AnthraxPhase 2NCT04067011
Velocity 2: An Anthrax Vaccine and Antibiotics Clinical Study
A Phase 2 study testing Ciprofloxacin 500Mg Tablet, Doxycycline 100Mg Tablet and AV7909 in people with Anthrax, run by Emergent BioSolutions at 4 sites in United States.
Trial summary
This study is designed to evaluate the pharmacokinetic (PK) profiles of ciprofloxacin or doxycycline when administered orally, prior to, and following, the intramuscular (IM) administration of a two-dose schedule of AV7909 administered two weeks apart. 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?
- Ciprofloxacin 500Mg Tablet, Doxycycline 100Mg Tablet and AV7909
- Type of treatment
- Vaccines, Pill or oral medicine, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 210 participants
- Where
- 4 sitesUnited States
- Study dates
- 12 Aug 2019to 19 Mar 2020
- 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
- Written informed consent obtained from the participant (dated, signed, and captured in the medical chart at the site).
- A male or female, aged 18 to 45 years of age, inclusive, at the time of informed consent.
- Healthy condition as established by medical history and clinical examination before entering into the study.
- Body mass index (BMI) less than or equal to 35.0 kg/m^2 at the Screening visit.
- Have adequate venous access for phlebotomies.
- For a woman of childbearing potential (WOCBP), negative pregnancy test at Screening and pre-randomization on Day 1, not currently breastfeeding, and no intention to become pregnant during the study period through 12 months after last receipt of any investigational product (IP). Every female participant is considered to be a WOCBP unless she is surgically sterile (hysterectomy, bilateral salpingectomy or bilateral oophorectomy) OR postmenopausal (defined as >12 consecutive months without menses and screen follicle-stimulating hormone > 30 mIU/mL). Women who are not of childbearing potential are allowed to enroll if they are surgically sterile or postmenopausal as defined above.
- Female participants randomized to Groups 1 or 2 must be willing to add a double-barrier method, IUD, or abstinence as back-up forms of birth control since ciprofloxacin and doxycycline may decrease the effectiveness of birth control pills, implantable or injectable contraceptives.
Who cannot join
- A Screening clinical laboratory test result greater than the central laboratory's upper limit of normal (ULN) for aspartate aminotransferase (AST), alanine aminotransferase (ALT), random glucose, total bilirubin, blood urea nitrogen (BUN), or creatinine. Other serum chemistry parameters that are not within the reference range will not be considered exclusionary unless deemed clinically significant by the principal investigator.
- History of allergic reaction or intolerance to quinolone antimicrobials or any medical condition that would contraindicate the use of ciprofloxacin, including and not limited to vascular disorders, tendon disorders, certain genetic connective tissue disorders (e.g., Marfan and Ehlers-Danlos syndrome), prolongation of QT interval, seizures, peripheral neuropathy, increased risk of C. difficile infection.
- History of allergic reaction or intolerance to tetracycline antibiotics or any medical condition that would contraindicate the use of doxycycline including an increased risk of C. difficile infection, increases in BUN or an increased sensitivity to direct sunlight or ultraviolet radiation resulting in erythema.
- Has a need for any of the prohibited medications or requires the medications/foods within the prohibited times.
- Have a tattoo/scar/birthmark or any other skin condition affecting the deltoid area that may interfere with injection site assessments.
- History of anthrax disease, suspected exposure to anthrax, or previous vaccination with any anthrax vaccine.
Show all 24Show fewer
- Have previously served in the military any time after 1990 or plan to enlist in the military any time from Screening through the final telephone contact.
- Previous anaphylactic reaction, severe systemic response, or serious hypersensitivity to a prior immunization or a known allergy to synthetic ODNs, aluminum, formaldehyde, benzethonium chloride (phemerol).
- Plan to have an elective surgery at any point during the study until after the final safety phone contact.
- Have donated or plan to donate blood within one month prior to enrollment or at any point during the study until after the final safety phone contact.
- Use of any investigational or non-registered product (drug, vaccine or biologic) within 30 days preceding the dose of study vaccine, or planned use during the study until after the final safety phone contact.
