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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VYVGART (VYVGART).
| Breastfeeding | It is unknown if efgartigimod alfa is excreted in human milk. However, as a protein (IgG1 fragment), it is likely present in low amounts. The M/P ratio is not determined. Efgartigimod alfa has a molecular weight of ~51 kDa and may undergo gastrointestinal digestion in the infant. Given its mechanism (FcRn inhibition), potential for accumulation is low. Consider benefits of breastfeeding, mother's need for VYVGART, and potential risk to the infant. No specific lactation data available. |
| 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. |
■ FDA Black Box Warning
No black box warning.
| Serious Effects |
History of severe hypersensitivity to efgartigimod alfa or any excipient.
| Precautions | ["Increased risk of infections","Hypersensitivity reactions including anaphylaxis","Headache","Aseptic meningitis"] |
Loading safety data…
| 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. |