Regulatory Decision Summary for Anthrasil
Review decision
The Regulatory Decision Summary explains Health Canada’s decision for the product seeking market authorization. The Regulatory Decision Summary includes the purpose of the submission and the reason for the decision.
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What was the purpose of this submission?
The intent of this Extraordinary Use New Drug Submission (EUNDS) was to seek marketing authorisation of Anthrasil for the treatment of adult and pediatric patients with toxemia associated with inhalational anthrax.
This submission was accepted as an extraordinary use new drug submission (EUNDS), under the Health Canada EUND pathway. Since it is not ethical or feasible to conduct placebo-controlled clinical trials in humans with inhalational anthrax, the effectiveness of Anthrasil is based on efficacy studies demonstrating a survival benefit in animal models of inhalational anthrax infection.
Why was the decision issued?
Inhalational anthrax is a serious condition associated with high mortality. Currently in Canada, no specific licensed therapies are available to treat inhalational anthrax. Symptomatic anthrax patients are treated with antimicrobial agents with known activity against B. anthracis. Although these therapies can address bacteremia caused by the organism, they do not directly inhibit toxemia, the main cause of anthrax pathogenesis.
Efficacy studies were conducted in two established animal models for inhalational anthrax (rabbit and rhesus macaque). Efficacy was established by increased survival compared to placebo in both animal species when Anthrax Immune Globulin Intravenous (AIGIV) was used as monotherapy. In addition, there was a trend of higher survival rates in animals who received both AIGIV and appropriate antibiotic therapy compared to animals who received antibiotic therapy plus non-specific Immune Globulin Intravenous (IGIV), although the difference in survival rates did not reach statistical significance. The addition of AIGIV to appropriate antibiotic therapy has the potential benefit to further lower the mortality of this serious, life-threatening disease.
Safety data were obtained in healthy volunteers and patients. There were no special safety concerns for AIGIV, and it is expected that adverse reactions that have been reported with other human hyperimmune and IGIV products may also occur with AIGIV (e.g.: hypersensitivity reactions/ anaphylaxis).
There are some limitations in the submission, partly due to the nature of the EUNDS. There were no human efficacy data, and no efficacy and safety data in special populations (e.g. children). Those limitations are covered in the Product Monograph. If feasible, the proposed post-marketing studies could confirm the safety and efficacy of the product in humans with inhalational anthrax, and the appropriateness of the recommended dosing regimen. In addition, data in special populations could be provided, if Anthrasil is used in these populations.
Overall, the potential benefit of AIGIV, as inferred from the submitted animal efficacy studies, exceeds the known and expected risks of the product.
For more information on Health Canadas decision, please view the Summary Basis of Decision.
Decision issued
Approved; issued Notice of Compliance in accordance with the Food and Drug Regulations.