- Planned administration of any commercially-available vaccine from one week prior to the first study vaccination through two weeks after the last vaccination.
- Have experienced chronic dosing (defined as more than 14 days) with any immune-modifying drugs within six months of study enrollment. This includes oral, intramuscular, intra-articular, intravenous, or inhalation corticosteroids except in the case of inhaled or intranasal medications for seasonal allergies.
- Receipt of immunoglobulins and/or any blood products within the three months preceding study enrollment or at any point during the study period until after the final safety visit on Day 51.
- An abnormal electrocardiogram (ECG) at screening interpreted as 'Abnormal, Significant'. Inclusion of participants with 'Abnormal, Insignificant' ECGs will be based on the principal investigator's discretion.
- Have an active malignancy or history of metastatic or hematologic malignancy.
- Have a history of an autoimmune, inflammatory, vasculitic or rheumaticor rheumatic disease including but not limited to systemic lupus erythematosus, Guillain-Barré syndrome, myasthenia gravis, polymyalgia rheumatica, diabetes mellitus type I, rheumatoid arthritis or scleroderma.
- A positive laboratory evidence of hepatitis B, hepatitis C, or human immunodeficiency virus (HIV) HIV-1 or HIV-2 infection.
- Positive result on urine drug screen, any evidence of ongoing drug abuse or dependence (including alcohol), or recent history (over the past five years) of treatment for alcohol or drug abuse.
- Has an acute disease at the time of enrollment.
- Any medical condition that, in the opinion of the investigator, could adversely impact the participant's involvement or the conduct of the study.
- Have a significant chronic condition, e.g., serious cardiovascular, pulmonary, hepatic, type II diabetes mellitus or renal disease that, in the opinion of the investigator, would render treatment unsafe or would interfere with trial evaluations or completion of the study.
- An opinion of the investigator that it would be unwise to allow the participant to be randomized into the study.
- Member or immediate family member of an investigator site team.
Trial locations and contacts
4 sites in 1 country.
United States4 sites
Avail Clinical Research, LLC
DeLand, Florida, 32720
The Center for Pharmaceutical Research
Kansas City, Missouri, 64114
New Orleans Center for Clinical Research / Volunteer Research Group
Knoxville, Tennessee, 37920
Meridian Clinical Research, LLC
Omaha, Nebraska, 68134
About this study
Official title: A Phase 2 Drug-Vaccine Interaction Study to Examine Whether Co-administering AV7909 With Ciprofloxacin or Doxycycline Affects Antibiotic Pharmacokinetics or AV7909 Immunogenicity in Healthy Adults
This study is designed to evaluate the pharmacokinetic (PK) profiles of ciprofloxacin or doxycycline when administered orally, prior to, and following, the intramuscular (IM) administration of a two-dose schedule of AV7909 administered two weeks apart.
Read the detailed description
This is a Phase 2, open-label, multicenter, randomized trial designed to evaluate the pharmacokinetic profile, immunogenicity, and safety of AV7909 and ciprofloxacin or doxycycline when administered concomitantly in healthy adults for an indication of post-exposure prophylaxis (PEP) of anthrax.
Healthy adults between 18 to 45 years of age (inclusive) will sign and date an informed consent form and then be screened for eligibility for participation in the study 2 to 28 days prior to randomization. Participants meeting the entry criteria will be randomized 1:1:1 to one of the three study groups (AV7909 + ciprofloxacin, AV7909 + doxycycline and AV7909 only) on Day 1.
Subjects randomized into Groups 1 \& 2 will be assigned to subgroups. Subgroup A will be assigned to the antibiotic PK treatment group first, while subgroup B will be assigned to the antibiotic non-PK treatment group.
Participants will be evaluated for safety through Day 51 [or the early withdrawal visit (EWV)], as assessed by clinical laboratory tests (hematology, serum chemistry, and urinalysis), monitoring of Adverse Events (AEs) including Serious Adverse Events (SAEs) and Adverse Events of Special Interest (AESIs), vital signs, and physical examinations. Adverse Events of Special Interest are adverse events associated with autoimmune disease as defined by the Center for Biologics Evaluation and Research, and might represent a safety signal for vaccine-associated autoimmunity. Reactogenicity (solicited systemic and injection site reactions) will be assessed daily by the participants using electronic diaries (e-diaries) after each vaccination. The e-diary will also be used to record self-administration of antibiotics for applicable study groups.
