The Food and Drug Administration (FDA) has approved the monoclonal antibody raxibacumab to treat inhalational anthrax (in combination with antibiotics) and to prevent inhalational anthrax when other alternative treatments aren't available or are inappropriate for the patient. Monoclonal antibodies are drugs that mimic endogenous antibodies by identifying and neutralizing foreign material. Raxibacumab is the first antianthrax drug to work in this manner.

Because anthrax is rare and exposure to it could be fatal, raxibacumab was evaluated for efficacy under the FDA's Animal Efficacy Rule, which allows animal studies to be used when it's not ethical or feasible to conduct human clinical trials. Three trials (one with monkeys, two with rabbits) compared raxibacumab with placebo in treating anthrax. Another trial, also with rabbits, compared a combination of antibiotics and raxibacumab with antibiotics alone. Additional trials with rabbits and monkeys examined the effectiveness of the drug when used as prophylaxis. All of the trials found raxibacumab to be therapeutically effective.

Raxibacumab is approved for use in pediatric and adult patients, although there have been no pediatric trials. Small human trials in adults were conducted to determine drug safety and found that infusion reactions are possible; premedication with diphenhydramine is recommended. The most common adverse effects were rash, pain in the extremities, pruritus, and somnolence.

Nurses should be aware of drugs that can be used to treat anthrax because anthrax outbreaks could occur as a result of bioterrorist attacks. If there is an event requiring IV administration of this drug, the label should be read carefully for full information regarding administration.

To read the FDA news release regarding the approval, go to http://1.usa.gov/XnoLSs.