United States: Reformulated OxyContin Patents Invalid

Purdue Pharma L.P., et al. v. Epic Pharma, LLC, et al.

Addressing product-by-process limitations and inherent anticipation issues, the US Court of Appeals for the Federal Circuit affirmed the district court's ruling that the asserted claims of Purdue Pharma's patents covering reformulated OxyContin are invalid. Purdue Pharma L.P., et al. v. Epic Pharma, LLC, et al., Case Nos. 14-1294, -1296, -1306, -1307, -1311, -1312, -1313, -1314 (Fed. Cir., Feb. 1, 2016) (Prost, CJ).

The case concerns four patents related to a version of the pain reliever OxyContin. Three of the patents relate to an improved formulation of oxycodone hydrochloride, which is the active ingredient (API) of OxyContin. The fourth patent covers abuse-resistant formulations of OxyContin.

The first three patents (referred to herein as the low-ABUK patents) describe an oxycodone salt with extremely low levels of a particular impurity (14-hydroxy), which belongs to a class of potentially dangerous compounds known as alpha, beta unsaturated ketones (ABUKs). Purdue scientists discovered that the source of the 14-hydroxy impurity was an oxidation byproduct called 8-alpha, which transformed into 14-hydroxy during the synthesis process. To remove the 14-hydroxy impurity from the API, Purdue included an extra hydrogenation step to convert the 14-hydroxy into oxycodone free base.

The district court found the three low-ABUK patents to be obvious, explaining that using hydrogenation to remove 14-hydroxy was well known, and that the discovery of 8-alpha was not necessary to the claimed invention. According to the district court, "a skilled artisan would recognize that hydrogenation could be used to remove the remaining 14-hydroxy, regardless of the source of the 14-hydroxy." The district court also concluded that because the claims were directed to a product, the process limitation requiring the 14-hydroxy to be derived from 8-alpha was immaterial to the obviousness determination.

Purdue appealed, relying heavily on the seminal 1923 Supreme Court of the United States Eibel Process decision for the proposition that "where an inventor discovers a nonobvious source of a problem and then applies a remedy in response, the invention is nonobvious and worthy of a patent—even if the remedy, standing alone, would generally appear to be known in the art." According to Purdue, because the source of the 14-hydroxy was not obvious, the solution must also be nonobvious.

The Federal Circuit found the Eibel Process decision inapplicable, explaining that unlike Eibel, Purdue did not claim the remedy of the problem (performing an extra hydrogenation step), but instead claimed only the end product itself (oxycodone with low ABUK levels). Purdue also argued that without knowing the source of the 14-hydroxy impurity, a person of ordinary skill in the art would not know when or how to perform the hydrogenation step. The Federal Circuit again disagreed, noting that Purdue claimed the end product, not a method for creating that product. As such, the only issue was whether a person of ordinary skill in the art would find it obvious to use hydrogenation to remove the 14-hydroxy—the source of the 14-hydroxy is irrelevant.

Purdue next argued that the district court erred in concluding that the claim language "wherein at least a portion of the 14-hydroxy is derived from 8-alpha . . ." was a process limitation that was immaterial to the obviousness analysis. The Federal Circuit agreed with the district court, noting that the "derived from 8-alpha" limitation does not describe the structure of 14-hydroxy or impart any structural or functional differences in the ultimate end product. According to the Federal Circuit, there was no suggestion in the patents that the hydrogenation process changes depending on the source of the 14-hydroxy impurity. Because the claims at issue were product-by-process claims, the district court properly focused on the product and not the process of making it.

With respect to the fourth patent, the issue was whether the prior art inherently disclosed tablets having the specific breaking strength required by the asserted claims. According to the inventors, a crush-resistant formulation (having a breaking strength of greater than 500N) reduced the potential for abuse, as the original OxyContin tablets were easily crushed into powder, allowing them to be swallowed, snorted or injected.