Information on the use of medications will be collected at each study visit. In addition, blood samples for auto-antibody assessment will be taken at Day 1 pre-dose and Day 51 (or Early Withdrawal Visit).
Participants who receive at least one dose of vaccine will also be asked to participate in safety follow-up phone calls occurring on Month 3, Month 6, Month 9, and Month 12 (nominally 3, 6, 9, and 12 months after the last vaccination) to collect information on AEs, SAEs and any potential AESIs. Based on responses at these phone contacts, participants may be asked to return to the clinic for an unscheduled visit to provide blood samples for auto-antibody testing to investigate reports of potential AESIs.
Independent safety oversight will be provided by a Data Safety Monitoring Board, which will be notified of significant AEs, potential AEsIs, or any other events as determined by the Medical Monitor, on an ongoing basis.
- Conditions
- Anthrax
- Being tested
- Ciprofloxacin 500Mg Tablet, Doxycycline 100Mg Tablet, AV7909
- Keywords
- Antibiotics, Pharmacokinetics, Vaccine, Ciprofloxacin, Doxycycline, CPG 7909, Bacillus anthracis, Anthrax Vaccine Adsorbed, Post-exposure Prophylaxis, Adjuvant
- Medical subject headings
- Anthrax
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Ciprofloxacin 500Mg TabletDrug
Ciprofloxacin 500mg administered by mouth every 12 hours. The antibiotic will be administered orally on Study Days 4-9, 22-24 and 31-37.
Doxycycline 100Mg TabletDrug
Doxycycline 100mg administered by mouth every 12 hours. The antibiotic will be administered orally on Study Days 2-9, 22-24 and 32-38.
AV7909Biological
0.5mL AVA and 0.25mg CPG 7909 per 0.5mL dose.The vaccine will be administered intramuscularly on Study Days 8 and 23.
| Study group | Role | What they receive |
|---|---|---|
| Group 1:Ciprofloxacin + AV7909 | Experimental | Participants meeting entry criteria will be randomized 1:1:1 to one of three investigational study groups. Groups 1 to 3 will each receive a manufactured lot of AV7909 per the study visit schedule.
Group 1 will concomitantly receive ciprofloxacin. Receives: Drug: Ciprofloxacin 500Mg Tablet; Biological: AV7909 |
| Group 2: Doxycycline +AV7909 | Experimental | Participants meeting entry criteria will be randomized 1:1:1 to one of three investigational study groups. Groups 1 to 3 will each receive a manufactured lot of AV7909 per the study visit schedule.
Group 2 will concomitantly receive doxycycline. Receives: Drug: Doxycycline 100Mg Tablet; Biological: AV7909 |
| Group 3: AV7909 | Experimental | Participants meeting entry criteria will be randomized 1:1:1 to one of three investigational study groups. Groups 1 to 3 will each receive a manufactured lot of AV7909 per the study visit schedule. Receives: Biological: AV7909 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Ratio of Ciprofloxacin Area Under the Curve From 0 to 12 Hours (AUC0-12h) and Maximum Concentration (Cmax) on Days 8 and 35
Based on serum concentrations of ciprofloxacin on Day 8 (pre-AV7909 vaccination) and on Day 35 (post-AV7909 vaccination), steady state AUC0-12h and Cmax were derived, and geometric mean of ratio of AUC0-12h on Day35/Day 8 and geometric mean of ratio for Cmax on Day 35/Day8, and the corresponding 90% CI of the mean ratios were calculated.
