Updated
The dosing and administration of Xeljanz is one of the central issues in the Xeljanz lawsuits that have been filed against the drug’s manufacturer, Pfizer. The risks of developing the severe side effects of Xeljanz, which include pulmonary embolism, liver damage, and cancer, seem to increase dramatically at higher doses.
However, these risks were not adequately mentioned on the warning label for Xeljanz. It was only in July of 2019 that the FDA ordered Pfizer to include a black box warning on the drug, which many believe is still inadequate. As a result, Xeljanz lawsuits have been filed to recover compensation for losses and injuries suffered by victims.
The defective drug attorneys at the Shouse Law Office can help victims file a Xeljanz lawsuit and pursue the compensation they need before the statute of limitations has run its course. In this article they delve into:
- 1. What is Xeljanz?
- 2. Side effects of Xeljanz
- 3. Administration of Xeljanz
- 4. High Xeljanz doses can lead to severe side effects
- 5. The role of administration and dosing in Xeljanz lawsuits

1. What is Xeljanz?
Xeljanz is the brand name that Pfizer gave to its drug for rheumatoid arthritis, tofacitinib.
Pfizer obtained approval by the U.S. Food and Drug Administration (FDA) for Xeljanz to treat:
- Rheumatoid arthritis in November, 2012,1
- Psoriatic arthritis in December, 2017,2 and
- Ulcerative colitis in May, 2018.3
The drug works by inhibiting the workings of Janus kinase, or JAK, enzymes. These enzymes are among the biological processes that are responsible for the growth of new cells. When JAK enzymes go wrong, they can produce too many cells. In some cases, this can lead to tissue buildup in a patient’s joints. That tissue can damage the cartilage and bone structure that makes the joint work. Worse, the body’s immune system can see the new tissue as a foreign body and attack it. This leads to inflammation and pain in the joint and creates the medical condition known as rheumatoid arthritis.
2. Side effects of Xeljanz
However, Xeljanz has been linked to a handful of side effects.
Some of the most common side effects include:
- Sore throat,
- Fatigue,
- Symptoms of the common cold,
- Sinus infections,
- Infections in the upper respiratory tract,
- High blood pressure,
- Neutropenia, or a low white blood cell count,
- Runny nose or nasal congestion,
- Headaches, and
- Diarrhea.
Some of the severe side effects can be life-threatening or debilitating:
- Cancer and other malignant growth,
- Liver damage,
- Blood clotting in the lungs, and
- Pulmonary embolism.
3. Administration of Xeljanz
How Xeljanz is administered to patients has become a key component in the legal claims against Pfizer.
Xeljanz is administered orally, in the form of a pill. This style of administration was one of the things that made it so popular when it was first released: Earlier treatments for rheumatoid arthritis had to be administered with an injection directly into the joint.
However, Xeljanz can come in two distinct pill forms:
- Xeljanz, which comes in pills of 5 milligrams each, and
- Xeljanz XR, which comes in pills of 11 milligrams each.
The XR in Xeljanz XR stands for “extended-release.”
When taking the 5-milligram pill of Xeljanz, patients are often instructed to take one pill at a time, at two different times during the day. Patients taking certain other drugs or who have had liver or kidney problems only take one pill of Xeljanz per day.4
When taking the 11-milligram Xeljanz XR pill, patients are supposed to only take one per day: The composition of the pill delays the release of the active ingredients in the drug, extending it throughout the course of the day. People who are taking certain other medications or who have kidney or liver problems are supposed to switch from Xeljanz XR back to the basic administration of Xeljanz so they can lower their dose to 5 total milligrams per day.5
However, patients with moderate to severe ulcerative colitis receive higher doses of Xeljanz to treat their condition. In the absence of other medications or evidence or a history of liver or kidney problems, people taking Xeljanz for their ulcerative colitis take 10 milligrams of Xeljanz twice every day.6
Because higher doses mean it would make the company more money in Xeljanz sales, Pfizer has been itching to get Xeljanz prescribed in its higher, ulcerative colitis doses to people suffering from rheumatoid or psoriatic arthritis.
4. High Xeljanz doses can lead to severe side effects
In one of its FDA-mandated post-marketing clinical trials, Pfizer gave some of its arthritic patients the higher, twice daily 10 milligram doses. The results were so problematic that Pfizer had to step in and shift the study participants into lower doses.
