CAFC redefines the singular phrase “a patient” as a plural patient population

Ryan Chirnomas | November 18, 2014

Braintree Laboratories, Inc. v. Novel Laboratories, Inc.

April 22, 2014

Panel: Dyk, Prost Moore. Majority opinion by Prost. Concurrence by Dyk. Dissent by Moore.


In this ANDA litigation, the claims recited a composition for purgation of the colon of “a patient”. The majority imported the preamble phrase of “a patient” into the claim, and also interpreted this as not a single patient, but rather a “patient population”. Judge Moore dissented on this point. Additionally, Judge Dyk dissented on the grounds that the majority based its analysis on an accused infringing product different from the subject of the ANDA application, contrary to Hatch-Waxman rules.


Braintree is the owner of U.S. Patent No. 6,946,149, directed to a solution used in preparation for colonoscopies. After an ex parte reexamination, the representative claim reads as follows:

A composition for inducing purgation of the colon of a patient, the composition comprising from about 100 mL to about 500 mL of an aqueous hypertonic solution comprising an effective amount of Na2SO4, an effective amount of MgSO4, and an effective amount of K2SO4, wherein the composition does not produce any clinically significant electrolyte shifts and does not include phosphate. Emphasis added.

Braintree sells a product called SUPREP, which is a kit including two six ounce (177 mL) bottles, which are diluted to two 16 ounce (497 mL) solutions and consumed by a patient. SUPREP avoids undesirable electrolyte shifts, which were associated with previous small-volume colonoscopy prep treatments and which in some cases led to very serious medical issues. This suit arises out of an ANDA application filed by Novel, seeking to sell a generic version of SUPREP. Braintree’s argument was based on a “one bottle” theory of infringement directed to a single diluted 497 mL bottle.

The district court’s claim constructions of “purgation” and “clinically significant electrolyte shifts” were disputed. As to “purgation,” there was a dispute as to whether this refers to full cleansing of the colon, or clearing of the colon amounting to less than a full cleansing. It was undisputed that a single bottle of SUPREP would give rise to less than a full cleansing, and that two bottles were needed in order to result in a full cleansing of the colon. Novel pointed to the specification where it was indicated that the invention is “effective” if it causes a full cleansing of the colon in order to prepare for a colonoscopy.   Novel additionally pointed to Braintree’s statements in reexamination proceeding referring to “cleansing (i.e., purging).” However, the CAFC disagreed, and concluded that “purgation” is not equivalent to “cleansing”. The court relied on the plain meaning of the claim terms, and noted that “cleansing” is a preferred embodiment, but is not required by the claims. The court also noted that two different terms are presumed to have different meanings, and that Braintree’s “i.e.” comment in reexamination is insufficient to amount to a clear disavowal of claim scope.

Next, “clinically significant electrolyte shifts” was in question. The district court initially construed this as requiring “alterations in blood chemistry that are outside the normal upper or lower limits of their normal range or other untoward effects.” However, the district court later changed its interpretation to requite both blood chemistry outside the normal range and other untoward effects, based on the presumption that shifts in blood chemistry are only “significant” if they cause adverse health effects. Novel challenged this construction on the grounds that it ignores a clear definition in the specification. Meanwhile, Braintree argued that the district court’s interpretation was improper because it would exclude a preferred embodiment (where a preferred solution did cause shift outside normal ranges). However, relying on the clear definition in the specification, the CAFC indicated that the initial “or” interpretation was correct.

In view of the above constructions, the court turned to an infringement analysis. Since a single dose of the SUPREP product and a generic version thereof would cause purging of the colon and “cleansing” was not required, the CAFC indicated that the “purgation” limitation was satisfied.

As to the requirement that the composition “does not produce any clinically significant electrolyte shifts,” the court turned back to the preamble, and imported the recitation of “a patient.” The district court interpreted “a patient” as one or more patients, in line with conventional practice. Furthermore, the district court indicated that at least one patient could take SUPREP without significant electrolyte shifts. Braintree supported the district court’s interpretation of “a patient” as one or more patients. However, Novel argued that this interpretation was improper, and would lead to an inappropriate conclusion of infringement even if 99 out of 100 patients experience significant electrolyte shifts.

Surprisingly, the majority agreed, arguing that district court’s interpretation leads to an “absurd” result. Relying on passages in the specification that refer to patients generally, the majority interpreted “a patient” as a “patient population” that is the normal class of people to which the treatment is directed. In other words, the majority interpreted “a patient” as plural “patients,” not including a singular patient. Since the record showed that some patients have electrolyte shifts outside the normal range, the majority remanded to the district court to address the factual question as to whether SUPREP avoids clinically significant electrolyte shifts in a “patient population.”

The opinion also addressed validity of the ‘149 patent, but this topic is omitted for brevity.

Dyk’s concurrence

Judge Dyk agreed with the majority claim construction, but dissented with respect to whether Novel’s ANDA satisfies the claimed volume requirement of 100-500 mL. Dyk noted that in ANDA litigation, it is the content of the ANDA itself which defines the infringing act. Since Novel was seeking regulatory approval for a full 946 mL dosage of the product, Dyk argued that the infringement analysis must be based on this dose, not the single bottle addressed in the majority opinion. As such, Dyk argued in favor of non-infringement, based on failure to meet this claim limitation. Furthermore, Dyk indicated that even in the absence of an ANDA issue, in view of the specification, the volumes recited in the claims refer to the total dosage, not a fraction thereof. Thus, Dyk rejected Braintree’s “one bottle” theory of infringement.

Moore’s dissent

Moore agreed with the majority, but dissented with respect to the construction of “a patient” as excluding a single patient. Moore indicated that CAFC precedent requires that the indefinite article “a” should be interpreted as “one or more.” When the CAFC deviated from this, it was only where intrinsic evidence made it clear that “a” meant “one and one only.” As to the majority’s concern regarding the “absurd” situation where infringement would be found even where 99 of 100 patients experienced electrolyte shifts outside the normal range, Moore argued that this is a question of damages, not a question of infringement. Normally, such “rare infringement” would result in low damages, but since this is pre-market ANDA litigation, damages are not available. Instead, Moore argued, the only proper result of infringement is postponement of regulatory approval until expiration of the patent. However undesirable, Moore argued that this is more appropriate than the majority’s construction of “a patient” to mean “multiple patients.”

Take aways

Although the circumstances giving rise to the majority’s interpretation of “a patient” are unlikely to occur in many patents, this case serves as a good reminder that there are no absolutes in claim construction. However, in the case of medical methods or compositions reciting functional language, this is an unsettling result. By interpreting “a patient” as a patient population, the CAFC has effectively rewritten the claim terms, and possibly introduced a question of indefiniteness and enablement, since it is unclear precisely how many patients constitute a “population”. As noted by Judge Moore, the standard for patent infringement is quite different from the efficacy standard for FDA approval. In view of decision, it may be prudent to include an explicit definition of a patient, subject, etc as a singular entity in the specification.

Additionally, although not groundbreaking, the court’s comments regarding “purgation” and “cleansing” are a good reminder to take care when using two similar terms. One should use the terms as consistently as possible, since a deviation from this may give rise to different interpretations. Here, Braintree’s remarks in reexamination referring to “cleansing (i.e., purging)” did not detrimentally affect claim construction, but perhaps could have if used in a different context.

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