Measured: Pre-dose and 0.25, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10 and 12 hours post-ciprofloxacin dose on Days 8 (pre-AV7909 vaccination) and 35 (post-AV7909 vaccination)
Ratio of Doxycycline Area Under the Curve From 0 to 12 Hours (AUC0-12h) and Maximum Concentration (Cmax) on Days 8 and 38
Based on serum concentrations of doxycycline on Day 8 (pre-AV7909 vaccination) and on Day 38 (post-AV7909 vaccination), steady state AUC0-12h and Cmax were derived, and geometric mean of ratio of AUC0-12h on Day38/Day 8 and geometric mean of ratio for Cmax on Day 38/Day8, and the corresponding 90% CI of the mean ratios were calculated.
Measured: Pre-dose and 0.25, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10 and 12 hours post-doxycycline dose on Days 8 (pre-AV7909 vaccination) and 38 (post-AV7909 vaccination)
Secondary outcomes (1)
Geometric Mean TNA 50% Neutralizing Factor (NF50) Values Two Weeks After the Second AV7909 Vaccination (Day 37 ± 1 Day).
Immunogenicity response as assessed by geometric mean of TNA NF50 values at Day 37 (two weeks after second dose of AV7909 vaccination).
Measured: Day 37 ± 1 day
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Aug 2019
- Study start12 Aug 2019
- Primary completion5 Mar 2020
- Study completion19 Mar 2020
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
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 210 participants (actual)
Sponsor and investigators
- Lead sponsor
- Emergent BioSolutions
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- Biomedical Advanced Research and Development Authority
- Responsible party
- Sponsor
- Investigators
- Bojan Drobic, Study director, Emergent BioSolutions
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04067011
- Sponsor's protocol ID
- EBS.AVA.210
- Status last verified
- Aug 2025
- First submitted
- 15 Jul 2019
- Last updated
- 8 Sep 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Publications
Drobic B, Akintunde G, Kim J, Mirceta M, Beach M, Komlenovic V. Effect of Co-administration of the anthrax vaccine adsorbed, adjuvanted with ciprofloxacin or doxycycline on antibiotic pharmacokinetics and the vaccine immunogenicity: A phase 2 drug-vaccine interaction study. Vaccine. 2026 Feb 15;73:128135. doi: 10.1016/j.vaccine.2025.128135. Epub 2025 Dec 24.
PubMed 41447782
Study at a glance
From the registry record, last updated by the sponsor on 8 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2 Drug-Vaccine Interaction Study to Examine Whether Co-administering AV7909 With Ciprofloxacin or Doxycycline Affects Antibiotic Pharmacokinetics or AV7909 Immunogenicity in Healthy Adults
- ClinicalTrials.gov ID
- NCT04067011
- Acronym / sponsor ID
- EBS.AVA.210
- Conditions
- Anthrax
- Keywords
- Antibiotics, Pharmacokinetics, Vaccine, Ciprofloxacin, Doxycycline, CPG 7909, Bacillus anthracis, Anthrax Vaccine Adsorbed
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 210 participants (actual)
- Lead sponsor
- Emergent BioSolutionsIndustry (pharma, biotech, devices)
- Collaborators
- Biomedical Advanced Research and Development Authority
- Study start
- 12 Aug 2019 (actual)
- Primary completion
- 5 Mar 2020 (actual)
- Study completion
- 19 Mar 2020 (actual)
- First posted
- 26 Aug 2019 (actual)
- Results
- Posted 30 Jun 2021
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is designed to evaluate the pharmacokinetic (PK) profiles of ciprofloxacin or doxycycline when administered orally, prior to, and following, the intramuscular (IM) administration of a two-dose schedule of AV7909 administered two weeks apart.
Detailed description
This is a Phase 2, open-label, multicenter, randomized trial designed to evaluate the pharmacokinetic profile, immunogenicity, and safety of AV7909 and ciprofloxacin or doxycycline when administered concomitantly in healthy adults for an indication of post-exposure prophylaxis (PEP) of anthrax.
Healthy adults between 18 to 45 years of age (inclusive) will sign and date an informed consent form and then be screened for eligibility for participation in the study 2 to 28 days prior to randomization. Participants meeting the entry criteria will be randomized 1:1:1 to one of the three study groups (AV7909 + ciprofloxacin, AV7909 + doxycycline and AV7909 only) on Day 1.
