Mechanism of Action:

• Orencia, or abatacept, is a selective T-cell co-stimulation modulator used primarily for the treatment of rheumatoid arthritis (RA). It inhibits T-cell activation by binding to CD80 and CD86 on antigen-presenting cells, blocking interaction with CD28 on T-cells.

Indications:

• FDA-approved for moderate to severe rheumatoid arthritis in adults, and can be used as both monotherapy or in combination with other disease-modifying antirheumatic drugs (DMARDs).

• Also approved for use in juvenile idiopathic arthritis and psoriatic arthritis.

Administration Considerations:

• Available as an intravenous infusion or subcutaneous injection. The choice of administration depends on patient preference, tolerance, and accessibility.

• For intravenous use: the dosing schedule typically involves an initial dose, followed by additional doses at 2 and 4 weeks, and then every 4 weeks thereafter.

Important Drug Interactions:

• Concurrent use with biologic DMARDs, like TNF blockers, is not recommended due to an increased risk of infections.

• Live vaccines should be avoided during treatment with Orencia due to the potential for increased risk of infection.

Monitoring:

• Regular monitoring for infections is essential, as Orencia can compromise the immune system’s ability to fight infections.

• Before initiating therapy, screen for tuberculosis and other significant infections.

Adverse Effects:

• Common side effects include headache, upper respiratory infections, and nausea. Severe adverse effects can include serious infections and malignancies.

• Immediate hypersensitivity reactions may occur post-infusion; preparedness for emergency management is necessary during administration.

Use in Special Populations:

• Caution is advised in patients with chronic obstructive pulmonary disease (COPD) as worsening of the disease symptoms has been observed.

• Limited data are available on the use in pregnant women; it should only be used when the benefits outweigh the risks.

Pharmacokinetic Properties:

• Orencia has a dosage adjustment recommendation based on weight, which is particularly important in varying patient sizes to optimize therapeutic effects and minimize toxicity.

Patient Counseling Points:

• Educate patients on recognizing symptoms of infection and instruct them to report these immediately.

• Discuss the importance of adhering to the treatment schedule especially given the medication’s impact on the immune system.

Handling and Storage:

• Both the IV and subcutaneous forms should be stored in the refrigerator. Protect from light and do not shake. Subcutaneous injection devices should be allowed to reach room temperature before use for patient comfort.