DMARDs: Disease-Modifying Antirheumatic Drugs

What are DMARDs?

DMARDs, or Disease-Modifying Antirheumatic Drugs, are a group of medications used to treat inflammatory rheumatic diseases. Unlike conventional painkillers or corticosteroids, DMARDs do not simply relieve symptoms. Instead, they target the underlying immune processes that drive inflammation and joint destruction, thereby slowing or halting disease progression.

Indications

DMARDs are primarily used in the treatment of:

• Rheumatoid arthritis (chronic inflammatory joint disease)
• Psoriatic arthritis (joint inflammation associated with psoriasis)
• Ankylosing spondylitis (axial spondyloarthritis)
• Systemic lupus erythematosus (SLE)
• Juvenile idiopathic arthritis
• Other inflammatory connective tissue disorders

Classification: Types of DMARDs

Conventional Synthetic DMARDs (csDMARDs)

These are chemically synthesized compounds that have been used in rheumatology for decades. Key representatives include:

• Methotrexate (MTX): Often the first-line treatment for rheumatoid arthritis; inhibits the proliferation of activated immune cells.
• Hydroxychloroquine: Originally an antimalarial drug, now used for milder rheumatic conditions and SLE.
• Sulfasalazine: Has anti-inflammatory properties and is used in arthritis and inflammatory bowel disease.
• Leflunomide: Inhibits immune cell proliferation and is used as an alternative to methotrexate.

Biological DMARDs (bDMARDs)

Biologics are biotechnologically produced protein molecules that specifically target inflammatory mediators or receptors in the immune system. Key subgroups include:

• TNF-alpha inhibitors (e.g., etanercept, adalimumab, infliximab): Block the pro-inflammatory cytokine TNF-alpha.
• IL-6 inhibitors (e.g., tocilizumab): Inhibit the action of interleukin-6, another key inflammatory mediator.
• IL-17 and IL-23 inhibitors: Particularly relevant for psoriatic arthritis and spondylitis.
• B-cell depleting agents (e.g., rituximab): Reduce the number of B cells in the immune system.
• T-cell co-stimulation inhibitors (e.g., abatacept): Suppress the activation of T cells.

Biosimilars

Biosimilars are follow-on versions of approved biologics, available after the expiry of the original patent. They are considered comparable in efficacy and safety to the reference product and are often more cost-effective.

Targeted Synthetic DMARDs (tsDMARDs)

This newer class includes orally administered small molecules that block specific intracellular signaling pathways. The most prominent are JAK inhibitors (Janus kinase inhibitors, e.g., tofacitinib, baricitinib, upadacitinib), which interrupt signaling cascades inside immune cells.

Mechanism of Action

What all DMARDs have in common is that they actively interfere with the overactive immune response responsible for joint and tissue damage, rather than simply masking pain. Depending on the drug class, this occurs through:

• Inhibition of immune cell proliferation and activation
• Blockade of inflammatory cytokines such as TNF-alpha, IL-6, and IL-17
• Interruption of intracellular signaling pathways (JAK-STAT pathway)
• Reduction of specific immune cell populations (B cells or T cells)

Dosage and Administration

Dosage and route of administration vary considerably depending on the specific drug. Conventional DMARDs such as methotrexate are typically taken once weekly, either orally (tablet) or subcutaneously (injection). Biologics are generally administered subcutaneously (self-injected at home) or intravenously (as an infusion at a clinic or doctor's office). JAK inhibitors are available as daily oral tablets. Treatment should always be supervised by a specialist in rheumatology.

Side Effects and Risks

Because DMARDs modulate the immune system, they can increase susceptibility to infections. Other potential side effects depend on the specific drug:

• Methotrexate: Nausea, elevated liver enzymes, increased infection risk; folic acid supplementation is recommended.
• Hydroxychloroquine: Visual disturbances with long-term use (regular ophthalmological monitoring required).
• TNF inhibitors: Increased risk of bacterial infections and reactivation of tuberculosis; screening before starting therapy is mandatory.
• JAK inhibitors: Increased risk of herpes zoster; potential cardiovascular risks in certain patient groups.

Regular monitoring (blood count, liver and kidney function tests) is essential during DMARD therapy.

Treatment Context and Therapeutic Goals

According to guidelines from the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR), DMARD therapy in rheumatoid arthritis should be initiated as early as possible to prevent irreversible joint damage. The primary treatment goal is remission (complete absence of inflammatory activity) or at least low disease activity, following the treat-to-target principle. Therapy is individualized and escalated or combined as needed.

References

1. Smolen JS et al. - EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2022 update. Annals of the Rheumatic Diseases, 2023.
2. Fraenkel L et al. - 2021 American College of Rheumatology Guideline for the Treatment of Rheumatoid Arthritis. Arthritis and Rheumatology, 2021.
3. Favalli EG et al. - The Evolution of Treatment Strategies in Rheumatoid Arthritis: From DMARDs to Biologics and Beyond. Journal of Clinical Medicine, 2019.