Rheumatoid arthritis (RA) is an autoimmune condition where the immune system mistakenly targets the joints, causing inflammation and pain. For moderate to severe RA, biologics are an effective treatment option that targets specific components of the immune system driving the disease. Unlike broader immunosuppressants, biologics offer a more focused approach to managing RA.
Mechanisms of Action in Biologics
Biologic therapies represent a targeted approach to managing rheumatoid arthritis. Unlike traditional disease-modifying antirheumatic drugs (DMARDs) that have a broad effect, biologics are engineered to interfere with specific pathways of the inflammatory process. Their precision allows them to modulate the immune response rather than suppressing it entirely, which distinguishes them from conventional DMARDs and steroids.
The development of these therapies stemmed from the discovery that the inflamed joints of people with RA contain high levels of specific chemicals, such as cytokines, that promote inflammation. These complex molecules are derived from living organisms and are designed to block these chemical messengers. By doing so, biologics interrupt the signaling cascades that lead to joint swelling and other symptoms, helping to reduce disease activity and slow joint damage.
Classes of Biologic Drugs for Rheumatoid Arthritis
A primary class of biologics is the Tumor Necrosis Factor (TNF) inhibitors. TNF is a protein that plays a part in promoting inflammation, and by blocking it, these drugs can reduce the inflammatory process in the joints. Examples of TNF inhibitors include adalimumab (Humira) and etanercept (Enbrel), which are widely used to help prevent long-term joint damage.
Another category of biologics targets interleukins, which are cytokines that act as messengers between cells and contribute to the inflammatory response. Interleukin-6 (IL-6) inhibitors, such as tocilizumab (Actemra), work by blocking the IL-6 receptor to prevent inflammation. Similarly, Interleukin-1 (IL-1) blockers like anakinra (Kineret) target the IL-1 inflammatory protein, though they are prescribed less frequently.
B-cell inhibitors represent another approach to treating RA. Drugs such as rituximab (Rituxan) target and deplete B-cells, a type of white blood cell that contributes to the inflammatory cascade and autoantibody production in RA. By reducing the number of these cells, rituximab helps to dampen the overall autoimmune response and can lead to improvements in disease activity.
T-cell inhibitors interfere with the activation of T-cells, another white blood cell involved in the immune response. Abatacept (Orencia) is a selective co-stimulation modulator that blocks the communication signals required to activate T-cells. This action interrupts the inflammatory process at an earlier stage compared to some other biologics, reducing the downstream effects that cause joint damage.
Methods of Administration
The delivery of biologic medications is a practical consideration for treatment. These drugs are administered either through subcutaneous injection or by intravenous (IV) infusion. Biologics cannot be taken orally because their large protein structures would be broken down by the digestive system.
Subcutaneous injections deliver medication into the fatty tissue just beneath the skin. This method is often designed for self-administration at home using a prefilled syringe or an auto-injector pen. The frequency of these injections varies by biologic, ranging from once or twice a week to every few weeks.
Intravenous infusions require the medication to be delivered directly into a vein in a clinical setting, such as a doctor’s office or infusion center. The procedure can take several hours to complete. While infusions are less frequent than injections, often occurring every few weeks to months, they require more time at a medical facility.
Understanding Potential Risks and Side Effects
A primary consideration with biologic therapies is their effect on the immune system, which leads to an increased risk of infections. Because these drugs suppress specific parts of the immune response, the body’s ability to fight off pathogens can be diminished. This can make individuals more susceptible to upper respiratory infections, pneumonia, and skin infections.
Before starting treatment, patients are screened for latent infections, particularly tuberculosis (TB) and hepatitis B. This ensures that dormant infections are not reactivated once the immune system is suppressed by the medication. Patients on biologics should watch for signs of infection and seek medical advice if they develop a fever or other unexplained symptoms.
Reactions at the site of administration are also possible. For subcutaneous injections, some people may experience redness, swelling, or pain at the injection site. With intravenous infusions, reactions can occur during or shortly after the procedure, causing symptoms like itchiness or changes in blood pressure. These reactions are often mild, but any such experiences should be communicated to a healthcare provider.
Factors in Treatment Selection
The decision to use a specific biologic is made between the patient and their rheumatologist, taking several factors into account.
- The severity and activity of the RA play a large part in the decision. More aggressive forms of the disease may warrant a different therapeutic approach than less active cases.
- A person’s overall health and any co-existing medical conditions are carefully considered. The presence of other health issues, such as pulmonary disease or a history of certain infections, can influence the choice of biologic.
- Patient preference and lifestyle are additional components. An individual’s comfort level with self-injecting versus traveling to a clinic for an infusion can impact the choice of medication.
- How a person has responded to conventional DMARDs or other biologics in the past can provide valuable information for guiding future treatment decisions. If one class of biologic was not effective, a different class may be chosen.
- Practical considerations such as insurance coverage and the cost of the medication are also factors. The financial aspect of treatment is an important part of the conversation to ensure the chosen therapy is sustainable.