GENERIC NAME: abatacept

BRAND NAME: Orencia

DRUG CLASS AND MECHANISM: Abatacept is an injectable, synthetic (man-made) protein produced by recombinant DNA technology that is used for treating rheumatoid arthritis. 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 slows the damage to bones and cartilage and relieves the symptoms and signs of arthritis. Abatacept was approved by the FDA in December, 2005.

PRESCRIPTION: Yes GENERIC AVAILABLE: No

PREPARATIONS: Powder for Injection: 250 mg STORAGE: Refrigerate between 2-8�C (36-46�F).

PRESCRIBED FOR: Abatacept is used alone or in combination with other drugs for the treatment of adult patients with moderate to severe rheumatoid arthritis who have not adequately responded to one or more different disease-modifying drugs (i.e., drugs that slow the destruction of joints). Abatacept reduces the signs and symptoms of arthritis, slows the progression of damage to the joints, and improves the physical function of patients. Abatacept should not be combined with the disease-modifying TNF antagonists (e.g., Enbrel, Humira and Remicade).

DOSING: Abatacept is infused over 30 minutes. The initial dose of abatacept is followed by additional�doses two�and four weeks�after the first infusion�with further doses every 4 weeks thereafter. 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.

DRUG INTERACTIONS: Combining abatacept with TNF antagonists (e.g., Enbrel, Humira and Remicade) increases the occurrence of infections and provides no additional relief of symptoms. PREGNANCY: Abatacept has not been adequately evaluated in pregnant women.

NURSING MOTHERS: Abatacept has not been adequately evaluated in women who are nursing.

SIDE EFFECTS: The most common side effects include 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. Patients may also experience infusion related reactions such as dizziness, headache, hypotension or hypertension, nausea, wheezing, rash, nausea and shortness of breath. The most serious side effects are infections and cancer. Reference: FDA Prescribing Information