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Rituximab (Rituxan)

A biologic medication that depletes B cells, used for neuromyelitis optica (NMO), MOG antibody disease, and myasthenia gravis - especially MuSK-antibody-positive MG.

Drug Class: Biologics

7 min read

Rituximab (brand name Rituxan, with several biosimilars such as Truxima and Ruxience) is a monoclonal antibody that depletes B cells - the immune cells that make antibodies. By lowering B-cell counts, it dampens the autoimmune response driving certain neuro-ophthalmic conditions. It is given as an IV infusion, typically every 6 months.

Key Takeaways

  • Depletes B cells to reduce autoantibody production
  • Used off-label in the U.S. for NMOSD, MOGAD, and myasthenia gravis
  • May be considered early in selected NMOSD and MuSK-antibody-positive myasthenia gravis cases, depending on specialist judgment and available approved options
  • Often second-line for refractory AChR-positive myasthenia gravis, MOGAD, and other autoimmune eye disease
  • IV infusion, usually every 6 months after an induction
  • FDA boxed warnings - see below
  • Long-term immunosuppression; infection risk, infusion reactions, and hepatitis B reactivation are the main safety issues

Common Uses in Neuro-Ophthalmology

The U.S. Rituxan label includes indications such as non-Hodgkin lymphoma, chronic lymphocytic leukemia, rheumatoid arthritis, granulomatosis with polyangiitis/microscopic polyangiitis, and pemphigus vulgaris. The neuro-ophthalmic uses below are off-label in the United States and are chosen by specialists when the expected benefit outweighs risks and alternatives.

  • Neuromyelitis optica (NMO/NMOSD) - off-label relapse prevention in some centers; FDA-approved options for AQP4-positive NMOSD include complement inhibitors, IL-6 pathway therapy, and other B-cell-directed therapy
  • MOG antibody disease (MOGAD) - off-label, usually for relapsing or severe disease
  • Myasthenia gravis - off-label; considered early by some specialists for MuSK-antibody-positive MG and more often reserved for refractory AChR-positive MG
  • Refractory thyroid eye disease - off-label
  • Other steroid-dependent autoimmune eye disease (ocular inflammatory disease, IgG4-related disease) in selected patients - off-label

How It Works

  • Targets the CD20 protein on mature B cells
  • Destroys circulating B cells within days
  • B cells eventually regenerate over 6-12 months, at which point symptoms may return and re-dosing is often needed
  • By reducing B cells, rituximab lowers production of autoantibodies and changes how immune cells interact

Administration

  • IV infusion at an infusion center
  • Induction: commonly two infusions 2 weeks apart, or four weekly doses (depending on indication and local protocol)
  • Maintenance: usually one infusion every 6 months, sometimes guided by CD19/CD20 counts
  • Premedication with corticosteroids, acetaminophen, and an antihistamine reduces infusion reactions
  • First infusion is the slowest (several hours); subsequent ones are often faster

FDA Boxed Warnings

Call 911 during or after an infusion for trouble breathing, throat/tongue swelling, fainting, severe chest pain, or rapidly worsening weakness/confusion.

Side Effects

Infusion Reactions

  • Fever, chills, flushing, rash
  • Low blood pressure, shortness of breath
  • Most common with the first infusion; usually managed with premedication and by slowing the infusion

Infection Risk

  • Increased susceptibility to bacterial, viral, and opportunistic infections
  • Hepatitis B screening is required before starting - active or past infection can reactivate
  • Avoid live vaccines while on rituximab
  • Get flu, COVID, and pneumonia vaccines before starting when possible
  • Report any fever or illness promptly

Less Common but Serious

  • Low immunoglobulin levels (hypogammaglobulinemia) with long-term use
  • Late neutropenia (weeks to months after infusion)
  • Progressive multifocal leukoencephalopathy (PML) - extremely rare but devastating
  • Cardiac events and severe infusion reactions

Before Starting

  • Hepatitis B screening (HBsAg and anti-HBc)
  • Hepatitis C and HIV screening in most patients
  • Tuberculosis screening
  • Baseline immunoglobulin levels (IgG, IgM, IgA) and CD19/CD20 count
  • Update routine vaccines and any needed live vaccines at least 4 weeks before starting
  • Pregnancy testing and contraception planning (see below)

Pregnancy and contraception

Rituximab crosses the placenta and can deplete B cells in the fetus, and long-term pregnancy data are limited. Decisions are individualized - some neuro-immunologic conditions need ongoing treatment during pregnancy.

  • Tell your doctor if you are pregnant, planning pregnancy, or breastfeeding before starting
  • Use effective contraception during treatment and for at least 12 months after the last infusion
  • If pregnancy is planned, discuss timing with your neuro-ophthalmology or rheumatology team - sometimes infusions are adjusted around conception
  • Live vaccines should be avoided in infants exposed to rituximab in utero until B-cell recovery is confirmed
  • Breastfeeding decisions are individualized. The manufacturer recommends avoiding breastfeeding during treatment and for 6 months after the last dose, while LactMed notes very low milk transfer and that some specialty guidelines consider rituximab compatible with breastfeeding. Coordinate with the prescribing specialist and pediatrician, especially if the baby was exposed during pregnancy.

Monitoring

  • B-cell counts (CD19/CD20) to guide re-dosing
  • Immunoglobulin levels (IgG, IgM) - low levels may mean more infections and sometimes need IVIG support
  • Complete blood count for late neutropenia
  • Signs of infection, especially respiratory and skin
  • Response to treatment (relapse rate, symptom control, visual outcomes)

How Long to Treat

  • Long-term for relapsing conditions such as NMO and MOGAD
  • Duration is individualized; some patients continue for many years
  • Stopping rituximab often risks relapse - any break should be planned with your specialist and monitored with CD19/CD20 counts

Frequently Asked Questions

How is rituximab different from eculizumab or satralizumab?

Rituximab targets B cells broadly and is used off-label for NMOSD in the U.S. FDA-approved NMOSD drugs such as eculizumab and ravulizumab (C5 complement inhibitors), inebilizumab (CD19 B-cell depletion), and satralizumab (IL-6 receptor blockade) target different parts of the immune pathway. Choice depends on antibody status, relapse severity, comorbidities, pregnancy plans, vaccination status, insurance coverage, and prior response.

Will I need this forever?

Not necessarily, but in relapsing diseases like NMO it is often continued for many years because relapses cause cumulative neurologic damage. Your team will re-evaluate periodically.

What if I get sick during treatment?

Call your prescriber the same day for fever, new cough, burning with urination, severe headache, or any skin rash. Do not assume antibiotics alone are safe without review; some infections need urgent evaluation.

Can I get vaccines while on rituximab?

Live vaccines (MMR, varicella, yellow fever, nasal flu) must be avoided. Inactivated vaccines (standard flu shot, COVID, pneumonia) are safe, but their effectiveness may be reduced. Timing matters - ask your team about vaccinating before your next infusion or during B-cell recovery.

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