Ankylosing spondylitis is a type of arthritis that inflames joints of the spine and leaves your back stiff and painful. If nonsteroidal anti-inflammatory drugs (NSAIDs) aren't enough to relieve your pain and inflammation, the next treatment you try could be a DMARD, or disease-modifying antirheumatic drug.
How Do DMARDs for Ankylosing Spondylitis Work?
In ankylosing spondylitis, your immune system overreacts and produces inflammation. That inflammation causes pain and a loss of movement in your spine.
DMARDs calm your immune system to bring down inflammation and relieve pain. They're called "disease-modifying" because unlike NSAIDs, these medicines slow the disease and help to prevent joint damage.
What Types of DMARDs Treat Ankylosing Spondylitis?
DMARDs used to treat ankylosing spondylitis can be split into biologics and traditional DMARDS.
Biologics target specific proteins of your immune system that cause inflammation. Each biologic drug blocks a different protein.
You either give these medicines to yourself as an injection or visit your doctor's office or clinic for an infusion. The dosage and schedule are different for each of these medicines and may change over the course of your treatment.
TNF inhibitors. Tumor necrosis factor (TNF) inhibitors were the first biologic drugs approved to treat ankylosing spondylitis. They block a protein called tumor necrosis factor, which causes inflammation and symptoms of ankylosing spondylitis.
TNF inhibitors treat arthritis in both the joints and spine. They also help with conditions that affect some people with ankylosing spondylitis, such as:
- Eye inflammation called uveitis
- Inflammatory bowel disease (IBD) – Crohn's disease and ulcerative colitis
Treatment guidelines recommend TNF inhibitors only after you've tried two different NSAIDs but they didn't relieve your symptoms.
Five TNF inhibitors are approved to treat ankylosing spondylitis:
There isn't any evidence that one of these drugs works better than the others. But because each one works in a slightly different way, if the first TNF inhibitor you try doesn't help, your doctor might switch you to another drug in this group. Up to 40% of people who switch medicines will respond to the second drug they try.
Because Remicade is more likely to cause infections like tuberculosis (TB) than other TNF inhibitors, your doctor might not choose this drug for you if you are at high risk for infection.
IL-17 inhibitors. IL-17 inhibitors block interleukin-17, which also causes inflammation. Because they work differently, IL-17 inhibitors could help people who didn't find relief from TNF inhibitors.
The two IL-17 inhibitors approved to treat ankylosing spondylitis are:
Your doctor might recommend one of these medicines if you have active ankylosing spondylitis and you can't take a TNF inhibitor because of heart failure or multiple sclerosis, or if you tried a TNF inhibitor and it didn't help you.
JAK inhibitors. Janus kinase (JAK) inhibitors are a newer kind of DMARD. They're different from the biologic drugs. They target a group of enzymes that are involved in producing inflammation.
Tofacitinib (Xeljanz, Xeljanz XR) and upadacitinib (Rinvoq) are approved to treat ankylosing spondylitis. They come as a pill, which you may prefer if you don't like to get injections.
Biosimilars. Biosimilars are medicines that work like biologic drugs but are less expensive. Inflectra/CT-P13 was the first biosimilar approved for ankylosing spondylitis. It works like the TNF inhibitor Remicade. Adalimumab-atto is the biosimilar version of Humira.
Treatment guidelines for ankylosing spondylitis don't recommend switching from a TNF inhibitor to its biosimilar. Even though the drugs are similar, changing drugs could affect your outcome. And if you didn't improve on a TNF inhibitor, its biosimilar probably won't help you, either.
Methotrexate (Rheumatrex, Trexall, others) and sulfasalazine (Azulfidine) are traditional DMARDs. These medicines are mainly for peripheral arthritis, which means the pain and inflammation are in your arms, hips, knees, or ankles. They don't work well for arthritis in the spine. You might get one of these medicines if you can't take a TNF inhibitor.
Methotrexate is a cancer drug that also treats inflammatory forms of arthritis, but at a lower dose. In ankylosing spondylitis, the drug reduces inflammation and helps to prevent joint damage. Methotrexate comes as a pill or shot.
Sulfasalazine works best for peripheral arthritis symptoms or if you can't take a TNF inhibitor. It's usually not for symptoms in the spine. It also treats IBD. You take sulfasalazine as a pill. Your doctor might start you on a low dose and slowly increase it to reduce side effects.
How Does Your Doctor Choose a DMARD for You?
Your doctor will recommend a DMARD based on factors like:
- How severe your symptoms are
- Which medicines you've tried before and how well they worked
- What side effects the medicine causes
Treatment of Non-Radiographic Ankylosing Spondylitis
Non-radiographic ankylosing spondylitis means that you don't have signs of joint damage on X-rays. You might call it the early stage of the disease.
Guidelines also recommend TNF inhibitors for this early stage of the disease. The evidence on IL-17 inhibitors and JAK inhibitors for non-radiographic ankylosing spondylitis isn't as strong.
What to Expect
DMARDs can be helpful for relieving pain and improving movement, but they work differently for everyone. If the DMARD you try doesn't help right away, be patient. It can take a few weeks for these medicines to start working.
You may need to stay on a TNF inhibitor, even if you go into remission or your symptoms improve. Stopping these medicines could cause you to relapse.
What Side Effects Can DMARDs for Ankylosing Spondylitis Cause?
DMARDs can cause side effects. Some are mild, others serious. Talk to your doctor about the risks before you start taking one of these medicines, and ask what to do if you do have side effects.
Biologic drugs work by dialing down your immune system, which could make it harder for your body to fight infections. It's important to get all of your recommended vaccines before you start on one of these medicines. If you do get an infection and it's serious, you may need to stop taking the biologic.
Get tested for tuberculosis (TB) before you take a TNF inhibitor. These medicines could reactivate a TB infection if you've been infected. If you do test positive for TB, you'll get treatment before you start on one of these medicines.
TNF inhibitors might also slightly increase the risk for some cancers, including lymphoma and skin cancers. Your doctor might monitor you for cancer while you take one of these medicines.
IL-17 inhibitors could trigger IBD or make the disease worse in people who already have it.
Other possible side effects with the biologics are:
- Reactions from the injection
Methotrexate can cause side effects like:
- Upset stomach
- Mouth sores
- Infections, fever, bruising, or bleeding from low blood cell counts
Taking folic acid or folinic acid lowers your risk for these side effects.
You'll need to have kidney and liver tests every 1 to 3 months while taking methotrexate because the drug can damage these organs. Rarely, it can cause lung problems. Methotrexate is not recommended during pregnancy because it could harm your growing baby.
Sulfasalazine can have side effects like:
- Nausea or vomiting
- Sensitivity to sunlight
- Changes in blood cell counts
You may need to have blood tests while you take sulfasalazine to monitor your blood cell counts. This medicine can turn your tears, sweat, and pee a yellow-orange color. It's not dangerous, but it could stain your clothes.