Orthopoxviral DiseasePhase 1NCT00728689

Phase I Trial of an Investigational Small Pox Medication

A Phase 1 study testing ST-246 Days 1 - 3 and ST-246 Days 11 - 13 in people with Orthopoxviral Disease and Smallpox, run by SIGA Technologies at 1 site 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 study was to evaluate the pharmacokinetic parameters and safety of a single dose of ST-246 400mg Form I versus ST-246 400mg Form V capsules in fed normal healthy volunteers. Read more about this study

Who is it for?: Ages 18 to 50 yearsHealthy volunteers can take part
Conditions the study is for: Orthopoxviral Disease, Smallpox, Monkey Pox
What is being tested?: ST-246 Days 1 - 3 and ST-246 Days 11 - 13
Type of treatment: Pill or oral medicine
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 12 participants
Where: 1 siteUnited States
Study dates: Aug 2008to Oct 2008
Phase: Phase 1
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 50 years
All sexes
Healthy volunteers accepted
Adult

Who may be able to join

18 to 50 years
Available for clinical follow-up duration of study.
Able/willing to give written consent.
Good general health; no clinically significant medical history.
Refrain from taking any medications from screening through 72 hours after last dose.
Adequate venous access.

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PE and lab results without clinically significant findings within 28 days prior to receipt of drug.
Meet Lab Criteria within 28 days prior to receipt of drug.
Negative pregnancy test
Non smokers
No alcohol or caffeine
Participant or partner has undergone surgical sterilization, or the participant agrees either to be abstinent or use two non-hormonal methods of contraception for duration of the study

Who cannot join

Marked baseline prolongation of QT/corrected QT interval (QTc) interval (
History of additional risk factors for Torsade de Pointes
Clinically significant abnormal ECG
Personal history of cardiac disease, symptomatic or asymptomatic arrhythmias, syncopal episodes, or prolongation of the PR interval
Family history of Sudden Cardiac Death not clearly due to acute myocardial infarction.
History of any clinically significant conditions including:

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Asthma
Diabetes mellitus
History of thyroidectomy or thyroid disease
Serious angioedema episodes
Head trauma resulting in a diagnosis of TBI other than concussion
Seizure or history of seizure
Bleeding disorder diagnosed by a doctor or significant bruising or bleeding difficulties with intramuscular injections or blood draws
Malignancy
Family history of idiopathic seizures
History or presence of neutropenia or other blood dyscrasia
Known Hepatitis B or Hepatitis C infection
Known human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome illness.
Current or recent history of a clinically significant bacterial, fungal, or mycobacterial infection.
Known clinically significant chronic viral infection (or current clinically significant viral infection
History of frequent or severe headaches or migraines
Known chronic bacterial, mycobacterial, fungal, parasitic, or protozoal infection
Woman who is pregnant or is breast-feeding or planning to become pregnant
On any concomitant medications
History of drug allergy that, in the opinion of the PI, contraindicates participation in the trial.
Inability to swallow medication
Body Mass Index above 35 or below 18,
Current drug abuse or alcohol abuse.
Inability to refrain from physical exercise for a period of 24 hr before and after a PK day or refrain from consuming xanthines, grapefruit or grapefruit juice
Clinically significant lactose intolerance
Received experimental drug within 30 days
Vaccination within 30 days
Total of more than 350 milliliters (mL) of blood drawn in 2 months
Treatment with any immunosuppressant or immunomodulatory medication in 3 months
Any condition occupational reason or other responsibility that, in the judgment of the PI, would jeopardize the safety or rights of a subject participating in the trial or would render the subject unable to comply with the protocol
History or diagnosis that would affect absorption of study medication

Trial locations and contacts

1 site in 1 country.

United States1 site

Orlando Clinical Research Center
Orlando, Florida, 32809

Other trials in United States

About this study

Official title: A Phase I Randomized, Double-Blind, Crossover, Exploratory Study of the Pharmacokinetics of a Single Oral Dose of Form I Versus Form V Capsules of the Anti-Orthopoxvirus Compound ST-246® in Fed Normal Healthy Volunteers

The purpose of this study was to evaluate the pharmacokinetic parameters and safety of a single dose of ST-246 400mg Form I versus ST-246 400mg Form V capsules in fed normal healthy volunteers.

