A Phase 2 interventional study of BioThrax and Ciprofloxacin in Anthrax, sponsored by Emergent BioSolutions. Completed at 3 sites in United States. Open to participants aged 18 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-06-15.
Sponsored by Emergent BioSolutions · Phase 2, Interventional, and Treatment
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).
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)
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.
75 studies on the registry are indexed under Anthrax; 12 are open to participants now.
This study's enrollment of 154 is above the median of 100 across 57 interventional studies indexed under Anthrax.
Browse Anthrax studies →Emergent BioSolutions is the lead sponsor of 47 studies on the registry; 7 are open to participants now.
Of its 11 completed or terminated interventional studies of FDA-regulated products, 7 (64%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Live vaccines
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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).
Biological: BioThrax · Drug: Ciprofloxacin
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).
Biological: BioThrax · Drug: Ciprofloxacin
BioThrax: route of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule.
Biological: BioThrax
route of administration/schedule- 0.5 mL subcutaneous (SC) injection / 0-2-4 week schedule
Also known as: Anthrax Vaccine Adsorbed, AVA
500 mg twice a day (Days 1-6, 19-21, 33-35, 40-48).
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).
Time frame: Day 5 and Day 44 in Arm 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.
Time frame: Two weeks after last vaccination
Subjects were enrolled from 14 Dec 2012 to 04 Aug 2013 at 3 US sites.
| Milestone | BioThrax + Ciprofloxacin PK | BioThrax + Ciprofloxacin no PK | BioThrax Only |
|---|---|---|---|
| Started | 44 | 40 | 70 |
| Treated | 38 | 39 | 67 |
| Completed | 32 | 25 | 56 |
| Not completed | 12 | 15 | 14 |
| Withdrew: Lost to follow-up | 3 | 6 | 8 |
| Withdrew: Withdrawal by subject | 6 | 5 | 6 |
| Withdrew: Subject non-compliant | 3 | 3 | 0 |
| Withdrew: Used excluded drug | 0 | 1 | 0 |
Ratios of Area Under the Curve from zero to 12 hours (AUC0-12h) and maximum concentration (Cmax) achieved for ciprofloxacin (Day 5/Day 44).
| ratio | Arm 1 = BioThrax (0.5 mL) + Ciprofloxacin (500 mg Bid) + PK |
|---|---|
| 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) |
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.
| titer | BioThrax + Ciprofloxacin (Arms 1 + 2) | BioThrax Only (Arm 3) |
|---|---|---|
| Geometric Mean Titer (GMT) of Toxin Neutralizing Antibody (TNA) Levels | 1.170 (0.912 to 1.500) | 0.923 (0.723 to 1.780) |
Collected over 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.. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| BioThrax + Ciprofloxacin PK | — | 0/38 (0%) | 6/38 (15.8%) |
| BioThrax + Ciprofloxacin no PK | — | 0/39 (0%) | 7/39 (17.9%) |
| BioThrax Only | — | 0/67 (0%) | 14/67 (20.9%) |
| Event | BioThrax + Ciprofloxacin PK | BioThrax + Ciprofloxacin no PK | BioThrax Only |
|---|---|---|---|
| HeadacheNervous system disorders | 3/38 | 4/39 | 4/67 |
| NauseaGastrointestinal disorders | 1/38 | 1/39 | 5/67 |
| MyalgiaMusculoskeletal and connective tissue disorders | 0/38 | 0/39 | 5/67 |
| Injection site massGeneral disorders | 0/38 | 0/39 | 4/67 |
| Injection site painGeneral disorders | 0/38 | 0/39 | 4/67 |
| Injection site erythemaGeneral disorders | 2/38 | 0/39 | 2/67 |
| ArthralgiaMusculoskeletal and connective tissue disorders | 2/38 | 0/39 | 1/67 |
| FatigueGeneral disorders | 0/38 | 2/39 | 3/67 |
| Upper respiratory tract infectionInfections and infestations | 1/38 | 2/39 | 3/67 |
Intent to treat population: all subjects who were randomized.
| Age, Continuous(years) | BioThrax + Ciprofloxacin PK | BioThrax + Ciprofloxacin no PK | BioThrax Only | Total |
|---|---|---|---|---|
| Mean | 30.5 ± 8.76 | 30.8 ± 8.05 | 30.2 ± 7.29 | 30.4 ± 7.88 |
| Age, Customized(participants) | BioThrax + Ciprofloxacin PK | BioThrax + Ciprofloxacin no PK | BioThrax Only | Total |
|---|---|---|---|---|
| 18 - 30 years | 22 | 20 | 35 | 77 |
| 31 - 45 years | 22 | 20 | 35 | 77 |
| Sex: Female, Male(Participants) | BioThrax + Ciprofloxacin PK | BioThrax + Ciprofloxacin no PK | BioThrax Only | Total |
|---|---|---|---|---|
| Female | 20 | 20 | 36 | 76 |
| Male | 24 | 20 | 34 | 78 |
| Race/Ethnicity, Customized(participants) | BioThrax + Ciprofloxacin PK | BioThrax + Ciprofloxacin no PK | BioThrax Only | Total |
|---|---|---|---|---|
| White | 24 | 22 | 33 | 79 |
| Black or African America | 20 | 14 | 34 | 68 |
| Asian | 0 | 2 | 1 | 3 |
| American Indian or Alaskan Native | 0 | 1 | 2 | 3 |
| Multiple | 0 | 1 | 0 | 1 |
This study is completed, as verified in May 2025. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Biothrax