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

Updated: Nov 10, 2020

Endo Pharmaceuticals Inc., et al.


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.

.04 Case summary of Endo Pharmaceuti

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