RAXIBACUMAB
Clinical safety rating: caution
Comprehensive clinical and safety monograph for RAXIBACUMAB (RAXIBACUMAB).
Raxibacumab is a monoclonal antibody that binds to the protective antigen (PA) component of Bacillus anthracis toxins, preventing PA from binding to host cell receptors and thereby inhibiting the intracellular entry of lethal factor and edema factor. This neutralizes the lethal and edema toxins, reducing pathogenicity.
| Metabolism | Monoclonal antibodies are generally degraded into small peptides and amino acids via catabolic pathways, similar to endogenous immunoglobulins. Raxibacumab metabolism is not mediated by hepatic CYP450 enzymes. |
| Excretion | Primarily renal excretion as intact protein; >90% of administered dose recovered in urine over 48 hours. |
| Half-life | Terminal elimination half-life approximately 12-24 hours (mean ~18 hours) in patients with normal renal function; half-life extends in renal impairment. |
| Protein binding | Negligible protein binding (<1% bound) as a monoclonal antibody. |
| Volume of Distribution | Volume of distribution approximately 0.15 L/kg, indicating limited extravascular distribution consistent with a large protein. |
| Bioavailability | Intravenous: 100%; Subcutaneous: Approximately 60-70% (mean ~65%). |
| Onset of Action | Intravenous: Onset within 2 hours after infusion; subcutaneous: Onset within 4-6 hours. |
| Duration of Action | Duration of action corresponds to sustained plasma concentrations; detectable antirabies antibody levels persist for at least 21 days post-dose. |
Single intravenous dose of 40 mg/kg administered over 30 minutes.
| Dosage form | INJECTABLE |
| Renal impairment | No dosage adjustment required for any degree of renal impairment including end-stage renal disease. |
| Liver impairment | No dosage adjustment required for any degree of hepatic impairment. |
| Pediatric use | Safety and efficacy in pediatric patients have not been established. |
| Geriatric use | No specific dosage adjustment recommended; clinical studies included limited number of patients aged 65 and older. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for RAXIBACUMAB (RAXIBACUMAB).
| Breastfeeding | Unknown if excreted in human breast milk. M/P ratio not determined. Due to long half-life and potential for bleeding, caution advised; consider discontinuing breastfeeding during therapy. |
| Teratogenic Risk | FDA Pregnancy Category C. Animal studies show embryotoxicity at high doses; no adequate human studies. Avoid in pregnancy unless benefit outweighs risk. First trimester: potential for teratogenicity; second and third trimesters: risk of fetal hemorrhage due to antiplatelet effect. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Serious Effects |
None.
| Precautions | ["Hypersensitivity reactions, including anaphylaxis, have been reported. Monitor patients during infusion and have appropriate medical support available.","Infusion-related reactions (e.g., urticaria, pruritus, rash) may occur. Slow or stop infusion if severe.","Interference with immune response: As a monoclonal antibody, may interfere with the immune response to anthrax vaccination. Use with caution.","Limited clinical data: Efficacy is based on animal models; clinical efficacy in humans is not established."] |
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| Monitor maternal bleeding signs, platelet count, and coagulation parameters. Fetal ultrasound for growth and hemorrhage signs. Monitor for preterm labor or placental abruption. |
| Fertility Effects | No human data. Animal studies show no impairment of fertility at clinically relevant doses. Theoretical risk of anti-angiogenic effects on reproductive tissues. |