The recent uptick and rise in popularity of GLP-1 drugs for addressing weight loss and obesity has led to an increase in U.S. litigation involving this class of drugs. Over the past few years, litigation has focused on a wide range of issues including patent and other IP disputes, product liability, regulatory challenges, importation concerns, and legal issues concerning the availability of compounded versions of GLP-1 drugs in view of the U.S. Food & Drug Administration (FDA)-declared drug shortages.
Compounded Drugs and FDA-Declared Drug Shortages
Due to the increased popularity of GLP-1 drugs for treatment of diabetes and for weight management, many of the FDA-approved drugs have experienced drug shortages over the past few years. In contrast to the FDA-approved GLP-1 drugs, compounded drugs are typically created by licensed pharmacists for individual patient needs and are not subject to the same rigorous FDA review process for safety and efficacy. Entities may only sell compounded drugs that are identical to an FDA-approved drug when that drug is on the FDA drug shortage list. Although compounded drugs may be legally sold during a declared drug shortage, the compounded drugs must still comply with certain other legal and regulatory requirements directed to quality and safety issues.
Finding an inability of brand name GLP-1 manufacturers to keep up with patient demand for approved GLP-1 drugs, the FDA temporarily placed many of the approved GLP-1 drugs on the FDA shortage list, leading to an increase in the availability and sale of compounded drugs containing the active ingredient. This in turn led to significant litigation between brand name GLP-1 manufacturers and groups representing entities selling compounded drugs.
For example, brand name GLP-1 manufacturers have filed numerous lawsuits against entities manufacturing and selling compounded versions of their drugs, alleging a wide range of claims including failure to comply with regulatory requirements, trademark infringement, violation of consumer protection laws, and various allegations directed to mispresenting and deceiving patients as to the regulatory status of the compounded versions.
As brand name manufacturing capacity has increased to meet patient demand, the FDA has removed some of the GLP-1 drugs from the drug shortage list, leading to lawsuits filed by the compounding pharmacies against FDA. For example, FDA removed tirzepatide from the drug shortage list in October 2024. In response, Outsourcing Facilities Association filed a lawsuit against FDA in the Northern District of Texas on behalf of its members, challenging FDA’s decision to remove the drug from the drug shortage list as arbitrary and capricious. The matter was remanded back to FDA for reconsideration, and FDA issued a decision in December 2024 confirming the drug shortage was resolved. Most recently, in March 2025, the district court denied the plaintiff’s motion for a preliminary injunction, finding FDA’s decision to remove tirzepatide from the drug shortage list was proper. That case is now on appeal.
A similar round of lawsuits was filed in 2025 following FDA’s decision to remove semaglutide products from the drug shortage list.
Given the ongoing popularity and high demand for GLP-1 drugs in the U.S., we expect both sides to continue litigating over these issues.
Patent Litigation
To date, patent infringement lawsuits have largely followed the framework under the Hatch-Waxman Act applicable to generic drug manufacturers who seek FDA approval to market generic versions of approved drugs (“reference listed drugs”) by filing Abbreviated New Drug Applications (ANDAs). The ability to even file an ANDA is subject to applicable FDA exclusivity periods. One of the relevant exclusivity periods applies to New Drug Applications (NDA) for approved products containing new chemical entities (NCEs), whereby an ANDA with a paragraph IV certification may not be submitted until four years after the NDA was approved (i.e., the NCE-1 date). Another relevant exclusivity period applies when a previously approved drug is approved for a new patient population based on new clinical studies–any ANDAs directed to that new patient population (NPP) may not be approved for a period of three years.
Because the filing and/or approval of ANDAs is tied to the FDA exclusivity periods granted to the reference listed GLP-1 drugs, the timing of related patent infringement lawsuits brought under the Hatch-Waxman Act varies as well.
For example, liraglutide was first approved in 2010 as Victoza® for treatment of diabetes and later approved in 2014 as Saxenda® for weight loss. All relevant FDA exclusivity periods for liraglutide have expired, with patent litigation against potential generic competitors starting in 2017. FDA approved the first generic drug containing liraglutide in December 2024.
As another example, semaglutide was first approved in 2017 as Ozempic® for treatment of diabetes and later approved in 2021 as Wegovy® for weight management and weight loss. The NCE period for semaglutide has expired permitting the filing of ANDAs, although the three-year NPP exclusivity is still active for Wegovy® through December 2025. Patent litigation has been initiated against at least nine generic competitors, with settlements reported in connection with the first wave of lawsuits filed in 2022. New lawsuits were filed in 2024 against additional generic competitors, which remain ongoing. FDA has not yet approved any generic versions of semaglutide, and it is unclear when any such approved generic drugs may be permitted to enter the U.S. market.
