an inventive step.
Jackman J preferred the evidence of Professor Craig Bunt (University of Otago) over that of Abbey’s expert, Dr Fadil Alawi, finding that a PSA would not have selected the claimed solvents based solely on common general knowledge. As a result, Abbey’s inventive step challenge largely failed — most claims were upheld as inventive.
Novelty: Prior Art Under Scrutiny
Abbey’s novelty attack centred on a prior art patent known as the 984 patent, which described parasiticidal compositions with multiple active agents. However, the court found the prior art did not disclose the specific combination or solvent system claimed in Virbac’s patent.
In essence, a skilled reader would still need to make multiple technical choices — from actives to solvent type — meaning the claim retained novelty.
The Outcome
Jackman J ultimately held that:
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Claims 19–21 were invalid due to lack of inventive step;
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All other claims, including claim 1, remained valid; and
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Abbey infringed the valid claims through its Levomax Duo product.
Virbac was granted declarations and injunctions, with Abbey given four weeks for an orderly product wind-down. Costs and pecuniary relief remain pending.
Why It Matters
This case reinforces that inventive step assessments remain nuanced, especially in pharmaceutical and formulation patents. Even small compositional differences can sustain patent validity if they’re not obvious from existing knowledge — a reminder for innovators that meticulous documentation of problem-solving steps is crucial.
For competitors, it’s a warning: launching a “similar” product without a thorough freedom-to-operate (FTO) analysis can quickly cross the infringement line.
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