• Fred Hadidi

Federal Circuit finds method of treating kidney patients with oxymorphone as being patent-eligible

Endo Pharmaceuticals Inc., et al. v. Teva Pharmaceuticals USA, Inc., et al.

2017-1240, 2017-1455, 2017-1887

Decided: March 28, 2019

Case Summary

In addition to removing waste products from the blood, kidneys also filter out drugs and their metabolites. When kidney function is impaired, the rate at which both waste products and drugs are filtered is decreased; for patients who take medications, this makes it difficult to determine proper dosage.

Endo pharmaceuticals, manufacturer of the opiate oxymorphone, recognized that patients with impaired kidney function could be treated effectively—and without a dangerous buildup of the drug in their bloodstreams—by adjusting dosage based on the severity of the patient's kidney impairment: the greater the impairment, the lower the dosage.

Endo’s US Patent No. 8,808,737 covers a method for treating pain in renally impaired patients that includes the steps of providing a specified oral dose of oxymorphone; measuring the patient's creatinine clearance rate (“CCR,” which is correlated with a patient's level of kidney function); placing the patient into one of four categories of kidney function; and—based on the patient's measured CCR—choosing a lower dose of the drug so that the 12-hour average level (the “area under the curve,” or “AUC”) of the drug in the patient's blood is within a specified range.

Endo sued Teva, Barr, and Actavis in Delaware for infringing the ‘737 patent. The defendant responded with a motion to dismiss, arguing that the claims are patent-ineligible under §101 because they are directed to the natural law that the bioavailability of oxymorphone (that is, its level in the blood) is increased in patients with renal impairment.

The District Court agreed with the defendants, finding under step one of the Supreme Court’s Alice/Mayo patent eligibility test that the claim is directed to a natural law; and finding under step two that the claim does not add enough to the underlying natural law to become a patent-eligible application of that law.

In reversing the lower court, the Federal Circuit said the District Judge was wrong to have found the claim ineligible simply because it includes an underlying ineligible concept. The Supreme Court has cautioned that "all inventions at some level embody, use, reflect, rest upon, or apply laws of nature, natural phenomena or abstract ideas;" therefore, the proper question under step one of the Alice/Mayo test is whether the claim is "directed to" a natural law or abstract idea—not whether it is possible to identify one underlying the claim. Here, the panel said that the claim at issue recognizes a natural law—the relationship between the bioavailability of oxymorphone and the degree of a patient's renal impairment—but it does not claim that patent-ineligible relationship. Rather, it claims “a method of treatment including specific steps to adjust or lower the oxymorphone dose for patients with renal impairment," which is a specific application of that relationship. The claim is therefore not "directed to" a natural law, and is patent-eligible.

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