abatacept (Orencia)

Abatacept is an injectable, synthetic (man-made) protein produced by recombinant DNA technology that is used for treating rheumatoid arthritis.

It is an immunesuppressant, a drug that suppresses the immune system that is similar to alefacept (Amevive) and belatacept (Nulojix). The immune system is responsible for protecting the body against foreign invaders, for example, infectious agents such as bacteria. In patients with rheumatoid arthritis, however, the immune system attacks and destroys normal tissue in and around the joints, causing pain, inflammation and damage to bone and cartilage. T-lymphocytes are important cells of the immune system.

Patients with rheumatoid arthritis have increased numbers of T-lymphocytes within the joints that are inflamed. The T-lymphocytes are "activated," that is, they multiply and release chemicals that promote the destruction of tissues surrounding the joints and cause the signs and symptoms of rheumatoid arthritis. Abatacept acts like an antibody and attaches to a protein on the surface of T-lymphocytes. By attaching to the protein, abatacept prevents the activation of the T-lymphocytes and blocks both the production of new T-lymphocytes and the production of the chemicals that destroy tissue and cause the symptoms and signs of arthritis. Abatacept relieves the symptoms and signs of arthritis and is a disease-modifying antirheumatic drug (DMARD) because it slows the damage to bones and cartilage and improves physical function.

Abatacept was approved by the FDA in December 2005.

What brand names are available for abatacept?

Orencia

Is abatacept available as a generic drug?

No

Do I need a prescription for abatacept?

Yes

The most common side effects of abatacept are:

• headache,
• upper respiratory tract infections and
• nausea.

Because abatacept depresses the immune system it reduces the body's ability to fight infection. Therefore, existing infections may worsen or new ones may develop.

Other important side effects include infusion-related reactions such as:

• dizziness,
• headache,
• hypotension,
• hypertension,
• nausea,
• wheezing,
• rash, and
• shortness of breath.

The most serious side effects are infections and cancer.

For adult patients, abatacept is infused over 30 minutes or injected under the skin. Patients weighing < 60 kg should receive a 500 mg dose, weighing 60-100 kg a 750 mg dose and weighing >100 kg a 1000 mg dose. The initial dose of abatacept is followed by additional doses two and four weeks after the first infusion with further doses every four weeks thereafter. Alternatively, adults may receive 125 mg by subcutaneous injection one day after the initial weight-based dose and then 125 mg by subcutaneous injection once weekly.

Patients 6 to 17 years old weighing less than 75 kg should receive a 10 mg/kg infusion initially. Pediatric patients weighing more than 75 kg should receive the adult infusion doses. The initial dose of abatacept is followed by additional doses two and four weeks after the first infusion with further doses every four weeks thereafter.

Combining abatacept with TNF antagonists (for example, Enbrel, Humira and Remicade) increases the occurrence of infections and provides no additional relief of symptoms. Abatacept may reduce the effect of live vaccines. Live vaccines should not be given at the same time as abatacept or within three months of discontinuation of abatacept. Pediatric patients should receive all recommended immunizations prior to starting abatacept.

Abatacept has not been adequately evaluated in pregnant women.

Abatacept has not been adequately evaluated in women who are breastfeeding.

What preparations of abatacept are available?

Powder for Injection: 250 mg. Prefilled Syringe: 125 mg/ml.

How should I keep abatacept stored?

Abatacept should be refrigerated between 2 C - 8 C (36 F - 46 F).