The newest GLP-1 drug, tirzepatide, was first approved in 2022 as Mounjaro® for treatment of diabetes and later approved in 2024 as Zepbound® for obesity. The NCE period for tirzepatide runs through May 13, 2027, which means generic companies may not file an ANDA seeking approval for a generic version of Mounjaro® or Zepbound® until May 13, 2026, with patent infringement lawsuits expected to occur in the following months.
Two additional areas that may be ripe for future patent-related litigation challenges involving GLP-1 drugs include patent infringement claims brought against compounding pharmacies and claims challenging whether patents are properly listed in the Orange Book for certain GLP-1 drugs.
To date, name brand manufacturers of FDA-approved GLP-1 drugs have not appeared to target compounding pharmacies with patent infringement lawsuits, choosing instead to litigate other claims against these entities, as discussed in more detail above. As those litigations wrap up, it is possible that we could see additional patent infringement claims brought against entities making and selling compounded versions of the drugs.
Starting in fall of 2023, the Federal Trade Commission (FTC) announced a new policy expressing concerns over the potential anticompetitive effect of patents that may have been improperly listed in the Orange Book. The FTC followed this announcement with several rounds of letters to name brand manufacturers (including GLP-1 manufacturers), notifying them of FTC’s claim that certain patents were improperly or inaccurately listed. Similar challenges have been raised in U.S. courts (although directed to other drug classes), with the Federal Circuit reaching a decision in Teva Branded Pharm. Prods. R&D, Inc. v. Amneal Pharms. LLC in December 2025. In that case, Amneal filed a counterclaim seeking an order to delist certain device patents from the Orange Book. The Federal Circuit affirmed the district court’s delisting order, finding the device patents were not properly listable because they did not claim a specific active ingredient and instead were only directed to components of the device. Although there are a range of different patents listed in the Orange Book for GLP-1 drugs, it is worth monitoring ongoing FTC investigations and enforcement trends to the extent these may impact future Orange Book listing challenges raised by competitors.
International Trade Commission
Section 337 of the Tariff Act of 1930 (19 U.S.C. § 1337) grants the U.S. International Trade Commission (ITC) authority to resolve complaints filed by companies alleging unfair acts in the importation of products into the U.S. Although Section 337 cases typically involve allegations of infringement of various IP rights, including patents, trade secrets and trademarks, the ITC is also empowered to address other violations, including claims based on importation of non-approved drugs and Lanham Act claims based on false advertising and false designation of origin.
In addition to moving more quickly relative to most U.S. district court litigations, ITC cases involve several unique aspects, including a domestic industry requirement whereby the complainant asserting the violation must prove that it has established (or is in the process of establishing) a domestic industry that practices the IP right through a significant investment in various activities, including plant, equipment, labor, capital and/or a substantial investment in research and development or licensing. The remedies that may be awarded for a violation are extremely effective and can include either a limited or general exclusion order, enforced by U.S. Customs and Border Protection, which effectively bar the importation of products in violation of Section 337 from entering the U.S. Limited exclusion orders are limited to only the subject articles imported by named respondents, whereas general exclusion orders are more difficult to obtain and apply generally to all subject articles, regardless of who is responsible for importation. If proven, a general exclusion order can be extremely valuable to companies who are facing competition through importation of infringing or counterfeit articles from multiple entities where the responsible party is difficult to identify or routinely changes names/addresses.
At least one approved GLP-1 manufacturer (Eli Lilly) has filed a complaint with the ITC against various online pharmacies selling compounded drugs containing tirzepatide. Eli Lilly’s claims against the online pharmacies allege importation of unapproved drug products containing tirzepatide along with misuse of the Mounjaro® trademark and false and misleading statements regarding FDA approval and equivalency to the approval Mounjaro® product. In December 2024, the Administrative Law Judge (ALJ) at the ITC issued an Initial Determination partially granting summary determination against several of the accused pharmacies on the trademark, false designation and false advertising claims. In that decision, the ALJ also recommended the ITC issue a general exclusion order banning the importation of all products containing tirzepatide. In January 2025, the ITC issued a notice stating it was not going to review the summary determination order but sought further comments on public interest and remedy. A final decision on remedy is expected in April 2025.
Future Litigation Trends
Just as the U.S. market has adapted to the increase in sales of approved GLP-1 drugs, leading to FDA-declared drug shortages and the availability of compounded versions, the litigation landscape has adjusted as well with recent decisions focusing on FDA’s decision to remove these drugs from the shortage list. Likewise, patent litigation involving GLP-1 drugs is expected to evolve as FDA exclusivity periods expire in the near future, leading to additional challenges raised by potential generic drug competitors. Given the popularity of these drugs, relevant players in the market have adapted their litigation strategies to raise new legal claims, including in additional forums with significant remedies for violation of various IP rights.