English High Court invalidates Allergan glaucoma patent

One of  Allergan’s patents has been invalidated after it was challenged by UK-based pharmaceutical companies  Accord Healthcare and  Aspire Pharma.

In a  decision handed down on Friday, May 3, the English High Court ruled that an Allergan-owned patent was obvious in light of prior art.

The dispute concerns UK patent number 1,753,434, covering a glaucoma treatment named Lumigan 0.1, which contains 0.01% of the drug bimatoprost.

The ‘434 patent claims a formulation containing a low concentration of bimatoprost (0.01%) and a high concentration (0.02%) of a preservative called benzalkonium chloride (BAK).

As topical eye formulations are administered directly to the eye, preservatives, such as BAK, are used to maintain sterility and prevent microbial growth.

Aspire Pharma and Accord Healthcare, which both have marketing authorisations to market generic versions of Lumigan 0.1, contended that the ‘434 patent was invalid on the grounds of obviousness over prior art.

An article written by ophthalmologist Robert  Laibovitz, called “Comparison of the ocular hypotensive lipid AGN 192024 with timolol: dosing, efficacy, and safety evaluation of a novel compound for glaucoma management”, is cited as prior art.

In his judgment, Justice Richard Arnold said the key difference between claim 18 of the ‘434 patent and Laibovitz is that, whereas Laibovitz discloses the use of 00.1% bimatoprost to treat glaucoma, it does not disclose the use of 0.02% BAK.

Arnold said it was clear that in Laibovitz, the only reason why preserved formulations were not used is because they were not available at the time.

He said: “The question is whether the inclusion of BAK would be an obvious choice from a technical point of view. Laibovitz makes it clear that the only reason why preserved formulations were not used in the original study is because they were not available – it was not a deliberate decision for any scientific reason.”

Consequently, Arnold said that when repeating the prior art, BAK would be the obvious choice of preservative because it was the most commonly used. He said a team skilled in the art would be satisfied that the inclusion of 0.02% BAK was safe and tolerable.

The court concluded that the patent was invalid.

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