Raxibacumab is a recombinant, fully human IgG1λ monoclonal antibody directed against the protective antigen (PA) component of Bacillus anthracis toxin. It is classified as an anthrax protective antigen-directed antibody and is used for the treatment of inhalational anthrax in combination with appropriate antibacterial therapy, as well as for post-exposure prophylaxis when alternative therapies are unavailable or inappropriate.
Raxibacumab has an approximate molecular weight of 145.9–146 kDa and consists of two identical heavy chains and two identical lambda light chains. FDA documentation identifies its CAS Registry Number as 565451-13-0.
| Parameter | Details |
|---|---|
| Product Name | Raxibacumab |
| CAS Number | 565451-13-0 |
| UNII | 794PGL549S |
| Molecular Type | Recombinant monoclonal antibody |
| Antibody Class | Human IgG1λ |
| Approx. Molecular Weight | 145.9–146 kDa |
| Therapeutic Class | Anthrax protective antigen-directed antibody |
| ATC Code | J06BC02 |
| Route | Intravenous |
| Dosage Form | Injection |
| Target | Protective antigen (PA) of Bacillus anthracis |
FDA's Purple Book identifies raxibacumab as an intravenous injection supplied as a 1,700 mg/34 mL (50 mg/mL) single-dose vial.
Raxibacumab is a biological drug substance rather than a conventional small-molecule API. Therefore, conventional molecular-formula, melting-point, logP and small-molecule impurity specifications are not appropriate primary quality attributes.
The molecule is a fully human IgG1λ monoclonal antibody with a molecular weight of approximately 145.9 kDa. FDA characterization describes it as consisting of two identical heavy chains and two identical light chains.
CAS: 565451-13-0
Molecular weight: approximately 145.9 kDa
Isoelectric point: approximately 9, as reported in PubChem.
Raxibacumab is used as an anthrax-directed monoclonal antibody for:
Its clinical use is associated with anthrax caused by Bacillus anthracis.
Raxibacumab specifically binds to the protective antigen (PA) component of B. anthracis toxin. PA normally participates in the delivery of the enzymatic toxin components lethal factor (LF) and edema factor (EF) into host cells.
By binding PA, raxibacumab inhibits PA interaction with cellular receptors and thereby prevents toxin-mediated cellular entry. It therefore acts against the toxin pathway rather than functioning as a conventional antibacterial agent. FDA describes its mechanism as binding the protective antigen of B. anthracis.
Because raxibacumab is a recombinant monoclonal antibody, quality control should focus on biologic-specific critical quality attributes rather than conventional small-molecule API tests.
Typical analytical characterization can include:
FDA's original quality assessment concluded that the manufacturing process produced a product that was pure and potent, with controls for infectious-agent risks and validated manufacturing conditions.
Raxibacumab is manufactured as a recombinant human IgG1λ monoclonal antibody using recombinant DNA technology in a mammalian cell expression system. PubChem identifies a murine cell expression system for production.
Manufacturing and release of this type of biological API require controlled upstream and downstream processing, purification, viral-safety controls, formulation, aseptic processing and extensive characterization.
The current labeled product contains 50 mg/mL raxibacumab, with a formulation pH of 6.5.
The marketed formulation is supplied as a 1,700 mg/34 mL (50 mg/mL) sterile, preservative-free solution in a single-use vial. The solution is described as clear to opalescent and colorless to pale yellow.
Storage conditions:
After preparation, the labeled infusion solution is stable for 8 hours at room temperature under the specified preparation conditions.
Depending on the intended application, documentation for Raxibacumab API/manufacturing programs may include:
Raxibacumab requires specialized biologics manufacturing capabilities and comprehensive characterization because it is a recombinant monoclonal antibody rather than a conventional synthetic API.
A qualified manufacturing program should emphasize:
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.1% |
| Heavy Metals | NMT 20 ppm |
| pH (1% Solution) | 6.5 |
| Individual Impurity | NMT 0.10% |
| Total Impurities | NMT 0.50% |
| Water Content | NMT 1.0% |