Read the detailed description

This was a Phase I, double-blind, cross-over, single-dose study of the orally administered anti-orthopoxvirus compound, ST-246, to 12 healthy, fed volunteers between the ages of 18 and 50 years. Subjects were randomized such that 6 subjects received either ST-246 Form I (monohydrate) followed 10 days later after a wash-out period by Form V (hemihydrate), and 6 subjects received ST-246 Form V followed by Form I, as for the previous group.

Both forms of ST-246 were similar in the way they were manufactured. The only difference between Form I and Form V may be related to how it dissolves, and this may affect the way that it is absorbed in the human body. Information about any side-effects that may occur will also be collected in this study.

Conditions: Orthopoxviral Disease, Smallpox, Monkey Pox
Being tested: ST-246 Days 1 - 3, ST-246 Days 11 - 13
Keywords: Orthopoxviral, Smallpox, Monkey pox
Medical subject headings: Smallpox, Mpox, Monkeypox

What participants receive

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

ST-246 Days 1 - 3Drug
Also called Tecovirimat
First Intervention is on Days 1 - 3, and includes 6 patients dosed once orally with ST-246 Form I (Arm 1), and 6 patients dosed once orally with ST-246 Form V (Arm 2).
ST-246 Days 11 - 13Drug
Also called Tecovirimat
Second Intervention is on Days 11 - 13 (after a 3 day post-treatment monitoring and 7 day wash-out period) where the 6 patients previously given ST-246 Form I (Arm 1) are now dosed once orally with ST-246 Form V, and the 6 patients previously given ST-246 Form V (Arm 2) are now dosed once orally with ST-246 Form I.

Study groups in NCT00728689
Study group	Role	What they receive
Group ST-246 Form I (followed by Form V)	Active comparator	Each of six subjects receive a single oral 400 mg dose (2×200 mg) of ST-246 Form I (monohydrate) in the first intervention period, followed 10 days later (3 days post-treatment monitoring and 7 days wash-out period) in the second intervention period by a single oral 400 mg dose (2×200 mg) of ST-246 Form V (hemihydrate). Both forms of drug are orally administered within 30 minutes after a standard light meal consisting of 400-450 calories and approximately 25% fat. Receives: Drug: ST-246 Days 1 - 3; Drug: ST-246 Days 11 - 13
Group ST-246 Form V (followed by Form I)	Active comparator	Each of six subjects receive a single oral 400 mg dose (2×200 mg) of ST-246 Form V (hemihydrate) in the first intervention period, followed 10 days later (3 days post-treatment monitoring and 7 days wash-out period) in the second intervention period by a single oral 400 mg dose (2×200 mg) of ST-246 Form I (monohydrate). Both forms of drug are orally administered within 30 minutes after a standard light meal consisting of 400-450 calories and approximately 25% fat. Receives: Drug: ST-246 Days 1 - 3; Drug: ST-246 Days 11 - 13

What is being measured

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

Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: t½
Mean terminal half-life (t½; hrs) for Forms I and V were calculated from [plasma] vs time profiles.
Measured: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs
Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: AUC0-τ
Area under the drug concentration-time curve from time zero to time t, where t is the last timepoint with a drug concentration ≥ lowest obtainable quantification (AUC0-τ; ng*hr/mL).
Measured: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs
Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: AUC0-∞
Area under the drug concentration-time curve from time zero to infinity (AUC0-∞; ng*hr/mL).
Measured: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs
Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: Cmax
Maximum drug concentration in plasma, determined directly from individual concentration-time data (Cmax)
Measured: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs
Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: Tmax
Time to maximum plasma concentration(Tmax; hrs) for Forms I and V were calculated from [plasma] vs time profiles.
Measured: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs

Secondary outcomes (1)

