Biologics for rheumatoid arthritis treatment

There have been some promising advances in the past few years in treating rheumatoid arthritis and other forms of inflammatory arthritis such as ankylosing spondylitis and psoriatic arthritis -- especially for those people who do not respond to disease-modifying drugs. The most important advance has been the development of a group of drugs called biologic response modifiers or biologics.

There are several biologics approved to treat arthritis. They include:

• Enbrel
• Humira
• Kineret
• Remicade
• Rituxan
• Orencia

There are also other biologics being studied to treat various forms of arthritis.

Biologics are genetically engineered drugs derived from human genes. They are designed to either inhibit or supplement a specific component of the immune system called cytokines.These cytokines play a pivotal role in either fueling or suppressing inflammation (a key component in several forms of arthritis such as rheumatoid arthritis and psoriatic arthritis).

Enbrel, Humira, and Remicade inhibit a cytokine called tumor necrosis factor or TNF. Kineret blocks the cytokine interleukin-1 (or IL-1). Rituxan selectively targets immune cells known as CD20-positive B cells.

What makes these drugs so different from other drugs used to treat RA that modify the immune system (see the DMARDs article) is that biologics affect a specific component of the immune system, not the entire immune system. Thus, these drugs theoretically have fewer side effects.

These drugs may take a few weeks to notice a significant effect.

As with any drugs that suppress the immune system, biologic therapy might pose some risks, since it could make your body more vulnerable to other infections and diseases. Patients should seek immediate medical attention if they develop persistent fever.

Biologics may also cause some chronic diseases in remission -- such as tuberculosis -- to flare up, and they are often not recommended for people with multiple sclerosis and other conditions such as congestive heart failure.

Since biologic therapy is only in its early stages of use, some of the long-term effects of using these medications simply aren't known, and your doctor will probably want to regularly monitor your health while using them. Biologics are also currently more expensive than conventional treatments. However, the evidence so far is that they work well and pose fewer risks than other systemic therapies.

One disadvantage to biologic medication is that it has to be given either by injection or by intravenous infusion; the latter approach can take two hours per session. However, the advantages of these drugs appear to be numerous.

Although animal studies have shown no effect on fertility or impairment of the fetus, these studies cannot always predict the effects in humans. Accordingly, pregnant women should receive these drugs only if clearly needed.

Researchers say that future agents, still in the early development stages, may be less expensive and will be taken orally. Also on the horizon are biologics that target different cytokines.

Here are some details on each drug:

Enbrel reduces joint inflammation by blocking a cytokine called tumor necrosis factor, or TNF.

Enbrel is given by self-injection under the skin once or twice a week. Many people learn to give their own injections or receive them from a family member who has received proper instruction. A kit is available from the manufacturer that makes drawing up the medicine and injecting it easier.

Studies on Enbrel suggest that it may cause irritation at the injection site.

Enbrel's effect can also weaken the immune system. Although rare, some people have developed serious infections while taking Enbrel. Anyone with a serious infection should stop taking Enbrel and resume it after being advised by a doctor. If you develop an infection, let your doctor know immediately as you need to be monitored closely.

Pregnant women should not take Enbrel because the effects on a developing child are unknown.