Subjects randomized into Groups 1 \& 2 will be assigned to subgroups. Subgroup A will be assigned to the antibiotic PK treatment group first, while subgroup B will be assigned to the antibiotic non-PK treatment group.
Participants will be evaluated for safety through Day 51 [or the early withdrawal visit (EWV)], as assessed by clinical laboratory tests (hematology, serum chemistry, and urinalysis), monitoring of Adverse Events (AEs) including Serious Adverse Events (SAEs) and Adverse Events of Special Interest (AESIs), vital signs, and physical examinations. Adverse Events of Special Interest are adverse events associated with autoimmune disease as defined by the Center for Biologics Evaluation and Research, and might represent a safety signal for vaccine-associated autoimmunity. Reactogenicity (solicited systemic and injection site reactions) will be assessed daily by the participants using electronic diaries (e-diaries) after each vaccination. The e-diary will also be used to record self-administration of antibiotics for applicable study groups.
Information on the use of medications will be collected at each study visit. In addition, blood samples for auto-antibody assessment will be taken at Day 1 pre-dose and Day 51 (or Early Withdrawal Visit).
Participants who receive at least one dose of vaccine will also be asked to participate in safety follow-up phone calls occurring on Month 3, Month 6, Month 9, and Month 12 (nominally 3, 6, 9, and 12 months after the last vaccination) to collect information on AEs, SAEs and any potential AESIs. Based on responses at these phone contacts, participants may be asked to return to the clinic for an unscheduled visit to provide blood samples for auto-antibody testing to investigate reports of potential AESIs.
Independent safety oversight will be provided by a Data Safety Monitoring Board, which will be notified of significant AEs, potential AEsIs, or any other events as determined by the Medical Monitor, on an ongoing basis.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Group 1:Ciprofloxacin + AV7909 | Experimental | Drug: Ciprofloxacin 500Mg Tablet, Biological: AV7909Participants meeting entry criteria will be randomized 1:1:1 to one of three investigational study groups. Groups 1 to 3 will each receive a manufactured lot of AV7909 per the study visit schedule. Group 1 will concomitantly receive ciprofloxacin. |
| Group 2: Doxycycline +AV7909 | Experimental | Drug: Doxycycline 100Mg Tablet, Biological: AV7909Participants meeting entry criteria will be randomized 1:1:1 to one of three investigational study groups. Groups 1 to 3 will each receive a manufactured lot of AV7909 per the study visit schedule. Group 2 will concomitantly receive doxycycline. |
| Group 3: AV7909 | Experimental | Biological: AV7909Participants meeting entry criteria will be randomized 1:1:1 to one of three investigational study groups. Groups 1 to 3 will each receive a manufactured lot of AV7909 per the study visit schedule. |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (7 listed)
- Written informed consent obtained from the participant (dated, signed, and captured in the medical chart at the site).
- A male or female, aged 18 to 45 years of age, inclusive, at the time of informed consent.
- Healthy condition as established by medical history and clinical examination before entering into the study.
- Body mass index (BMI) less than or equal to 35.0 kg/m^2 at the Screening visit.
- Have adequate venous access for phlebotomies.
Key exclusion criteria (24 listed)
- A Screening clinical laboratory test result greater than the central laboratory's upper limit of normal (ULN) for aspartate aminotransferase (AST), alanine aminotransferase (ALT), random glucose, total bilirubin, blood urea nitrogen (BUN), or creatinine. Other serum chemistry parameters that are not within the reference range will not be considered exclusionary unless deemed clinically significant by the principal investigator.
- History of allergic reaction or intolerance to quinolone antimicrobials or any medical condition that would contraindicate the use of ciprofloxacin, including and not limited to vascular disorders, tendon disorders, certain genetic connective tissue disorders (e.g., Marfan and Ehlers-Danlos syndrome), prolongation of QT interval, seizures, peripheral neuropathy, increased risk of C. difficile infection.
- History of allergic reaction or intolerance to tetracycline antibiotics or any medical condition that would contraindicate the use of doxycycline including an increased risk of C. difficile infection, increases in BUN or an increased sensitivity to direct sunlight or ultraviolet radiation resulting in erythema.
