AnthraxPhase 2NCT01753115

Ciprofloxacin BioThrax Co-Administration Study

A Phase 2 study testing BioThrax and Ciprofloxacin in people with Anthrax, run by Emergent BioSolutions at 3 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

The purpose of this clinical trial is to determine whether there is any effect on the antibiotic, ciprofloxacin when taken before and after administration of a 3-dose series of BioThrax® (Anthrax Vaccine Adsorbed or AVA). Read more about this study

Who is it for?: Ages 18 to 45 yearsHealthy volunteers can take part
Conditions the study is for: Anthrax
What is being tested?: BioThrax and Ciprofloxacin
Type of treatment: Vaccines, Injection or infusion
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 154 participants
Where: 3 sitesUnited States
Study dates: Dec 2012to Aug 2013
Phase: Phase 2
Are there results?: Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 to 45 years
All sexes
Healthy volunteers accepted
Adult

Who may be able to join

Be between 18 and 45 years of age, at the time of enrollment
Be in good health as determined by the investigator from medical history and a physical examination.
If a pre-menopausal female, must be using acceptable methods of birth control.
Be willing and able to return for all follow-up visits and blood and urine collections for the duration of the trial
Be willing and able to complete a web-enabled electronic diary and report concomitant medications, adverse events, and BioThrax reactogenicity events during the trial
Be able to understand and communicate in English.

Who cannot join

Prior immunization with anthrax vaccine or known exposure to anthrax organisms
Intend to enlist in the military during the study.
Have a known allergy to aluminum hydroxide, formaldehyde, benzethonium chloride, or latex.
Plan to receive experimental products 30 days prior to study entry or at any time during the study
Have received a live vaccine in the 30 days before study entry
Plan to receive a live vaccine at any time during the study.

Show all 11Show fewer

Have ongoing drug abuse/dependence (including alcohol) issues and/or test positive in a urine drug screen for amphetamines, barbiturates, cocaine or opiates
Have received immunosuppressive therapy (including systemic steroids) within 30 days prior to trial entry
Have any other condition known to produce or be associated with immunosuppression
Have received cytotoxic therapy in the previous 5 years
A chronic condition that, in the opinion of the Investigator, would render vaccination unsafe or would interfere with trial evaluations or completion of the study.

Trial locations and contacts

3 sites in 1 country.

United States3 sites

Research Across America
Dallas, Texas, 75234
The Center for Pharmaceutical Research
Kansas City, Missouri, 64114
Meridian Clinical Research
Omaha, Nebraska, 68134

Other trials in United States

About this study

Official title: A Study of The Effects of Co-Administering Ciprofloxacin and BioThrax on the Pharmacokinetics of Ciprofloxacin in Healthy Adults

This study will be conducted in the United States (US) in 154 healthy male and female volunteer subjects ages 18 to 45.

The duration of study participation for each subject will be approximately 76 days (approximately 2.5 months)

Read the detailed description

BioThrax is the only FDA-licensed vaccine for the prevention of anthrax infection. This is a randomized, open-label, Phase 2, multi-center trial to investigate the potential interactions of ciprofloxacin and BioThrax.

Conditions: Anthrax
Being tested: BioThrax, Ciprofloxacin
Keywords: post-exposure prophylaxis, toxin neutralization assay
Medical subject headings: Anthrax

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

BioThraxBiological
Also called Anthrax Vaccine Adsorbed, AVA
route of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule
CiprofloxacinDrug
500 mg twice a day (Days 1-6, 19-21, 33-35, 40-48).

Study groups in NCT01753115
Study group	Role	What they receive
BioThrax + Ciprofloxacin PK	Experimental	BioThrax: route of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule. Ciprofloxacin: 500 mg twice a day (Days 1-6, 19-21, 33-35, 40-48). Receives: Biological: BioThrax; Drug: Ciprofloxacin
BioThrax + Ciprofloxacin no PK	Experimental	BioThrax: route of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule. Ciprofloxacin: 500 mg twice a day (Days 1-6, 19-21, 33-35, 40-48). Receives: Biological: BioThrax; Drug: Ciprofloxacin
BioThrax only	Experimental	BioThrax: route of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule. Receives: Biological: BioThrax

What is being measured

The primary outcome is the main question the study is designed to answer.

