RENFLEXIS
Clinical safety rating: caution
Comprehensive clinical and safety monograph for RENFLEXIS (RENFLEXIS).
Renflexis (infliximab-abda) is a chimeric monoclonal antibody that binds with high affinity to tumor necrosis factor alpha (TNFα), neutralizing its pro-inflammatory activity. It inhibits TNFα binding to its receptors (TNFR1 and TNFR2), reducing inflammatory cell migration, cytokine production, and tissue damage.
| Metabolism | Infliximab is a monoclonal antibody not metabolized by hepatic enzymes; elimination occurs via intracellular catabolism following binding to target or via reticuloendothelial system; no cytochrome P450 involvement. |
| Excretion | Primarily eliminated via reticuloendothelial system degradation; renal excretion accounts for <1% of dose as unchanged drug; no significant biliary or fecal excretion. |
| Half-life | Terminal elimination half-life approximately 18-21 days (mean ~20 days) in patients with rheumatoid arthritis; supports every-8-week dosing interval. |
| Protein binding | Approximately 80-90% bound, primarily to IgG Fc receptors and weakly to albumin. |
| Volume of Distribution | Approximately 0.2-0.3 L/kg (4-6 L total), indicating limited extravascular distribution, consistent with a monoclonal antibody confined largely to plasma and interstitial fluid. |
| Bioavailability | Subcutaneous: 55-64% (mean ~60%) relative to IV administration. |
| Onset of Action | Subcutaneous: Clinical response may be observed within 2 weeks; IV: Improvement can be noted within 1-2 weeks. |
| Duration of Action | Subcutaneous or IV: Dosing every 8 weeks maintains therapeutic effect; duration correlates with serum trough levels >5 μg/mL. |
5 mg/kg intravenously over at least 2 hours at 0, 2, and 6 weeks, then every 8 weeks.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for renal impairment. Not studied in severe renal impairment. |
| Liver impairment | No dose adjustment recommended for mild or moderate hepatic impairment. Not studied in severe hepatic impairment (Child-Pugh C). |
| Pediatric use | For pediatric patients (6-17 years): 5 mg/kg intravenously over at least 2 hours at 0, 2, and 6 weeks, then every 8 weeks. |
| Geriatric use | No specific dose adjustment; use caution due to higher infection risk and comorbidities. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for RENFLEXIS (RENFLEXIS).
| Breastfeeding | Infliximab is excreted into human breast milk in low concentrations. The milk-to-plasma (M/P) ratio is approximately 0.005-0.02, indicating minimal transfer. Limited studies suggest that ingested amounts are unlikely to cause systemic effects in breastfed infants, given low oral bioavailability. Caution is advised due to potential immune suppression; benefits of breastfeeding should be weighed against risks. |
| Teratogenic Risk | Infliximab (RENFLEXIS) is an IgG1 monoclonal antibody that crosses the placenta, with fetal exposure increasing as pregnancy progresses, particularly after the second trimester. First trimester: Limited data suggest no significant increase in major malformations; however, data are insufficient to rule out risk. Second/Third trimester: Higher fetal concentrations may occur; associated with increased risk of infections (e.g., opportunistic infections) in neonates exposed in utero. Live vaccines should be avoided in infants for 6 months following in utero exposure. |
■ FDA Black Box Warning
WARNING: SERIOUS INFECTIONS and MALIGNANCY. Patients treated with infliximab products are at increased risk for serious infections (including tuberculosis, bacterial sepsis, invasive fungal infections such as histoplasmosis, and opportunistic infections) that may lead to hospitalization or death. Malignancies, including lymphoma, have been reported. A higher rate of lymphoma and other malignancies has been observed in pediatric patients compared to adults.
| Serious Effects |
["Moderate to severe heart failure (NYHA Class III/IV) (use in mild heart failure requires caution)","Severe active infections (including abscesses)","Hypersensitivity to infliximab or any murine proteins","Patients with demyelinating disorders (relative contraindication)"]
| Precautions | ["Serious infections (including TB, invasive fungal, and opportunistic infections); screen for latent TB before initiation","Hepatitis B virus reactivation","Hepatotoxicity (including acute liver failure, jaundice, and autoimmune hepatitis)","Malignancies (lymphoma and other cancers; especially in pediatric patients)","Congestive heart failure (worsening or new onset)","Hematologic reactions (pancytopenia, leukopenia, neutropenia, thrombocytopenia)","Hypersensitivity reactions (including anaphylaxis and serum sickness-like reactions)","Autoimmune disorders (lupus-like syndrome)","Neurologic events (demyelinating disease, new or worsening MS, seizures)","Use with biologic DMARDs risk of increased infection"] |
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| Fetal Monitoring | Monitor for signs of infection in both mother and fetus/neonate. During pregnancy, assess for opportunistic infections (e.g., tuberculosis). Fetal ultrasound may be considered to monitor growth and development if clinically indicated. Neonates exposed in utero should be monitored for infections and should not receive live vaccines (e.g., BCG, rotavirus) within 6 months of birth if the mother received infliximab after week 22 of gestation. |
| Fertility Effects | Available data do not indicate a direct negative impact on fertility in males or females. Infliximab is used in autoimmune conditions that may themselves affect fertility, such as inflammatory bowel disease or rheumatoid arthritis. By controlling disease activity, it may improve fertility outcomes. No specific human studies on fertility have been conducted; animal studies show no impairment of fertility. |