VYVGART
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VYVGART (VYVGART).
Neonatal Fc receptor (FcRn) antagonist; reduces IgG recycling, lowering pathogenic IgG autoantibody levels.
| Metabolism | Metabolized by catabolic pathways into small peptides and amino acids. |
| Excretion | Efgartigimod alfa is catabolized by general protein degradation pathways; no renal or biliary excretion of intact drug. Less than 1% of the dose is excreted unchanged in urine. |
| Half-life | Terminal half-life is approximately 80-120 hours (mean ~4 days). This supports a dosing interval of every 2 weeks after the initial weekly loading phase. |
| Protein binding | Efgartigimod alfa is a human IgG1 antibody fragment; as a protein, it is not bound to plasma proteins in a conventional sense. It is present in plasma as free monoclonal antibody. |
| Volume of Distribution | Volume of distribution is approximately 0.3-0.4 L/kg, indicating distribution primarily within the vascular space and limited extravascular penetration. |
| Bioavailability | Administered intravenously; bioavailability is 100% by the IV route. No other routes are clinically relevant. |
| Onset of Action | Clinical improvement in myasthenia gravis symptoms may be observed within 1-2 weeks after the first infusion, as measured by MG-ADL score reduction. |
| Duration of Action | Duration of effect typically lasts 6-8 weeks per treatment cycle. Repeated cycles are given based on clinical response, with a minimum interval of 50 days between cycles. |
| Molecular Weight | 54600 |
10 mg/kg intravenously over 1 hour, once weekly for 4 weeks (4 doses total), then 10 mg/kg intravenously over 1 hour every 2 weeks starting at week 5.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (eGFR >= 30 mL/min/1.73 m²). Not studied in severe renal impairment (eGFR < 30 mL/min/1.73 m²) or end-stage renal disease; use not recommended. |
| Liver impairment | No dose adjustment required for mild hepatic impairment (Child-Pugh class A). Not studied in moderate or severe hepatic impairment (Child-Pugh class B or C); use not recommended. |
| Pediatric use | Not approved for pediatric patients (safety and efficacy not established for children < 18 years). |
| Geriatric use | No specific dose adjustment required for geriatric patients (>= 65 years) based on population pharmacokinetic analysis; monitor for adverse reactions due to potential age-related comorbidities and polypharmacy. |
| 1st trimester | No adequate human data; based on animal studies, potential for harm cannot be ruled out. IgG antibodies cross the placenta in increasing amounts as pregnancy progresses; however, the greatest risk of fetal harm is during organogenesis in the first trimester. Use only if maternal benefit justifies fetal risk. |
| 2nd trimester | IgG antibodies cross the placenta throughout pregnancy; however, the second trimester is associated with lower placental transfer compared to the third. No adequate human studies; use with caution. |
| 3rd trimester | IgG actively crosses the placenta, especially in the third trimester, leading to potential neonatal immunosuppression. Avoid use unless clearly needed. |
Clinical note
Comprehensive clinical and safety monograph for VYVGART (VYVGART).
| Placental transfer | Placental transfer occurs as with other IgG antibodies; transfer increases with gestational age, particularly in the third trimester. Based on molecular structure, expected to cross placenta. |
| Breastfeeding |
■ FDA Black Box Warning
No black box warning.
| Serious Effects |
Hypersensitivity to efgartigimod or any excipients
| Precautions | Increased risk of infections, Hypersensitivity reactions including anaphylaxis, Headache, Aseptic meningitis |
| Food/Dietary | No known food interactions. No dietary restrictions required. |
| Clinical Pearls | VYVGART (efgartigimod alfa-fcab) is a neonatal Fc receptor (FcRn) antagonist approved for generalized myasthenia gravis (gMG) in AChR antibody-positive patients. Monitor for infections due to IgG reduction; administer IV over 1 hour weekly for 4 weeks. Consider Pneumocystis jirovecii prophylaxis if used with immunosuppressants. Not for myasthenic crisis. |
Loading safety data…
| Efgartigimod is a human IgG1 antibody fragment; likely excreted into breast milk in low amounts. Theoretical risk of local gastrointestinal effects and hypersensitivity in the infant. Consider developmental benefit of breastfeeding versus maternal need for drug. Monitor infant for adverse effects. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | VYVGART (efgartigimod alfa) is an IgG1 antibody fragment. As a large protein, it is not expected to cross the placenta significantly in the first trimester, but placental transfer increases in the second and third trimesters. There are no adequate and well-controlled studies in pregnant women. In animal reproduction studies, no adverse developmental effects were observed in monkeys at exposures up to 16 times the human clinical exposure. However, due to FcRn inhibition, potential risks include fetal hypogammaglobulinemia and reduced passive immunity transfer. Caution is advised in the second and third trimesters. |
| Fetal Monitoring | Monitor maternal infections and immunoglobulins (IgG levels) due to FcRn inhibition. Monitor fetal growth and development with serial ultrasounds if used during pregnancy. Assess newborn for infections, hypogammaglobulinemia, and response to vaccinations. No specific monitoring for efgartigimod itself is required. |
| Fertility Effects | No human data on fertility. In animal studies (monkeys), efgartigimod alfa had no adverse effects on male or female fertility at exposures up to 16 times the human clinical exposure. However, due to its immunomodulatory mechanism, theoretical risk of affecting reproductive immune function cannot be excluded. No fertility impairment observed in preclinical studies. |
| Patient Advice | This medicine lowers antibody levels to improve muscle weakness. · You will receive IV infusions once weekly for 4 weeks per cycle. · Report any signs of infection (fever, sore throat, cough) immediately. · Avoid live vaccines during treatment. · Tell your doctor if you are pregnant or breastfeeding. |