Ratios of Ciprofloxacin Area Under the Curve and Cmax (Day 5/Day 44)
Ratios of Area Under the Curve from zero to 12 hours (AUC0-12h) and maximum concentration (Cmax) achieved for ciprofloxacin (Day 5/Day 44).
Measured: Day 5 and Day 44 in Arm 1

Secondary outcomes (1)

Geometric Mean Titer (GMT) of Toxin Neutralizing Antibody (TNA) Levels
Blood was collected in arms 1 and 2 at day 48 ( 2 weeks following last vaccination) and in arm 3 at day 43 ( 2 weeks following last vaccination) for TNA assay to determine the NF50 antibody titer for calculating GMT.
Measured: Two weeks after last vaccination

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

Dec 2012Aug 2013

First posted20 Dec 2012 (estimated)
Study startDec 2012
Primary completionAug 2013
Study completionAug 2013

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (1)Papers the sponsor has linked to this study.
Other trials for AnthraxStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 2
Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Masking: None (open label)
Enrolment: 154 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT01753115
Sponsor's protocol ID: EBS.AVA.009
Status last verified: May 2025
First submitted: 14 Dec 2012
Last updated: 15 Jun 2025
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No

Publications

Cassie D, Longstreth J, Hopkins R, Hunter-Stitt E, Drobic B, Bellani M. Compatible co-administration of BioThrax(R) vaccine and ciprofloxacin-Results of a randomized open-label drug-vaccine interaction trial. Vaccine X. 2024 Jan 7;17:100431. doi: 10.1016/j.jvacx.2024.100431. eCollection 2024 Mar.
PubMed 38352727

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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All Anthrax trials

Study at a glance

From the registry record, last updated by the sponsor on 15 Jun 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Study of The Effects of Co-Administering Ciprofloxacin and BioThrax on the Pharmacokinetics of Ciprofloxacin in Healthy Adults
ClinicalTrials.gov ID: NCT01753115
Acronym / sponsor ID: EBS.AVA.009
Conditions: Anthrax
Keywords: post-exposure prophylaxis, toxin neutralization assay
Phase: Phase 2
Study type: Interventional
Recruitment status: Completed
Enrolment: 154 participants (actual)
Lead sponsor: Emergent BioSolutionsIndustry (pharma, biotech, devices)
Collaborators: Department of Health and Human Services
Study start: Dec 2012
Primary completion: Aug 2013 (actual)
Study completion: Aug 2013 (actual)
First posted: 20 Dec 2012 (estimated)
Results: Posted 19 Nov 2014

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

This study will be conducted in the United States (US) in 154 healthy male and female volunteer subjects ages 18 to 45.

The duration of study participation for each subject will be approximately 76 days (approximately 2.5 months)

Detailed description

Study design

Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Masking: None (open label)
Number of arms: 3

Arm	Type	Receives
BioThrax + Ciprofloxacin PK	Experimental	Biological: BioThrax, Drug: CiprofloxacinBioThrax: route of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule. Ciprofloxacin: 500 mg twice a day (Days 1-6, 19-21, 33-35, 40-48).
BioThrax + Ciprofloxacin no PK	Experimental	Biological: BioThrax, Drug: CiprofloxacinBioThrax: route of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule. Ciprofloxacin: 500 mg twice a day (Days 1-6, 19-21, 33-35, 40-48).
BioThrax only	Experimental	Biological: BioThraxBioThrax: route of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule.

Who may qualify

Ages: 18 to 45 years
Sex: All
Healthy volunteers: Accepted
Age groups: Adult

Key inclusion criteria (6 listed)

Be between 18 and 45 years of age, at the time of enrollment
Be in good health as determined by the investigator from medical history and a physical examination.
If a pre-menopausal female, must be using acceptable methods of birth control.
Be willing and able to return for all follow-up visits and blood and urine collections for the duration of the trial
Be willing and able to complete a web-enabled electronic diary and report concomitant medications, adverse events, and BioThrax reactogenicity events during the trial

Key exclusion criteria (11 listed)

