The Supreme Court declined to hear Merck's appeal on June 16, 2025. That refusal left in place a Third Circuit decision reviving the femur fracture claims of more than 500 plaintiffs dismissed on preemption grounds three years earlier, placing the docket alongside drug-warning disputes such as the Oxbryta litigation.
Eighteen years after Merck first asked the FDA for a femoral fracture warning, the litigation is back before Judge Karen M. Williams in the District of New Jersey. This article covers the alendronate label record, the federal proceedings, the preemption standard governing them, the proof an atypical fracture claim requires, and the consequences for firms holding bisphosphonate inventory.
The Alendronate Label Record and the October 2010 Bisphosphonate Warning
The FDA approved Fosamax (alendronate sodium) in 1995, and the label carried no atypical fracture warning for fifteen years. What Merck told the agency across those years, and when, is what the preemption fight turns on in In re Fosamax (Alendronate Sodium) Products Liability Litigation, 118 F.4th 322 (3d Cir. 2024).
- September 15, 2008: Merck filed a Prior Approval Supplement, a labeling change that cannot take effect until the FDA signs off, proposing Precautions and Adverse Reactions language for low-energy subtrochanteric femoral fractures. The proposed subsection, "Low-Energy Femoral Shaft Fracture," addressed atraumatic stress fractures, prodromal pain, and interruption of therapy.
- May 2009: The FDA issued a Complete Response Letter, its formal statement of what must change before approval. The agency accepted "low energy femoral shaft and subtrochanteric fractures" in Adverse Reactions but rejected the Precautions language as inadequately justified, because identification of "stress fractures" "may not be clearly related to the atypical subtrochanteric fractures that have been reported in the literature." It later added that "the term 'stress fracture' was considered and was not accepted."
- March 10, 2010: An FDA Drug Safety Communication stated that the data reviewed "have not shown a clear connection between bisphosphonate use and a risk of atypical subtrochanteric femur fractures," a statement Merck later folded into its preemption defense.
- September 14, 2010: The American Society for Bone and Mineral Research task force published its report associating long-term bisphosphonate use with atypical femoral fractures. This date, not the later label change, became the MDL's dividing line between pre-warning and post-warning claims.
- October 13, 2010: The FDA ordered a class-wide Warnings and Precautions change for every bisphosphonate approved for osteoporosis, concluding that "atypical fractures may be related to long-term … bisphosphonate use." The required language says these fractures "most commonly occur with minimal or no trauma," "may be bilateral," and are often preceded by "dull, aching thigh pain, weeks to months before a complete fracture occurs."
- January 2011: Merck adopted the FDA's language "nearly verbatim" into the Fosamax Precautions section, where it remains.
Fosamax was never recalled and remains FDA-approved for the treatment and prevention of postmenopausal osteoporosis.
How the Fosamax MDL Was Dismissed, Revived, and Dismissed Again
The Judicial Panel on Multidistrict Litigation centralized the femur fracture cases as In re Fosamax (Alendronate Sodium) Products Liability Litigation, MDL No. 2243, in the District of New Jersey on May 23, 2011, before Judge Joel A. Pisano. Centralization pools federal cases before one judge for pretrial work while each claim keeps its own trial rights, which separates it from other aggregate litigation structures.
The first bellwether tried to verdict was Glynn v. Merck Sharp & Dohme Corp., Nos. 11-5304, 08-08 (D.N.J. 2013), heard from April 8 to April 29, 2013. An earlier femur fracture case in New Jersey state court ended in a mistrial that March when the plaintiff fell ill mid-trial.
The jury returned a unanimous verdict for Merck, finding that Bernadette Glynn, first prescribed Fosamax in 2002 and injured on April 17, 2009, had not proven she sustained an atypical femoral fracture.
On June 27, 2013, Judge Pisano ruled post-trial that there was "clear evidence that the FDA would not have approved a stronger warning prior to Mrs. Glynn's fracture," so her failure-to-warn claim was preempted. In re Fosamax, 951 F. Supp. 2d 695 (D.N.J. 2013).
Merck moved to extend that holding across the docket. On August 15, 2013, the court ordered plaintiffs with pre-September 14, 2010 injuries to show cause why their claims survived, and on March 26, 2014, it entered judgment for Merck across the pre-warning inventory. The 2014 bellwether never reached a jury: in Gaynor v. Merck Sharp & Dohme Corp., Nos. 12-1492, 08-08 (D.N.J. June 17, 2014), the court granted summary judgment because Barbara Gaynor fractured in September 2011, after the label change, and the updated label was "accurate, clear, consistent" as to atypical fractures.
The appellate history then ran five rulings over eight years:
- March 22, 2017: The Third Circuit vacated the preemption judgment in In re Fosamax, 852 F.3d 268 (3d Cir. 2017), holding that whether the FDA would have rejected a stronger warning was a question for a jury.
- May 20, 2019: The Supreme Court vacated that judgment and remanded in Merck Sharp & Dohme Corp. v. Albrecht, 587 U.S. 299 (2019), holding that the preemption question "is one for a judge to decide, not a jury."
- March 23, 2022: On remand, Chief Judge Freda L. Wolfson again found the claims preempted, concluding that the FDA "would not have approved a differently worded warning about such a risk." In re Fosamax, 593 F. Supp. 3d 96 (D.N.J. 2022).
- September 20, 2024: The Third Circuit vacated a second time in In re Fosamax, 118 F.4th 322 (3d Cir. 2024), holding the claims not preempted on this record.
- June 16, 2025: The Supreme Court denied certiorari in No. 24-977, ending Merck's appeal.
