Raxibacumab Side Effects Center

Last updated on RxList: 12/2/2020
Raxibacumab Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Raxibacumab?

Raxibacumab Injection is indicated for the treatment of adult and pediatric patients with inhalational anthrax due to Bacillus anthracis in combination with appropriate antibacterial drugs, and for prophylaxis of inhalational anthrax when alternative therapies are not available or are not appropriate.

What Are Side Effects of Raxibacumab?

Common side effects of Raxibacumab Injection include rash, pain in extremities, itching, hives, and sleepiness.

Dosage for Raxibacumab

The dose of Raxibacumab Injection is based on the patient's body weight. Patients are premedicated with diphenhydramine.

What Drugs, Substances, or Supplements Interact with Raxibacumab?

Raxibacumab Injection may interact with other drugs. Tell your doctor all medications and supplements you use.

Raxibacumab During Pregnancy and Breastfeeding

Tell your doctor if you are pregnant before receiving Raxibacumab Injection. It is unknown if Raxibacumab Injection passes into breast milk or if it would affect a nursing infant. Consult your doctor before breastfeeding.

Additional Information

Our Raxibacumab Injection Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety of raxibacumab has been studied only in healthy volunteers. It has not been studied in patients with inhalational anthrax.

The safety of raxibacumab has been evaluated in 326 healthy subjects treated with a dose of 40 mg/kg in 3 clinical trials: a drug interaction trial with ciprofloxacin (Study 1), a repeat-dose trial of 20 subjects with the second raxibacumab dose administered ≥4 months after the first dose (Study 2), and a placebo-controlled trial evaluating single doses with a subset of subjects receiving 2 raxibacumab doses 14 days apart (Study 3). Raxibacumab was administered to 86 healthy subjects in Study 1. In Study 3, 240 healthy subjects received raxibacumab (217 received 1 dose and 23 received 2 doses) and 80 subjects received placebo.

The overall safety of raxibacumab was evaluated as an integrated summary of these 3 clinical trials. Of 326 raxibacumab subjects, 283 received single doses, 23 received 2 doses 14 days apart, and 20 received 2 doses more than 4 months apart. The subjects were aged 18 to 88 years, 53% female, 74% white, 17% black/African-American, 6% Asian, and 15% Hispanic.

Adverse Reactions Leading To Discontinuation Of Raxibacumab Infusion

Four subjects (1.2%) had their infusion of raxibacumab discontinued for adverse reactions: 2 subjects (neither of whom received diphenhydramine premedication) due to urticaria (mild), and 1 subject each discontinued for clonus (mild) and dyspnea (moderate).

Most Frequently Reported Adverse Reactions

The most frequently reported adverse reactions were rash, pain in extremity, pruritus, and somnolence.

Table 3: Adverse Reactions Reported in ≥1.5% of Healthy Adult Subjects Exposed to Raxibacumab 40 mg/kg Intravenously

Preferred TermPlacebo
n = 80 (%)
Single-Dose Raxibacumab
n = 283 (%)
Double-Dose Raxibacumab ≥4 Months Apart
n = 20(%)
Double-Dose Raxibacumab
2 Weeks Apart
n = 23 (%)
Total Raxibacumab Subjects
N = 326 (%)
Rash/Rash erythematous/Rash papular1 (13)9 (3.2)009 (2.8)
Pain in extremity1 (13)7(2.5)007(2.1)
Somnolence04(1.4)01 (4.3)5 (1.5)


For all subjects exposed to raxibacumab in clinical trials, the rate of rash was 2.8% (9/326) compared with 1.3% (1/80) of placebo subjects. Mild to moderate infusionrelated rashes were reported in 22.2% (6/27) of subjects who did not receive diphenhydramine premedication compared with 3.3% (2/61) of subjects who were premedicated with diphenhydramine in the ciprofloxacin/raxibacumab combination trial (Study 1). In the placebo-controlled raxibacumab study where all subjects received diphenhydramine (Study 3), the rate of rash was 2.5% in both placebo- and raxibacumab-treated subjects.

Less Common Adverse Reactions

Clinically significant adverse reactions that were reported in <1.5% of subjects exposed to raxibacumab and at rates higher than in placebo subjects are listed below:

  • Blood and Lymphatic System: Anemia, leukopenia, lymphadenopathy.
  • Cardiac Disorders: Palpitations.
  • Ear and Labyrinth: Vertigo.
  • General Disorders and Administration Site: Fatigue, infusion site pain, peripheral edema.
  • Investigations: Blood amylase increased, blood creatine phosphokinase increased, prothrombin time prolonged.
  • Musculoskeletal and Connective Tissue: Back pain, muscle spasms.
  • Nervous System: Syncope vasovagal.
  • Psychiatric: Insomnia.
  • Vascular: Flushing, hypertension.

The development of anti-raxibacumab antibodies was evaluated in all subjects receiving single and double doses of raxibacumab in Studies 1, 2, and 3. Immunogenic responses against raxibacumab were not detected in any raxibacumab-treated human subjects following single or repeat doses of raxibacumab.

The incidence of antibody formation is highly dependent on the sensitivity and specificity of the immunogenicity assay. Additionally, the observed incidence of any antibody positivity in an assay is highly dependent on several factors, including assay sensitivity and specificity, assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to raxibacumab with the incidence of antibodies to other products may be misleading.

Read the entire FDA prescribing information for Raxibacumab (Human IgG1λ Monoclonal Antibody Intravenous Infusion)


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© Raxibacumab Patient Information is supplied by Cerner Multum, Inc. and Raxibacumab Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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