Prior immunization with anthrax vaccine or known exposure to anthrax organisms
Intend to enlist in the military during the study.
Have a known allergy to aluminum hydroxide, formaldehyde, benzethonium chloride, or latex.
Plan to receive experimental products 30 days prior to study entry or at any time during the study
Have received a live vaccine in the 30 days before study entry

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
BioThraxAlso: Anthrax Vaccine Adsorbed, AVAroute of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule	Biological	BioThrax + Ciprofloxacin PK, BioThrax + Ciprofloxacin no PK, BioThrax only
Ciprofloxacin500 mg twice a day (Days 1-6, 19-21, 33-35, 40-48).	Drug	BioThrax + Ciprofloxacin PK, BioThrax + Ciprofloxacin no PK

Primary outcome

Ratios of Ciprofloxacin Area Under the Curve and Cmax (Day 5/Day 44)
Time frame: Day 5 and Day 44 in Arm 1
Ratios of Area Under the Curve from zero to 12 hours (AUC0-12h) and maximum concentration (Cmax) achieved for ciprofloxacin (Day 5/Day 44).

1 secondary outcome

Geometric Mean Titer (GMT) of Toxin Neutralizing Antibody (TNA) Levels
Time frame: Two weeks after last vaccination

Results and safety

Results posted to the registry on 19 Nov 2014, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
BioThrax + Ciprofloxacin PK	44	32
BioThrax + Ciprofloxacin no PK	40	25
BioThrax Only	70	56

Primary outcome: Ratios of Ciprofloxacin Area Under the Curve and Cmax (Day 5/Day 44)

Time frame: Day 5 and Day 44 in Arm 1. Mean (90% Confidence Interval). Unit: ratio

Measure	Arm 1 = BioThrax (0.5 mL) + Ciprofloxacin (500 mg Bid) + PK n = 32
Ratio Cmax Day 44/Day 5	0.944 (0.852 to 1.046)
Ratio AUC0-12hr Day 44/Day 5	0.887 (0.831 to 0.948)

Arm 1 = BioThrax (0.5 mL) + Ciprofloxacin (500 mg Bid) + PK: Ratio of AUC: 0.887 (90% CI 0.831 to 0.948)
Arm 1 = BioThrax (0.5 mL) + Ciprofloxacin (500 mg Bid) + PK: Ratio of Cmax: 0.944 (90% CI 0.852 to 1.046)

Population analysed: Per protocol population: all subjects in arm 1 who received any dose of ciprofloxacin, had adequate PK data on Day 5 and Day 44, had received all three BioThrax doses, and who had no key protocol deviations (e.g., insufficient blood sample) that would be expected to affect the ciprofloxacin PK assessment.

1 secondary outcome is reported in the full results.

Adverse events

Time frame: Arm 1: enrollment, Days 0-5, 20, 34, 39-44, 48, or the early withdrawal visit (EWV) for a max of 16 visits. Arm 2: enrollment, Days 1, 5, 20, 34, 48, or EWV for a max of 6 visits. Arm 3: enrollment, Days 1, 15, 29, 43, or EWV for a max of 5 visits.. Other adverse events reported at 5% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
BioThrax + Ciprofloxacin PK	0 of 38 (0%)	6 of 38 (15.8%)	Not reported
BioThrax + Ciprofloxacin no PK	0 of 39 (0%)	7 of 39 (17.9%)	Not reported
BioThrax Only	0 of 67 (0%)	14 of 67 (20.9%)	Not reported

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 15 Jun 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Results publication: PubMed 38352727Cassie D, Longstreth J, Hopkins R, Hunter-Stitt E, Drobic B, Bellani M. Compatible co-administration of BioThrax(R) vaccine and ciprofloxacin-Results of a randomized open-label drug-vaccine interaction trial. Vaccine X. 2024 Jan 7;17:100431. doi: 10.1016/j.jvacx.2024.100431. eCollection 2024 Mar.

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Robert Hopkins, MD, MPH, TM principal investigator

Emergent BioSolutions Inc.

3 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing BioThrax and Ciprofloxacin in people with Anthrax, run by Emergent BioSolutions at 3 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 6 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 15 Jun 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 3 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 19 Nov 2014). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Ratios of Ciprofloxacin Area Under the Curve and Cmax (Day 5/Day 44) (time frame: Day 5 and Day 44 in Arm 1). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT01753115, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Jun 2025.