Judge Williams, who took the MDL after Judge Wolfson's retirement, did not wait for that order. On April 17, 2025, following the Third Circuit's decision, she reinstated all cases not already dismissed with prejudice, reported at more than 1,000 actions, and stayed discovery. The JPML's July 1, 2026 report counts 550 actions pending out of 1,293 filed historically, with no bellwether schedule and no global femur fracture settlement on the federal docket.
What the Albrecht Preemption Standard Requires a Manufacturer to Show
Albrecht converted the "clear evidence" phrase from Wyeth v. Levine, 555 U.S. 555 (2009), into a two-condition showing. A manufacturer arguing impossibility preemption, meaning federal law made it impossible to also satisfy a state duty to warn, must establish that it "fully informed the FDA of the justifications for the warning required by state law" and that the FDA "informed the drug manufacturer that the FDA would not approve a change to the drug's label to include that warning."
Judges, not juries, decide that question, because they are better equipped to weigh the scope of an agency determination. The test is whether federal and state law "irreconcilably conflic[t]."
Two regulatory routes were open to Merck in 2008. Under 21 C.F.R. § 314.70, the changes-being-effected provision lets a manufacturer strengthen a warning on newly acquired information as soon as it files, so a company that could have used that route cannot ordinarily claim impossibility. Merck filed a Prior Approval Supplement instead, which requires sign-off first, and that choice kept the argument available.
Applying Albrecht in 2024, the Third Circuit let the first condition stand, since the district court had found Merck "clearly and fully informed the FDA of the panoply of risks associated with long-term Fosamax use." Merck failed the second. The Complete Response Letter's reference to an inadequate "justification" could reflect doubt about the underlying science, or nothing more than an objection to the terminology Merck had proposed.
The court construed that ambiguity against Merck under the presumption against preemption, repeating that the "possibility of impossibility [is] not enough." It noted that such a letter carries "no implication as to the ultimate approvability of the application," and faulted the district court for resolving the ambiguity through informal FDA communications and an agency amicus brief.
Other MDL courts moved quickly. The Northern District of Ohio applied the decision in In re Suboxone (Buprenorphine/Naloxone) Film Products Liability Litigation (2024), and Judge Jane Triche Milazzo relied on it to deny Sanofi summary judgment in In re Taxotere (Docetaxel) Products Liability Litigation (2025). Plaintiff firms now lead with 118 F.4th 322 whenever a manufacturer claims the FDA refused a stronger warning.
Evidence That Establishes an Atypical Femoral Fracture Claim
Proving the injury qualifies as an atypical femoral fracture is now both a docket-management gate and an expert report problem. The New Jersey docket control order requires each plaintiff to prove the fracture qualifies "as that phrase is defined by the Second Report of the Task Force of the American Society for Bone and Mineral Research," supported by radiology or records sufficient to evaluate it, with dismissal motions available after a fourteen-day deficiency notice.
That Second Report confines these fractures to the femoral diaphysis, from just distal to the lesser trochanter to just proximal to the supracondylar flare, and excludes femoral neck, periprosthetic, and pathological fractures. Within that location, at least four of five major features must be present, so one may be absent without defeating the definition:
- Minimal or no trauma: emergency triage notes and EMS run reports document the mechanism.
- A fracture line originating at the lateral cortex and substantially transverse: review full-length AP and lateral radiographs as images, not as report language.
- Complete through both cortices, or incomplete and confined to the lateral cortex: plain films control, with MRI where an incomplete fracture is suspected.
- Noncomminuted or minimally comminuted: the radiographs should match the operative report.
- Localized periosteal or endosteal thickening, or "beaking," of the lateral cortex: earlier films can show it developing.
Contralateral femur imaging belongs in every file, because the warning states these fractures may be bilateral and the second side may be asymptomatic. Where a treating record captures the thigh or groin ache that precedes the break, a causation expert gains contemporaneous corroboration rather than a retrospective reconstruction.
How Pharmacy Records Anchor the Duration Analysis
Duration is central because the 2010 warning ties atypical fractures to long-term use. Start dates, stop dates, drug holidays, and last-fill records shape both exposure analysis and warnings causation.
Reconstructing that sequence across a decade of treatment is where the most avoidable review failures occur, and dispensing history from every pharmacy involved is the only reliable spine for it. The Glynn plaintiff's expert worked the same way, concluding from pharmacy records that the fracture followed roughly seven years of full-dose alendronate therapy.
General Versus Specific Causation
The Glynn expert rulings set the framework the MDL still uses. On general causation, whether the drug can cause the injury at all, the court found the Bradford Hill criteria "broadly accepted in the scientific community for evaluating causation." On specific causation, whether it caused this plaintiff's injury, it admitted differential diagnosis, ruling out alternative explanations one at a time, without requiring experts to exclude every conceivable cause.
Treating physicians may describe diagnosis and treatment but were barred from giving causation opinions. That testimony requires a retained expert applying a recognized methodology, and when those retained experts fail the admissibility standard the docket can end outright, as the acetaminophen rulings show.
Practice Implications for Firms Holding Bisphosphonate Inventory
Triage starts with injury date. Claims predating the January 2011 label update sit inside the revived preemption fight, while later injuries face the label-adequacy defense that ended Gaynor.
The April 2025 reinstatement did not cure dismissals for profile-form or proof-of-use deficiencies, and pendency in an MDL does not by itself answer when a limitations clock started. Each file needs state-specific accrual review and preservation notices at intake, above all where pharmacy, radiology, and operative records must be rebuilt across years of treatment.
Defense counsel will press injury-definition, proof-of-use, and limitations defenses before any bellwether sequence forms. The Elmiron vision loss litigation shows how the same label-timing questions play out when a warning arrives late.
