TOFIDENCE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TOFIDENCE (TOFIDENCE).
Tofidence is an interleukin-6 (IL-6) receptor inhibitor. It binds to both soluble and membrane-bound IL-6 receptors, inhibiting IL-6-mediated signaling and reducing inflammatory cytokine production.
| Metabolism | Tofidence is metabolized via proteolysis into small peptides and amino acids. Hepatic metabolism does not play a significant role; it is not a substrate for cytochrome P450 enzymes. |
| Excretion | Tocilizumab (the active ingredient of TOFIDENCE) is eliminated via both renal and biliary routes. Approximately 60% of the dose is excreted unchanged in the urine, with the remainder eliminated via the hepatobiliary system as metabolites or unchanged drug in feces. |
| Half-life | The terminal elimination half-life of tocilizumab is concentration-dependent, ranging from 4 to 10 days at concentrations above 10 mcg/mL and up to 20 days at lower concentrations. This long half-life supports every-4-week dosing in rheumatoid arthritis. |
| Protein binding | Tocilizumab is approximately 89% bound to plasma proteins, primarily to albumin and, to a lesser extent, to alpha-1-acid glycoprotein. |
| Volume of Distribution | The volume of distribution (Vd) is approximately 4.4 L (0.06 L/kg for a 70 kg patient), indicating limited extravascular distribution, consistent with a monoclonal antibody that remains predominantly in the vascular space. |
| Bioavailability | Subcutaneous bioavailability is approximately 80% relative to intravenous administration, with a peak concentration reached at about 3–5 days post-injection. |
| Onset of Action | Following intravenous infusion, clinical effect (e.g., reduction in CRP) is observed within 2 weeks. Subcutaneous injection has a slightly delayed onset, typically within 2–4 weeks. |
| Duration of Action | The pharmacodynamic effect (e.g., IL-6 receptor blockade) persists for 4–6 weeks after a single dose. Sustained clinical response is maintained with every-4-week (IV) or every-2-week (SC) dosing regimens. |
10 mg/kg intravenously every 4 weeks after a loading dose of 10 mg/kg at week 0 and week 2, for adult patients weighing at least 40 kg with moderate to severe active rheumatoid arthritis.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (CrCl ≥30 mL/min). Not studied in severe renal impairment (CrCl <30 mL/min) or end-stage renal disease; use with caution. |
| Liver impairment | No dose adjustment required for mild hepatic impairment (Child-Pugh A). Not studied in moderate to severe hepatic impairment (Child-Pugh B or C); use is not recommended. |
| Pediatric use | For juvenile idiopathic arthritis (JIA) in patients aged 2 years and older: 10 mg/kg intravenously every 4 weeks after a loading dose of 10 mg/kg at week 0 and week 2; maximum dose 800 mg per infusion. No data for patients weighing less than 10 kg. |
| Geriatric use | No specific dose adjustment required for elderly patients (≥65 years). Greater frequency of infections and decreased renal function should be considered; monitor closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TOFIDENCE (TOFIDENCE).
| Breastfeeding | It is unknown if tocilizumab is excreted in human milk. Maternal IgG is present in colostrum and breast milk, and tocilizumab is a monoclonal antibody (IgG1). Given the large molecular weight, excretion is likely minimal. M/P ratio not available. Caution is advised; consider risk of infant immunosuppression. |
| Teratogenic Risk | Tocilizumab (TOFIDENCE) is an IL-6 receptor antagonist. Data from animal studies and limited human reports indicate an increased risk of miscarriage and preterm birth. In the first trimester, no clear pattern of major congenital malformations has been established, but caution is warranted due to IL-6's role in placental development. Second and third trimester exposure may increase risk of preterm labor and low birth weight. Avoid use unless benefit outweighs risk. |
■ FDA Black Box Warning
Risk of serious infections leading to hospitalization or death, including tuberculosis, invasive fungal infections, and other opportunistic pathogens. Patients should be screened for tuberculosis prior to therapy.
| Serious Effects |
["Known hypersensitivity to tocilizumab or any component of the formulation","Active, severe infections (including sepsis, tuberculosis, or opportunistic infections)"]
| Precautions | ["Serious infections: Caution in patients with chronic or recurrent infections.","Gastrointestinal perforation: Monitor for new-onset abdominal symptoms.","Hepatotoxicity: Monitor liver enzymes; dose adjustment may be required.","Neutropenia and thrombocytopenia: Monitor blood counts periodically.","Hypersensitivity reactions: Including anaphylaxis, discontinue if occurs.","Demyelinating disorders: May worsen existing disorders or precipitate new onset.","Vaccinations: Avoid live vaccines during therapy."] |
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| Fetal Monitoring | Monitor for signs of infection in mother and fetus/neonate. Obtain baseline liver function tests and complete blood count. Monitor for maternal preterm labor, fetal growth restriction via ultrasound, and neonatal infections after delivery. |
| Fertility Effects | Tocilizumab may reduce fertility in females of childbearing potential by inhibiting IL-6, which is involved in ovarian follicular development and ovulation. Effects are likely reversible upon discontinuation. No specific data on male fertility. |