Pharmacy News

FDA Approves Anthrax Antibody Product

Kate Traynor

BETHESDA, MD 21 Mar 2016—FDA on March 21 announced the approval of obiltoxaximab for i.v. injection for the treatment and prevention of inhalational anthrax in certain circumstances.

The labeling (PDF) for the monoclonal antibody therapy states that it is indicated, in conjunction with appropriate antimicrobial therapy, for the treatment of inhalational anthrax in adults and pediatric patients.

Obiltoxaximab, which will be sold as Anthim by Elusys Therapeutics Inc., is indicated for prophylaxis against inhalational anthrax only when no appropriate alternative therapy exists and the potential benefit from use of the monoclonal antibody outweighs the risk of serious hypersensitivity reactions.

FDA's approval of obiltoxaximab was based on efficacy studies in animal models and safety studies conducted with healthy human volunteers.

A boxed warning in the labeling for obiltoxaximab cautions that hypersensitivity reactions, including anaphylaxis, occurred in about 10% of the healthy volunteers. The labeling states that obiltoxaximab should be administered in monitored settings by healthcare providers who have been trained to manage anaphylaxis.

The most frequently reported adverse events in clinical studies included headache, pruritus, upper respiratory tract infection, cough, injection-site reactions, hives, and nasal congestion.

The labeling for obiltoxaximab describes it as a chimeric monoclonal antibody that targets a component of the Bacillus anthrasis toxin and has no direct antimicrobial activity.

The recommended dosage of obiltoxaximab in adults weighing at least 40 kg is a single 16-mg/kg dose infused intravenously over 90 minutes. A weight-based dosage, as described in a table in the labeling, is recommended for adults weighing less than 40 kg and for pediatric patients.

All patients should be premedicated with diphenhydramine before the obiltoxaximab infusion starts.

Detailed instructions for diluting obiltoxaximab in 0.9% Sodium Chloride Injection, USP, and preparing doses for administration, are included in the labeling.

Obiltoxaximab will be supplied in 600-mg single-dose vials that should be refrigerated at 2–8 °C in the original carton until use. The product was developed with federal biodefense funding and is intended for inclusion in the Strategic National Stockpile.


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