NJ judge invalidates Sun patent in BromSite suit

A New Jersey court has invalidated a Sun Pharmaceuticals patent related to its anti-inflammatory eye drops BromSite in an infringement suit against generic drug manufacturer Lupin Pharmaceuticals.

The opinion, issued by the US District Court for the District of New Jersey on Thursday, said that Lupin’s generic did not infringe claims of Sun’s US patent 8,778,999 and that the patent was invalid for indefiniteness and obviousness.

Chief judge Freda Wolfson wrote that Sun’s patent was indefinite as it did not specify a critical measurement parameter on “spin time” which could affect the viscosity range of the active ingredient bromfenac.

She also said that the patent was obvious in light of US patent 6,159,458, a prior Sun Pharma related to “Sustained release ophthalmic compositions containing water-soluble medicaments”.

The ‘999 patent, first published in 2014, covers “Non-steroidal anti-inflammatory ophthalmic compositions”.

Invalidity interpretation

One of Lupin’s key defences was that the viscosity of its planned generic differed from the range outlined in claim 1 of the ‘999 patent. It also argued that the ‘999 patent method did not specify how much “spin time” had passed before it took the viscosity measurements.

Wolfson agreed that methods outlined in the ‘999 patent did not specify a minimum or maximum spin time before taking a viscosity reading.

One of the experts consulted called this gap in the method a “major problem”.

As a result, the opinion held that the claim term “viscosity” was indefinite, therefore invalidating the patent, even if Lupin was found to literally infringe the patent.

Case background

In 2018, Lupin filed an Abbreviated New Drug Application (ANDA) with the Food and Drug Administration (FDA) to market a generic of BromSite.

Sun received written notification of the ANDA from Lupin, claiming that the ‘999 patent was invalid and unenforceable and will not be infringed by the proposed generic.

Sun sued Lupin on February  15 2018, claiming the generic contained a “chemically identical bromfenac ophthalmic solution”.

Lupin argued that their generic did not infringe because it has a different viscosity and tried to challenge the validity of the ‘999 patent on the grounds of obviousness and also challenged a decision that one of the inventors of the patent failed to submit prior art in time.

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