The district court found the asserted claims of the fourth patent to be anticipated, crediting the experimental work and testimony of defendant's expert Dr. Fernando Muzzio, who recreated a process disclosed in a key prior art reference, McGinity. Using the McGinity process, Dr. Muzzio made thousands of tablets, then tested them for breakage strength. Each and every tablet made according to McGinity had a breaking strength of over 500 nM. The district court thus concluded that the McGinity reference "inherently discloses a breaking strength greater than 500N, because the experimental results indicate unanimously, reliably, clearly and convincingly that any tablet made according to the McGinity Application would exhibit this characteristic."

Reformulated OxyContin Patents Invalid

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

To print this article, all you need is to be registered on Mondaq.com.

Click to Login as an existing user or Register so you can print this article.

In association with
Related Video
Up-coming Events Search
Font Size:
Mondaq on Twitter
Register for Access and our Free Biweekly Alert for
This service is completely free. Access 250,000 archived articles from 100+ countries and get a personalised email twice a week covering developments (and yes, our lawyers like to think you’ve read our Disclaimer).
Email Address
Company Name
Confirm Password
Mondaq Topics -- Select your Interests
 Law Performance
 Law Practice
 Media & IT
 Real Estate
 Wealth Mgt
Asia Pacific
European Union
Latin America
Middle East
United States
Worldwide Updates
Check to state you have read and
agree to our Terms and Conditions

Terms & Conditions and Privacy Statement

Mondaq.com (the Website) is owned and managed by Mondaq Ltd and as a user you are granted a non-exclusive, revocable license to access the Website under its terms and conditions of use. Your use of the Website constitutes your agreement to the following terms and conditions of use. Mondaq Ltd may terminate your use of the Website if you are in breach of these terms and conditions or if Mondaq Ltd decides to terminate your license of use for whatever reason.

Use of www.mondaq.com

You may use the Website but are required to register as a user if you wish to read the full text of the content and articles available (the Content). You may not modify, publish, transmit, transfer or sell, reproduce, create derivative works from, distribute, perform, link, display, or in any way exploit any of the Content, in whole or in part, except as expressly permitted in these terms & conditions or with the prior written consent of Mondaq Ltd. You may not use electronic or other means to extract details or information about Mondaq.com’s content, users or contributors in order to offer them any services or products which compete directly or indirectly with Mondaq Ltd’s services and products.


Mondaq Ltd and/or its respective suppliers make no representations about the suitability of the information contained in the documents and related graphics published on this server for any purpose. All such documents and related graphics are provided "as is" without warranty of any kind. Mondaq Ltd and/or its respective suppliers hereby disclaim all warranties and conditions with regard to this information, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. In no event shall Mondaq Ltd and/or its respective suppliers be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of information available from this server.

The documents and related graphics published on this server could include technical inaccuracies or typographical errors. Changes are periodically added to the information herein. Mondaq Ltd and/or its respective suppliers may make improvements and/or changes in the product(s) and/or the program(s) described herein at any time.


Mondaq Ltd requires you to register and provide information that personally identifies you, including what sort of information you are interested in, for three primary purposes:

  • To allow you to personalize the Mondaq websites you are visiting.
  • To enable features such as password reminder, newsletter alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our information providers who provide information free for your use.

Mondaq (and its affiliate sites) do not sell or provide your details to third parties other than information providers. The reason we provide our information providers with this information is so that they can measure the response their articles are receiving and provide you with information about their products and services.

If you do not want us to provide your name and email address you may opt out by clicking here .

If you do not wish to receive any future announcements of products and services offered by Mondaq by clicking here .

Information Collection and Use

We require site users to register with Mondaq (and its affiliate sites) to view the free information on the site. We also collect information from our users at several different points on the websites: this is so that we can customise the sites according to individual usage, provide 'session-aware' functionality, and ensure that content is acquired and developed appropriately. This gives us an overall picture of our user profiles, which in turn shows to our Editorial Contributors the type of person they are reaching by posting articles on Mondaq (and its affiliate sites) – meaning more free content for registered users.

