Pulmonary hypertension is a potentially life-threatening condition characterized generally by abnormally high blood pressure in the lungs. United Therapeutics holds a patent for Tyvaso®, an inhaled solution formulation of treprostinil approved for the treatment of pulmonary hypertension (“PH”). But, for a certain group of PH patients, a study administering a similar medicine failed due to increased risk of death.

Liquidia, seeking to introduce its own PH treatment, challenged the patent, contending that a claim to a “therapeutically effective” amount of a medicine requires that the medicine be safe and effective for all patients to which is it could be administered, including the certain group at increased risk due to the treatment.

The Federal Circuit disagreed and upheld the validity of the patent. It noted that there was no dispute that the claimed “therapeutically effective” amount was one that “causes an improvement in a patient’s hemodynamics” and found that, when read in context, the claim language “does not import any additional efficacy limitations or any safety limitations.” Because the claim did not incorporate safety and efficacy requirements, the Federal Circuit affirmed the district court's findings that the patent enables and adequately describes treatments that would result in improvement in a patient’s hemodynamics, even if a study existed showing that the treatment might increase the risk of killing the patient. “Questions of safety and efficacy in patent law have long fallen under the purview of the FDA,” the Federal Circuit noted.