ACTEMRA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ACTEMRA (ACTEMRA).
ACTEMRA (tocilizumab) is a recombinant humanized monoclonal antibody that binds to both soluble and membrane-bound IL-6 receptors, inhibiting IL-6-mediated signaling. This blocks the pro-inflammatory effects of IL-6, including T-cell activation, B-cell differentiation, acute phase protein synthesis, and macrophage activation.
| Metabolism | Tocilizumab is primarily eliminated via two pathways: linear proteolytic catabolism (non-saturable) and target-mediated clearance (saturable, via IL-6 receptor binding). No specific metabolic enzymes are involved; it is not metabolized by CYP450 enzymes. |
| Excretion | Primarily via the reticuloendothelial system and target-mediated clearance; renal excretion is negligible (<10% as unchanged drug in urine). Biliary/fecal excretion is not a major route; however, after intravenous administration, approximately 80% of the dose is recovered in feces as metabolites over 4 weeks, with <1% as parent drug. The remainder is catabolized to amino acids. |
| Half-life | Terminal elimination half-life is approximately 13 days (range 11–17 days) for intravenous dosing and 8–10 days for subcutaneous dosing, due to concentration-dependent clearance and target-mediated elimination. Clinical context: The long half-life supports every-4-week dosing in stable patients. |
| Protein binding | Approximately 89% bound to plasma proteins, primarily to albumin; binding is reversible and non-saturable at therapeutic concentrations. |
| Volume of Distribution | Central volume of distribution (Vc) is approximately 6.4 L (0.09 L/kg for a 70 kg adult), and steady-state volume (Vss) is 7.5 L (0.11 L/kg). The small Vd indicates limited extravascular distribution, consistent with a large monoclonal antibody that remains largely in the vascular space. |
| Bioavailability | Subcutaneous: 80% absolute bioavailability (range 76–90%) after a single 162 mg dose. Intramuscular: Not approved or studied. No oral formulation. |
| Onset of Action | Intravenous: Clinical improvement (reduction in RA signs and symptoms) may be observed as early as 2 weeks, with maximal effect by 4–8 weeks. Subcutaneous: Similar onset, though slightly delayed due to absorption phase; measurable clinical response by 4–6 weeks. |
| Duration of Action | Duration of clinical effect per dose is approximately 4 weeks for IV every-4-week regimens and 1–2 weeks for subcutaneous weekly dosing, with sustained suppression of inflammatory markers (CRP, IL-6) for the dosing interval. Tachyphylaxis is not reported. |
| Action Class | Disease Modifying Anti-Rheumatoid Drugs (DMARDs)- Biologics |
4 mg/kg IV every 4 weeks initially, then increase to 8 mg/kg IV every 4 weeks based on clinical response (max 800 mg per dose). Alternatively, 162 mg SC every week or every other week for moderate to severe RA. For giant cell arteritis: 162 mg SC every week plus tapering corticosteroids.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment (CrCl <30 mL/min) or ESRD; use with caution. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Use with caution; 4 mg/kg IV or 162 mg SC every other week recommended. Child-Pugh C: Not recommended. |
| Pediatric use | For systemic juvenile idiopathic arthritis (sJIA) or polyarticular JIA: Weight ≥30 kg: 8 mg/kg IV every 2 weeks; Weight <30 kg: 12 mg/kg IV every 2 weeks. Max 800 mg per dose. |
| Geriatric use | No specific dose adjustment; no overall differences in safety or efficacy observed. However, higher incidence of infections in elderly may require monitoring. Use the lowest effective dose based on clinical response. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ACTEMRA (ACTEMRA).
| Breastfeeding | No human data; M/P ratio unknown; tocilizumab may be present in milk; caution advised; consider risk-benefit. |
| Teratogenic Risk | Animal studies show fetal harm; first trimester: avoid unless benefit outweighs risk; second/third trimester: only if clearly needed; potential for increased risk of infection in neonate. |
| Fetal Monitoring | Monitor for infections in mother and fetus; complete blood counts, liver function tests; fetal ultrasound if maternal infection suspected. |
■ FDA Black Box Warning
Risk of serious infections, including tuberculosis, invasive fungal infections (e.g., candidiasis, aspergillosis, pneumocystis), and other opportunistic pathogens. Patients should be screened for latent TB prior to therapy. Do not initiate ACTEMRA in patients with active infections.
| Serious Effects |
["Severe active infections (including localized infections)","Hypersensitivity to tocilizumab or any excipients"]
| Precautions | ["Serious infections (bacterial, fungal, viral) - monitor closely and interrupt therapy if infection develops","Hepatotoxicity - monitor liver enzymes; dose reduction or discontinuation may be needed for ALT/AST elevations","Neutropenia and thrombocytopenia - monitor neutrophil and platelet counts","Gastrointestinal perforation - caution in patients with history of diverticulitis or GI ulcers","Demyelinating disorders - consider risk/benefit in patients with multiple sclerosis or other demyelinating diseases","Hypersensitivity reactions (including anaphylaxis) - discontinue if serious reaction occurs","Vaccinations - avoid live vaccines during therapy"] |
| Food/Dietary |
Loading safety data…
| Fertility Effects | No human data; animal studies show no impairment; theoretical risk due to IL-6 inhibition affecting ovulation. |
| No significant food interactions. May be taken with or without food. |
| Clinical Pearls | Monitor for neutropenia, thrombocytopenia, and elevated liver enzymes. Do not initiate if ANC < 2000 cells/μL. Can cause GI perforation, especially in patients with diverticulitis. May increase risk of infections; screen for latent TB prior to initiation. Reduce dose in hepatic impairment. Not recommended with other biologic DMARDs or JAK inhibitors. |
| Patient Advice | Do not take if you have an active infection. · Report symptoms of infection, bleeding, or abdominal pain immediately. · Notify your doctor before any vaccination; avoid live vaccines. · You may need regular blood tests to monitor blood counts and liver function. |