• Enbrel starts to have some effect within one to two weeks, although it may take 3 to 6 months for the full effects to develop.
• Effects of Enbrel include less pain, stiffness, and swelling, and improvements in movement and laboratory markers of inflammation.
• In some studies, over 42% of people achieved a definite clinical response (ACR 50) by month 3 and 15% achieved a significant clinical response (ACR 70) by month 3.
• Trials have also shown using Enbrel in combination with methotrexate increases response.

Enbrel (etanercept) is a subcutaneous (under the skin) injection that is administered either once or twice a week and is approved to treat several inflammatory conditions such as psoriasis and rheumatoid arthritis. It belongs to the class of medicines called TNF inhibitors.

Research has shown that Enbrel starts to have some effect within one to two weeks of starting treatment, and most people experienced some relief within 3 months. Further improvements were seen for up to six months.

Effects noticed include less pain, stiffness, and swelling. Improvements in movements and also in laboratory values such as ESR and CRP were also noted. In some studies, over 42% of people achieved a definite clinical response (ACR 50) by month 3. Trials have also shown using Enbrel in combination with methotrexate increases response.

Enbrel (etanercept) works by reducing the actions of TNF, which is a naturally occurring cytokine produced by the immune system. In some conditions, such as psoriasis or rheumatoid arthritis, the immune system produces too much TNF, which causes excessive inflammation and joint destruction.

Enbrel acts as a decoy TNF receptor, binding TNF and rendering it inactive. It belongs to the class of medicines called tumor necrosis factor (TNF) blockers. It may also be called a biological. Biologics only target specific parts of the immune system.

How effective is Enbrel?

Trials investigating the efficacy of Enbrel use a measure called the American College of Rheumatology (ACR) response. This is defined as follows:

• ACR 20: A 20% improvement in the number of tender and number of swollen joints, and a 20% improvement in three of the following five criteria: patient global assessment, physician global assessment, functional ability measure [most often Health Assessment Questionnaire (HAQ)], visual analog pain scale, and erythrocyte sedimentation rate or C-reactive protein (CRP)
• ACR 50: A 50% improvement in the number of tender and number of swollen joints, and a 50% improvement in three of the following five criteria: patient global assessment, physician global assessment, functional ability measure, visual analog pain scale, and CRP
• ACR 70: A 70% improvement in the number of tender and number of swollen joints, and a 70% improvement in three of the following five criteria: patient global assessment, physician global assessment, functional ability measure, visual analog pain scale, and CRP
• A hybrid ACR response measure (ACR N) may also be reported.

Research has shown the following:

• Enbrel 10mg or 25mg twice a week for 6 months: 62% achieved an ACR 20 by month 3; 41% had achieved an ACR 50 by month 3; 15% had achieved an ACR 70 by month 3
• Enbrel 25mg twice a week for 6 months in addition to methotrexate (MTX): 66% achieved an ACR 20 by month 3; 42% had achieved an ACR 50 by month 3; 15% had achieved an ACR 70 by month 3
• Enbrel 25mg twice a week compared to MTX (7.5mg/week to 20 mg/week): 62% Enbrel/ 56% MTX achieved an ACR 20 by month 3; 29% Enbrel/24% MTX had achieved an ACR 50 by month 3; 13% Enbrel/7% MTX had achieved an ACR 70 by month 3
• Enbrel 25mg twice weekly, MTX (7.5mg/week to 20 mg/week), Vs. Enbrel/MTX combined: Results at month 12 favored combination of Enbrel and MTX with ACR 20:75%, ACR 50:63%, ACR 70:40%, and ACR N: 63%.

What is Enbrel used for?

Enbrel is approved to treat the following conditions:

• Rheumatoid arthritis
• Plaque psoriasis in adults and children who are at least 4 years old
• Psoriatic arthritis
• Ankylosing spondylitis
• Polyarticular juvenile idiopathic arthritis in children who are at least 2 years old.

It is sometimes used in combination with methotrexate when used to treat rheumatoid arthritis and psoriatic arthritis.

How does Enbrel work?

Although the exact cause of many diseases, such as psoriasis or rheumatoid arthritis, is not known, experts do know that the immune system plays a role.

Normally our immune system protects us from infection and helps our tissues to repair. In some people, the immune system does not function as it should and produces abnormal levels of immune cells or factors. One of these factors is called TNF (tumor necrosis factor).

TNF is a naturally occurring cytokine (cytokines are small proteins that are involved in interactions and communications between cells). Cytokines and other proteins play an important role in the development of many inflammatory conditions such as psoriasis and rheumatoid arthritis, and the resulting joint destruction. Elevated levels of TNF are found in the tissues and body fluids of people with these conditions.

TNF binds to one of two receptors on cells – these are called p55 TNF receptor or p75 TNF receptor. Enbrel acts as a decoy p75 TNF receptor, which means both TNF-alpha and TNF-beta bind to it instead of the cell surface TNF receptors. This renders TNF inactive.

A fragment of human immunoglobulin G1 that is attached to the structure of Enbrel gives it a more profound and long-lasting effect than naturally occurring soluble TNF receptors.

How is Enbrel administered?

Enbrel is administered by subcutaneous injection (this means it is given just under the skin, using a very fine needle).

It is usually administered once or twice a week, depending on the condition being treated, for example:

• Adult rheumatoid arthritis, Ankylosing spondylitis, and Psoriatic arthritis: 50mg once weekly
• Psoriasis: 50mg twice weekly for three months then once weekly thereafter.

Enbrel can either be administered by a physician or nurse or people needing it can be taught how to self-administer.