- Has a need for any of the prohibited medications or requires the medications/foods within the prohibited times.
- Have a tattoo/scar/birthmark or any other skin condition affecting the deltoid area that may interfere with injection site assessments.
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 |
|---|---|---|
| Ciprofloxacin 500Mg TabletCiprofloxacin 500mg administered by mouth every 12 hours. The antibiotic will be administered orally on Study Days 4-9, 22-24 and 31-37. | Drug | Group 1:Ciprofloxacin + AV7909 |
| Doxycycline 100Mg TabletDoxycycline 100mg administered by mouth every 12 hours. The antibiotic will be administered orally on Study Days 2-9, 22-24 and 32-38. | Drug | Group 2: Doxycycline +AV7909 |
| AV79090.5mL AVA and 0.25mg CPG 7909 per 0.5mL dose.The vaccine will be administered intramuscularly on Study Days 8 and 23. | Biological | Group 1:Ciprofloxacin + AV7909, Group 2: Doxycycline +AV7909, Group 3: AV7909 |
Primary outcome
Ratio of Ciprofloxacin Area Under the Curve From 0 to 12 Hours (AUC0-12h) and Maximum Concentration (Cmax) on Days 8 and 35
Time frame: Pre-dose and 0.25, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10 and 12 hours post-ciprofloxacin dose on Days 8 (pre-AV7909 vaccination) and 35 (post-AV7909 vaccination)
Based on serum concentrations of ciprofloxacin on Day 8 (pre-AV7909 vaccination) and on Day 35 (post-AV7909 vaccination), steady state AUC0-12h and Cmax were derived, and geometric mean of ratio of AUC0-12h on Day35/Day 8 and geometric mean of ratio for Cmax on Day 35/Day8, and the corresponding 90% CI of the mean ratios were calculated.
Ratio of Doxycycline Area Under the Curve From 0 to 12 Hours (AUC0-12h) and Maximum Concentration (Cmax) on Days 8 and 38
Time frame: Pre-dose and 0.25, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10 and 12 hours post-doxycycline dose on Days 8 (pre-AV7909 vaccination) and 38 (post-AV7909 vaccination)
Based on serum concentrations of doxycycline on Day 8 (pre-AV7909 vaccination) and on Day 38 (post-AV7909 vaccination), steady state AUC0-12h and Cmax were derived, and geometric mean of ratio of AUC0-12h on Day38/Day 8 and geometric mean of ratio for Cmax on Day 38/Day8, and the corresponding 90% CI of the mean ratios were calculated.
1 secondary outcome
Geometric Mean TNA 50% Neutralizing Factor (NF50) Values Two Weeks After the Second AV7909 Vaccination (Day 37 ± 1 Day).
Time frame: Day 37 ± 1 day
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 8 Sep 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 41447782Drobic B, Akintunde G, Kim J, Mirceta M, Beach M, Komlenovic V. Effect of Co-administration of the anthrax vaccine adsorbed, adjuvanted with ciprofloxacin or doxycycline on antibiotic pharmacokinetics and the vaccine immunogenicity: A phase 2 drug-vaccine interaction study. Vaccine. 2026 Feb 15;73:128135. doi: 10.1016/j.vaccine.2025.128135. Epub 2025 Dec 24.
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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.
Bojan Drobic study director
Emergent BioSolutions
4 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 Ciprofloxacin 500Mg Tablet, Doxycycline 100Mg Tablet and AV7909 in people with Anthrax, run by Emergent BioSolutions at 4 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 7 inclusion and 24 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 8 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 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 30 Jun 2021). 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?
Ratio of Ciprofloxacin Area Under the Curve From 0 to 12 Hours (AUC0-12h) and Maximum Concentration (Cmax) on Days 8 and 35 (time frame: Pre-dose and 0.25, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10 and 12 hours post-ciprofloxacin dose on Days 8 (pre-AV7909 vaccination) and 35 (post-AV7909 vaccination)). The study lists 2 primary outcomes in all. 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 NCT04067011, 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 8 Sep 2025.