IL-23 and IL/23 Antagonists Print Page

What are IL-23 and IL-12/23 Antagonists?

  • IL-23 and IL-12/23 Antagonists are in a class of medications called disease modifying antirheumatic drugs (DMARDs)
  • DMARDs are a slow acting but effective treatment for rheumatoid arthritis and other form of inflammatory arthritis.
  • These IL antagonists are biologic DMARDs, a newer class of DMARDs which have been in existence for since approximately the year 2000.
  • Their use is primarily in the treatment of psoriatic arthritis.

What is the typical dose for IL-23 and IL-12/23 Antagonists?

  • Ustekinumab (Stelara) is an IL-12/23 antagonist given as an injection under the skin (subcutaneous) every 12 weeks.
    • The dose of Ustekinumab depends on your weight; 45mg injections, or 90mg injections for those weighing greater than 100 kg.
  • Guselkumab (Tremfya) is an IL-23 antagonist given as injection under the skin (subcutaneous) every 8 weeks.  The dose is 100 mg.

How do IL-23 and IL-12/23 Antagonists work?

  • These specific biologics are a relatively new DMARD, with Ustekinumab approved for use in Canada for psoriatic arthritis in 2014, and Tremfya in 2020.
  • They work by blocking the effect of the immune protein: IL12/23.  By doing this, it can help decrease the body’s inflammatory response, thereby decreasing joint and skin inflammation.
  • There is no clear data yet to suggest these are better medications than any other new medications for inflammatory arthritis called biologics.

If I start ustekinumab or guselkumab, can I stop my other DMARDs?

  • Some rheumatologists will suggest you continue with at least methotrexate, assuming you have not had side effects, in addition to ustekinumab or guselkumab.
  • Keep in mind: In most instances, your rheumatologist has recommended you start a new medication because your inflammatory arthritis has not been well controlled. It is important to try to control your disease as best as possible first, which may mean continuing all DMARDs for some time, before trying to decrease them.

What are the possible side effects of IL-12/23 and IL-23 antagonists?

  • While generally well tolerated, they can cause:
    • Upset Stomach
    • Muscle Aches
    • Increase your risk for serious infections, including tuberculosis
    • Possible increased risk for certain types of cancer

What can I do to decrease my risk of side effects?

  • Stop the biologic any time you have a fever. It is usually safe to resume it once you are better.
  • Fevers and other severe illness should not be ignored and discussed with your doctor.
  • Your doctor will have you perform tests for tuberculosis exposure prior to starting ustekinumab or guselkumab.
  • Follow your rheumatologist’s instructions for monitoring bloodwork regularly.
  • Let your physician know if you have any changes in your medical history.

What should I do if I miss my dose?

  • It depends on how much time has passed.  If it is only a few days, it should not be a concern.  If a few weeks have passed, please check with your rheumatologist before you take your next dose.

How can I safely stop ustekinumab or guselkumab?

  • It is safe to just stop either of these medications; you do not need to slowly reduce the dose. However, keep in mind, if you were gaining any benefit, it will usually take a few weeks to lose it.