Drug Guide
Efgartigimod alfa
Classification
Therapeutic: Immunoglobulin G (IgG) fragment reduction agent
Pharmacological: FcRn antagonist
FDA Approved Indications
- Myasthenia Gravis (MG) in adults with anti-AChR or anti-MuSK antibodies
Mechanism of Action
Efgartigimod alfa is a fragment antigen-binding (Fab) antibody that antagonizes the neonatal Fc receptor (FcRn), leading to increased degradation of IgG antibodies and decreased IgG levels, thereby reducing autoimmune activity.
Dosage and Administration
Adult: 10 mg/kg IV weekly for 4 weeks, then 10 mg/kg every 4 weeks, adjusted based on response and tolerability.
Pediatric: Not approved or established for pediatric use.
Geriatric: No specific dose adjustment; start cautiously, considering age-related decline in renal function.
Renal Impairment: No dose adjustment required; monitor closely.
Hepatic Impairment: No specific data; use with caution, monitor for adverse effects.
Pharmacokinetics
Absorption: Administered intravenously, so pharmacokinetics are not related to absorption from GI tract.
Distribution: Widely distributed with a large volume of distribution.
Metabolism: Metabolized via normal protein catabolic pathways; not metabolized by cytochrome P450 enzymes.
Excretion: Eliminated primarily through catabolism of the antibody fragment; specific excretion pathways are not well defined.
Half Life: Approximately 1 to 2 weeks.
Contraindications
- Hypersensitivity to efgartigimod alfa or any component of the formulation.
Precautions
- Monitor for infusion reactions, infections, and hypersensitivity. Use with caution in patients with active infections or immune deficiencies. Consider the risk of immunosuppression.
Adverse Reactions - Common
- Infusion-related reactions (Common)
- Respiratory infections (Common)
- Headache (Common)
Adverse Reactions - Serious
- Serious infections (Rare)
- Hypersensitivity or allergic reactions including anaphylaxis (Rare)
- Thromboembolic events (Rare)
Drug-Drug Interactions
- No known significant interactions
Drug-Food Interactions
- No known significant interactions
Drug-Herb Interactions
- No data available
Nursing Implications
Assessment: Monitor patient for signs of infusion reactions, infections, and changes in neuromuscular status.
Diagnoses:
- Risk for infections due to immunosuppression.
Implementation: Administer IV infusion as ordered, monitor vital signs during infusion, observe for adverse reactions.
Evaluation: Assess for improvement in myasthenic symptoms, monitor for adverse effects, adjust treatment as necessary.
Patient/Family Teaching
- Report any signs of allergic reaction or infusion reaction.
- Be aware of potential increased risk of infections.
- Follow schedule for infusions and appointments.
- Discuss any new or unusual symptoms promptly.
Special Considerations
Black Box Warnings:
- None at this time.
Genetic Factors: No specific genetic factors identified affecting therapy.
Lab Test Interference: May temporarily lower IgG levels; consider this when interpreting immunoglobulin labs.
Overdose Management
Signs/Symptoms: Potential allergic or infusion-related reactions, increased risk of infections.
Treatment: Discontinuation of therapy, supportive care, and emergency treatment for hypersensitivity reactions as necessary.
Storage and Handling
Storage: Store vials refrigerated at 2°C to 8°C (36°F to 46°F). Protect from light.
Stability: Stable up to the expiration date when stored properly.