Rituxan is a biologic drug approved by the approved by the U.S. Food and Drug Administration (FDA) in 2006 to treat rheumatoid arthritis (RA). Its generic name is rituximab.

People with RA who haven’t responded to other types of treatment may use Rituxan in combination with the drug methotrexate.

Rituxan is a colorless liquid given by infusion. It’s a genetically engineered antibody that targets the B cells involved in RA inflammation. The FDA has also approved Rituxan for non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, and granulomatosis with polyangiitis.

Both rituximab and methotrexate, an immune-system suppressor, were initially developed and used as anticancer drugs. Rituxan is produced by Genentech. In Europe, it’s marketed as MabThera.

The FDA has approved treatment with Rituxan and methotrexate:

  • if you have moderate to severe RA
  • if you haven’t responded positively to treatment with blocking agents for tumor necrosis factor (TNF)

The FDA advises that Rituxan should be used during pregnancy only when the potential benefit to the mother outweighs any potential risk to the unborn child. The safety of Rituxan use with children or nursing mothers isn’t yet established.

The FDA recommends against the use of Rituxan for people with RA who haven’t been treated with one or more blocking agents for TNF.

Rituxan is also not recommended for people who have had hepatitis B or carry the virus, because Rituxan could reactivate hepatitis B.

The effectiveness of rituximab in a research study was first reported in 1998. Other clinical trials followed.

The FDA’s approval of Rituxan use for RA was based on three double-blind studies that compared rituximab and methotrexate treatment with a placebo and methotrexate.

One of the research studies was a two-year randomized study called REFLEX (Randomized Evaluation of Long‐Term Efficacy of Rituximab in RA). Effectiveness was measured using the American College of Rheumatology (ACR) evaluation of improvement in joint tenderness and swelling.

The people who received rituximab had two infusions, two weeks apart. After 24 weeks, REFLEX found that:

  • 51 percent of people treated with rituximab versus 18 percent treated with a placebo showed an improvement of ACR20
  • 27 percent of people treated with rituximab versus 5 percent of people treated with a placebo showed an improvement of ACR50
  • 12 percent of people treated with rituximab versus 1 percent of people treated with a placebo showed an improvement of ACR70

The ACR numbers here refer to improvement from the baseline RA symptoms.

The people treated with rituximab had significant improvement in other symptoms such as fatigue, disability, and quality of life. X-rays also showed a trend toward less joint damage.

Some people in the study experienced side effects, but these were of mild to moderate severity.

Many other studies since 2006 have found similar benefits to treatment with rituximab and methotrexate.

The mechanism for rituximab’s effectiveness in treating RA and other diseases isn’t fully understood. It’s thought that rituximab antibodies target a molecule (CD20) on the surface of certain B cells that are associated with the RA inflammation process. These B cells are thought to be involved with producing rheumatoid factor (RF) and other substances associated with inflammation.

Rituximab is observed to cause a temporary but thorough depletion of B cells in the blood and a partial depletion in the bone marrow and tissue. But these B cells regenerate in six to nine months. This may require continued rituximab infusion treatment.

Research is ongoing to probe how rituximab and B cells work in RA.

Rituxan is given by a drip into a vein (intravenous infusion, or IV) in a hospital setting. The dosage is two 1,000-milligram (mg) infusions separated by two weeks. The Rituxan infusion isn’t painful, but you may have an allergic-type reaction to the drug.

Your doctor will check out your general health before giving the treatment and monitor you during the infusion.

Half an hour before the Rituxan infusion starts, you’ll be given an infusion of 100 mg of methylprednisolone or a similar steroid and possibly also an antihistamine and acetaminophen (Tylenol). This is recommended to help reduce any possible reaction to the infusion.

Your first infusion will start slowly at a rate of 50 mg per hour, and the doctor will keep checking your vital signs to make sure you’re not having any adverse reaction to the infusion.

The first infusion process may take about 4 hours and 15 minutes. Flushing the bag with a solution to make sure you get the full dose of Rituxan takes another 15 minutes.

Your second infusion treatment should take about one hour less.

In clinical trials of Rituxan for RA, about 18 percent of people had side effects. The most common side effects, experienced during and 24 hours after infusion, include:

  • mild throat tightening
  • flu-like symptoms
  • rash
  • itchiness
  • dizziness
  • back pain
  • upset stomach
  • nausea
  • sweating
  • muscle stiffness
  • nervousness
  • numbness

Usually the steroid injection and antihistamine that you receive before the infusion lessen the severity of these side effects.

If you have more serious symptoms, call your doctor. These may include:

Call your doctor right away if you experience vision changes, confusion, or loss of balance. Serious reactions to Rituxan are rare.

Rituxan (generic rituximab) has been FDA-approved for RA treatment since 2006. About 1 in 3 people treated for RA don’t respond adequately to other biologic therapies. So Rituxan provides a possible alternative. As of 2011, more than 100,000 people with RA across the globe had received rituximab.

If you’re a candidate for Rituxan, read up on its effectiveness so you can make an informed decision. You’ll have to balance the benefits and potential risks versus other treatments (such as minocyline or new drugs in development). Discuss your treatment plan options with your doctor.