We are only able to provide the material on the Mondaq (and its affiliate sites) site free to site visitors because we can pass on information about the pages that users are viewing and the personal information users provide to us (e.g. email addresses) to reputable contributing firms such as law firms who author those pages. We do not sell or rent information to anyone else other than the authors of those pages, who may change from time to time. Should you wish us not to disclose your details to any of these parties, please tick the box above or tick the box marked "Opt out of Registration Information Disclosure" on the Your Profile page. We and our author organisations may only contact you via email or other means if you allow us to do so. Users can opt out of contact when they register on the site, or send an email to unsubscribe@mondaq.com with “no disclosure” in the subject heading

Mondaq News Alerts

In order to receive Mondaq News Alerts, users have to complete a separate registration form. This is a personalised service where users choose regions and topics of interest and we send it only to those users who have requested it. Users can stop receiving these Alerts by going to the Mondaq News Alerts page and deselecting all interest areas. In the same way users can amend their personal preferences to add or remove subject areas.


A cookie is a small text file written to a user’s hard drive that contains an identifying user number. The cookies do not contain any personal information about users. We use the cookie so users do not have to log in every time they use the service and the cookie will automatically expire if you do not visit the Mondaq website (or its affiliate sites) for 12 months. We also use the cookie to personalise a user's experience of the site (for example to show information specific to a user's region). As the Mondaq sites are fully personalised and cookies are essential to its core technology the site will function unpredictably with browsers that do not support cookies - or where cookies are disabled (in these circumstances we advise you to attempt to locate the information you require elsewhere on the web). However if you are concerned about the presence of a Mondaq cookie on your machine you can also choose to expire the cookie immediately (remove it) by selecting the 'Log Off' menu option as the last thing you do when you use the site.

Some of our business partners may use cookies on our site (for example, advertisers). However, we have no access to or control over these cookies and we are not aware of any at present that do so.

Log Files

We use IP addresses to analyse trends, administer the site, track movement, and gather broad demographic information for aggregate use. IP addresses are not linked to personally identifiable information.


This web site contains links to other sites. Please be aware that Mondaq (or its affiliate sites) are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of these third party sites. This privacy statement applies solely to information collected by this Web site.

Surveys & Contests

From time-to-time our site requests information from users via surveys or contests. Participation in these surveys or contests is completely voluntary and the user therefore has a choice whether or not to disclose any information requested. Information requested may include contact information (such as name and delivery address), and demographic information (such as postcode, age level). Contact information will be used to notify the winners and award prizes. Survey information will be used for purposes of monitoring or improving the functionality of the site.


If a user elects to use our referral service for informing a friend about our site, we ask them for the friend’s name and email address. Mondaq stores this information and may contact the friend to invite them to register with Mondaq, but they will not be contacted more than once. The friend may contact Mondaq to request the removal of this information from our database.


This website takes every reasonable precaution to protect our users’ information. When users submit sensitive information via the website, your information is protected using firewalls and other security technology. If you have any questions about the security at our website, you can send an email to webmaster@mondaq.com.

Correcting/Updating Personal Information

If a user’s personally identifiable information changes (such as postcode), or if a user no longer desires our service, we will endeavour to provide a way to correct, update or remove that user’s personal data provided to us. This can usually be done at the “Your Profile” page or by sending an email to EditorialAdvisor@mondaq.com.

Notification of Changes

If we decide to change our Terms & Conditions or Privacy Policy, we will post those changes on our site so our users are always aware of what information we collect, how we use it, and under what circumstances, if any, we disclose it. If at any point we decide to use personally identifiable information in a manner different from that stated at the time it was collected, we will notify users by way of an email. Users will have a choice as to whether or not we use their information in this different manner. We will use information in accordance with the privacy policy under which the information was collected.

How to contact Mondaq

You can contact us with comments or queries at enquiries@mondaq.com.

If for some reason you believe Mondaq Ltd. has not adhered to these principles, please notify us by e-mail at problems@mondaq.com and we will use commercially reasonable efforts to determine and correct the problem promptly.