Biologics are commonly used to treat active psoriatic arthritis (PsA), a condition that results when the body’s immune system affects the joints. These medications are typically monoclonal antibodies (laboratory-made antibodies) that target specific parts of the immune system to reduce inflammation. Examples of biologics for PsA include adalimumab (Humira), infliximab (Remicade), and etanercept (Enbrel).

Adalimumab belongs to a group of medications known as disease-modifying antirheumatic drugs (DMARDs). These medications help reduce disease activity and prevent joint damage and progression in PsA and other inflammatory conditions. This medication can also treat joint pain and skin symptoms associated with PsA, improving your overall quality of life.

This article will explain what kind of biologic adalimumab is, how it works, and what side effects you can expect from treatment.

What Is Adalimumab and How Does It Work?

Some biologics block the function of cytokines, specialized proteins that create inflammation and play a large role in autoimmune diseases. One cytokine involved in PsA is tumor necrosis factor alpha (TNF-alpha).

Normally, TNF-alpha helps prompt your immune system to fend off bacteria and other foreign invaders. Elevated levels of this protein can lead to excess inflammation, causing your immune system to attack your healthy tissues. TNF-alpha shows up in the fluid and membranes that surround the joints in people with PsA. It can also be found in the silvery-white scales on the skin of people with PsA.

Adalimumab is an anti-TNF biologic that attaches itself to the cytokine, preventing it from interacting with immune cells. This process helps dampen inflammation, improving PsA symptoms and joint function while preventing further damage.

In 2005, the U.S. Food and Drug Administration (FDA) approved Humira (the brand name for adalimumab) for treating adults with active PsA. Since then, this biologic has also been approved to treat many other diseases, including other types of psoriasis and arthritis:

• Plaque psoriasis — An inflammatory skin condition that causes inflamed, scaly patches of skin
• Rheumatoid arthritis — An inflammatory disease that attacks the joints
• Ankylosing spondylitis — Arthritis in the ligaments and joints of the spine, leading to pain and stiffness
• Juvenile idiopathic arthritis — The most common type of arthritis seen in children, causing joint pain and inflammation
• Hidradenitis suppurativa — A chronic skin condition that causes painful lumps to form under the skin, leading to scarring
• Inflammatory bowel disease (IBD) — Chronic inflammation in the lining of the digestive tract (e.g., Crohn’s disease and ulcerative colitis)
• Noninfectious uveitis — Inflammation of the uvea (the pigmented part of your eye)

How Is Adalimumab Taken?

Adalimumab is administered as a subcutaneous injection (under the skin). Your stomach would break down the proteins in the medication, making them ineffective, so there is no oral form.

Every other week, you’ll receive a 40-milligram dose of adalimumab through a prefilled syringe or an injection pen with a very small needle. Your doctor or rheumatologist will give you your first dose, then train you to do the injections yourself at home.

Adalimumab should be stored in your fridge. Be sure to take it out 15 to 20 minutes before injecting it so it can come to room temperature — injections can be uncomfortable if your medication is cold. You may inject adalimumab into your thigh or stomach area (at least two inches from your belly button). Rotating injection sites will help keep your skin from becoming too irritated.

Your rheumatologist may also prescribe adalimumab along with a nonbiologic DMARD to help control your PsA if needed. Examples include:

• Methotrexate (Otrexup, Rasuvo, Trexall)
• Leflunomide (Arava)
• Sulfasalazine

Combination therapy can help treat your tender joints and improve your skin symptoms as well.

What Are the Side Effects of Adalimumab?

When taking any medication to help manage your disease, the benefits must outweigh the risk of unwanted effects. One common side effect of adalimumab is an injection site reaction — redness, pain, swelling, bruising, or itching where you injected the medication. You might also get more frequent headaches, nausea, or back pain.

Because adalimumab treatment reduces your immune system’s function, you may be at a higher risk of developing infections. These can include mild infections, such as:

• Influenza (the flu)
• Sinus infections
• Upper respiratory infections, such as colds
• Urinary tract infections

Using TNF inhibitors (blockers) can also put you at a very small risk of developing serious infections such as:

• Tuberculosis — A serious lung infection spread by bacteria
• Fungal infections — Common in people who live or have lived in Ohio or areas along the Mississippi river
• Hepatitis B — A liver infection spread by the hepatitis B virus

Some infections can sit in your body for many years and become active once your immune system is impaired. Your rheumatologist will run screening tests, such as a hepatitis screening test and a Quantiferon-TB test (a simple blood test that helps to detect bacteria that cause tuberculosis) to see if you were infected before. They’ll continue to monitor you throughout your treatment to make sure the medication is effective.

Other rare, serious side effects of adalimumab include:

• New or worsening nerve conditions, such as multiple sclerosis
• Certain types of malignancies (cancer), including leukemia, lymphoma, and skin cancer
• New or worsening heart failure
• Lupus-like syndrome, an autoimmune condition that affects the skin, joints, and kidneys

Adalimumab Biosimilars

Since approving Humira in 2005, the FDA has also OK’d several biosimilars — medications that are very similar to adalimumab but may have slightly different structures or are made another way. Biosimilars make more options available, which helps lower costs.

To be approved by the FDA, a biosimilar must go through rigorous studies and clinical trials (studies in people) to show that they’re as safe and effective as the original biologic. Some biosimilars undergo additional testing to prove that they’re interchangeable — this means that a pharmacist can substitute a biosimilar for adalimumab without requiring your doctor to change your prescription. Not all biosimilars are interchangeable.

The FDA has approved several adalimumab biosimilars, and they’re set to hit the market in July 2023. These include:

• Adalimumab-adbm (Cyltezo) — The only interchangeable biosimilar approved so far
• Adalimumab-afzb (Abrilada)
• Adalimumab-atto (Amjevita)
• Adalimumab-bwwd (Hadlima)
• Adalimumab-fkjp (Hulio)
• Adalimumab-adaz (Hyrimoz)
• Adalimumab-aqvh (Yusimry)

Researchers have at least three more biosimilars in the works, offering people with PsA several treatment options. Some of these new biosimilars will come as high-concentration formulas (similar to adalimumab), so they’ll require fewer injections.

If you’re interested in learning more about adalimumab and its biosimilars and whether they may be the right treatment option for you, talk to your rheumatologist.

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Are you currently taking adalimumab for your PsA? Have you and your doctor discussed biosimilars? Share your experience in the comments below, or start a conversation by posting on your Activities page.