That post-marketing trial, Study A3921133, covered 4,000 participants and began on March 14, 2014.7 It was mandated by the FDA to test how Xeljanz compared to a tumor necrosis factor inhibitor drug in treating rheumatoid arthritis.8 One of the focal points of the trial was on whether Xeljanz posed a risk to people who have heart problems in the past: Participants in the post-marketing trial had to be over the age of 50 and had to have at least one cardiovascular risk point.
What Study A3921133 found, though, was that high doses of Xeljanz created a disturbingly high risk of developing a blood clot in the lungs, which could cause a pulmonary embolism.
Even before the study was complete, the Rheumatology Data Safety Monitoring Board notified Pfizer of data that showed study participants taking the 10-milligram dose of Xeljanz twice every day were having pulmonary embolisms at a rate more than five times higher than those in the comparator arm who were taking the tumor necrosis factor inhibitor drug.9 Participants getting high doses of Xeljanz in Study A3921133 were three times as likely as other Xeljanz recipients in the study and other clinical trials for the drug.10
On February 19, 2019, with more than a year left in the study, Pfizer lowered the dosage of the study participants receiving 10 milligrams of Xeljanz twice every day. On February 25, the FDA issued a safety announcement to warn doctors and patients about the risks of blood clots entering the lungs and pulmonary embolisms at the higher doses.11 Only after the FDA made the safety announcement did Pfizer issue a press release admitting to the problems in its study.12
5. The role of administration and dosing in Xeljanz lawsuits
The administration and dosing of Xeljanz play a huge role in the resulting lawsuits that have been filed against Pfizer because they illustrate Pfizer’s interest in making money dominating patient safety. They also show that people taking high doses of Xeljanz to treat their arthritis or their ulcerative colitis could be at risk of a potentially fatal blood clot in their lungs and a pulmonary embolism, all without being warned by Pfizer.
Drug companies like Pfizer have a legal obligation to issue warnings about the side effects and adverse events that their drugs can cause. However, disclosing these dangers can cut into the drug’s sales, so pharmaceutical companies often do what they can to dodge their responsibilities. Doctors and patients suffer because they are left unable to make informed prescriptions or medical decisions.
Xeljanz lawsuits claim that the warning label that Pfizer has used for Xeljanz failed to adequately warn people about the risks of taking the drug, and argue that this amounted to a breach of its legal duty to disclose those risks. The lawsuits demand compensation for a victim’s losses and injuries, including:
- Medical expenses, both in the past and in the future,
- Pain and suffering,
- Wages lost,
- Reduced ability to earn an income in the future, and
- Loss of companionship suffered by the victim’s family.
They also claim that Pfizer should pay punitive damages for its decision not to warn doctors and patients of the risks of taking Xeljanz in high doses.
Already, there are hundreds of Xeljanz lawsuits that seek to hold Pfizer accountable. Because they involve victims who were hurt in similar ways by the same course of conduct, these Xeljanz lawsuits are ripe for consolidation into a multidistrict litigation (MDL). MDLs streamline the legal process by combining hundreds or even thousands of lawsuits into one federal court for the pretrial procedures, allowing victims and their lawyers to share evidence they have gathered.
While an MDL has not been created for Xeljanz lawsuits just yet, it seems likely that one will be created in the near future.
References:
- FDA Approval Letter for Xeljanz (November 6, 2012).
- Press Release, “Pfizer Announces FDA Approval of Xeljanz® (tofacitinib) and Xeljanz® XR for the Treatment of Active Psoriatic Arthritis,” Pfizer, (December 14, 2017).
- FDA Approval Letter for Xeljanz to Treat Ulcerative Colitis (May 30, 2018).
- See Xeljanz Warning Label (May 2018).
- See note 4.
- See note 4.
- ClinicalTrials.gov Identifier No. NCT02092467, “Safety Study Of Tofacitinib Versus Tumor Necrosis Factor (TNF) Inhibitor In Subjects With Rheumatoid Arthritis.”
- See Press Release, “Increased risk of pulmonary embolism and mortality in rheumatoidarthritis patients receiving 10mg twice daily in a clinical trial,” Pfizer (March 26, 2019).
- See note 8.
- See note 8.
- FDA Drug Safety Communication, “Safety trial finds risk of blood clots in the lungs and death with higher dose of tofacitinib (Xeljanz, Xeljanz XR) in rheumatoid arthritis patients; FDA to investigate,” (February 25, 2019).
- Press Release, “Communication of new safety information for XELJANZ (tofacitinib),” Pfizer (February 28, 2019); Allison Prang, “FDA Requires Box Warnings for Pfizer Drug Xeljanz Patients taking 10-milligram dose twice a day could experience a higher risk of blood clots or death,” Wall Street Journal (July 26, 2019).