Baxter Healthcare Corp. v. HQ Specialty Pharma Corp.

Case Name: Baxter Healthcare Corp. v. HQ Specialty Pharma Corp., Civ. No. 13-6228 (JBS/KMW), 2015 U.S. Dist. LEXIS 128002 (D.N.J. Sept. 23, 2015) (Simandle, C.J.) 

Drug Product and Patent(s)-in-Suit: Brevibloc^® (esmolol hydrochloride); U.S. Patents Nos. 6,310,094 ("the '094 patent") and 6,528,540 ("the '540 patent") 

Nature of the Case and Issue(s) Presented: Baxter owns the patents-in-suit, which claim a ready-to-use aqueous esmolol hydrochloride formulation used to treat acute cardiac disorders. The patented formulation differs from previous esmolol solutions because it does not break down in the presence of water, and terminal sterilization does not degrade its potency. HQ filed its ANDA seeking approval to sell generic esmolol products in 10 mg/mL and 20 mg/mL dosage forms, prior to the expiration of Baxter’s patents. HQ’s product included esmolol hydrochloride as the active ingredient, and listed several other ingredients that it classified as buffering agents, stabilizers, and pH adjusters. In response, Baxter filed suit. The court requested that the parties resolve the issue of claim construction in the context of summary-judgment motions related to the issue of infringement.

The issue here concerns whether the court’s claim-construction determination was sufficient to grant cross-motions for summary judgment relating to infringement. The questioned turned on the court’s interpretation of the claim term "osmotic-adjusting agent". The court denied HQ’s motion to strike Baxter’s cross motion for summary judgment and also construed the term "osmotic-adjusting agent" to mean "an agent to adjust the tonicity of the solution." The court also denied each party’s cross-motions for summary judgment.

Why HQ Prevailed: First the court addressed HQ’s motion to strike Baxter’s motion for summary judgment. HQ argued that Baxter had unfairly changed its proposed construction of the term "osmotic-adjusting agent". According to HQ, Baxter originally construed the term to mean a discrete component "that adjusts the osmotic pressure of the composition." During the most recent round of briefing, also according to HQ, Baxter shifted its proposed construction to mean "a component that stabilizes the esmolol formulation for autoclaving." The court rejected HQ’s argument and found ample evidence in the record that Baxter had continued to pursue its latter construction throughout the briefing.

Turning to claim construction, HQ argued that for the purposes of the patents-in-suit, Baxter had attempted to adopt a special definition of "osmotic-adjusting agent" that was separate from its ordinary meaning. The court determined that after reviewing the intrinsic evidence, it was clear that Baxter had disavowed any meaning of "osmotic-adjusting agent" beyond an "agent to adjust [the] tonicity of the [claimed] invention." The court specifically cited to a portion of the specification of the ’094 patent which stated that  the "present invention provides a stable, ready-to-use parenteral solution containing esmolol hydrochloride and a pharmaceutically acceptable buffering agent and an osmotic adjusting agent to adjust the tonicity of the solution." The ’540 patent specification contained a similar disclosure. The court also noted that the patents-in-suit made no reference to osmotic pressure. The court also determined that the patent drafters used of the phrase "present invention" to limit the term osmotic-adjusting agent to an agent that adjusts the tonicity of the claimed solution. The court also credited HQ’s argument that Baxter had admitted that the osmotic-adjusting-agent claim term should be defined to mean "to adjust the tonicity of the solution" because it made such an admission while prosecuting the European equivalent of the ’094 patent. The court did note that admissions made in foreign counterpart patent prosecution should be treated with caution due to differences in U.S. and foreign patent law. But that concern was not an issue here. Accordingly, the court construed the term "osmotic-adjusting agent" to mean "an agent to adjust the tonicity of the solution."

Next, the court addressed the parties’ cross-motions for summary judgement, which it ultimately denied because genuine issues of fact still existed. For example, Baxter relied on two pieces of evidence that supported its position that propylene glycol and ethanol act as tonicity adjusters: (i) its experts, who testified that "consistent with the science of injectable pharmaceutical formulations…agents that adjust osmotic pressure also adjust tonicity"; and (ii) various patents and patent applications that "specifically describe propylene glycol as a tonicity-adjusting agent." The court found that neither source of evidence was sufficient to entitle Baxter to summary judgment. Here, Baxter must show that propylene glycol and ethanol actually functioned as a tonicity agent within the claimed invention, which HQ clearly disputed. Indeed, the ’540 patent specification created an impression that prior art esmolol solutions only used ethanol and propylene glycol "to increase solubility of the esmolol," and not for the purpose of adjusting tonicity. Thus, the court denied Baxter’s cross-motion for summary judgement.

The court also denied for two reasons HQ’s summary-judgment motion. First, HQ claimed that "ethanol and propylene glycol have a function distinct from that of the ‘osmotic-adjusting agents’ in the patents-in-suit," and therefore could not and did not adjust the tonicity of the claimed esmolol solutions. HQ relied the asserted patents’ description of the claimed esmolol formulation as being "essentially free from propylene glycol and ethanol", and contrasting the claimed invention to prior art that added "propylene glycol and ethanol" in order to increase solubility. The court disagreed, finding that such a position ignored the reality that common components of a formulation often performed multiple functions. Second, HQ argued that ethanol and propylene glycol did not adjust the tonicity of the claimed esmolol formulations. But HQ’s evidence for this position was based on an incomplete statement by Baxter’s expert. The expert did not state unequivocally that ethanol and propylene glycol did not adjust tonicity. Instead, he merely stated that he did not recall any research demonstrating that to be the case. Therefore, the court also denied HQ’s cross motion for summary judgment.