Number of Study Participants Who Tolerated a Single Dose of ST-246 Form I vs. Form V as Determined by No Clinically Significant Changes in Safety Parameters
Evaluated safety parameters included:
1. physical examination/vital signs
2. electrocardiograms (heart rate, PR interval, QRS duration, QT interval, and QTc Bazett)
3. laboratory safety tests (hematology, chemistry, urinalysis)
4. adverse events For a), b) and c), summary statistics (mean,SD, median, minm, maxm)for values, and changes from baseline(Day 1 pre-dose) to each timepoint, were measured and compared to laboratory normal reference ranges. Values for a)- d) were assigned grades according to DAIDS AE Grading Table. Any Grade of 3 or higher was considered severe and significant.
Measured: 4 weeks

Timeline

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

Aug 2008Oct 2008

First posted6 Aug 2008 (estimated)
Study startAug 2008
Primary completionOct 2008
Study completionOct 2008

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 Orthopoxviral DiseaseStudies 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 1
Primary purpose: Treatment
Allocation: Randomised
Intervention model: Crossover
Masking: Triple blind
Who is masked: Participant, Care provider, Investigator
Enrolment: 12 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT00728689
Sponsor's protocol ID: SIGA-246-005
Other IDs: HHSN266200600014C
Status last verified: Sep 2010
First submitted: 1 Aug 2008
Last updated: 1 Oct 2026
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: Yes

Publications

Hatmal MM, Al-Hatamleh MAI, Olaimat AN, Ahmad S, Hasan H, Ahmad Suhaimi NA, Albakri KA, Abedalbaset Alzyoud A, Kadir R, Mohamud R. Comprehensive literature review of monkeypox. Emerg Microbes Infect. 2022 Dec;11(1):2600-2631. doi: 10.1080/22221751.2022.2132882.
PubMed 36263798

Study at a glance

From the registry record, last updated by the sponsor on 1 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Phase I Randomized, Double-Blind, Crossover, Exploratory Study of the Pharmacokinetics of a Single Oral Dose of Form I Versus Form V Capsules of the Anti-Orthopoxvirus Compound ST-246® in Fed Normal Healthy Volunteers
ClinicalTrials.gov ID: NCT00728689
Acronym / sponsor ID: SIGA-246-005
Conditions: Orthopoxviral Disease, Smallpox, Monkey Pox
Keywords: Orthopoxviral, Smallpox, Monkey pox
Phase: Phase 1
Study type: Interventional
Recruitment status: Completed
Enrolment: 12 participants (actual)
Lead sponsor: SIGA TechnologiesIndustry (pharma, biotech, devices)
Collaborators: National Institutes of Health (NIH)
Study start: Aug 2008
Primary completion: Oct 2008 (actual)
Study completion: Oct 2008 (actual)
First posted: 6 Aug 2008 (estimated)
Results: Posted 9 Feb 2010

Clinical summary

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

The purpose of this study was to evaluate the pharmacokinetic parameters and safety of a single dose of ST-246 400mg Form I versus ST-246 400mg Form V capsules in fed normal healthy volunteers.

Detailed description

Study design

Primary purpose: Treatment
Allocation: Randomised
Intervention model: Crossover
Masking: Triple blind (participant, care provider, investigator)
Number of arms: 2

Arm	Type	Receives
Group ST-246 Form I (followed by Form V)	Active comparator	Drug: ST-246 Days 1 - 3, Drug: ST-246 Days 11 - 13Each of six subjects receive a single oral 400 mg dose (2×200 mg) of ST-246 Form I (monohydrate) in the first intervention period, followed 10 days later (3 days post-treatment monitoring and 7 days wash-out period) in the second intervention period by a single oral 400 mg dose (2×200 mg) of ST-246 Form V (hemihydrate). Both forms of drug are orally administered within 30 minutes after a standard light meal consisting of 400-450 calories and approximately 25% fat.
Group ST-246 Form V (followed by Form I)	Active comparator	Drug: ST-246 Days 1 - 3, Drug: ST-246 Days 11 - 13Each of six subjects receive a single oral 400 mg dose (2×200 mg) of ST-246 Form V (hemihydrate) in the first intervention period, followed 10 days later (3 days post-treatment monitoring and 7 days wash-out period) in the second intervention period by a single oral 400 mg dose (2×200 mg) of ST-246 Form I (monohydrate). Both forms of drug are orally administered within 30 minutes after a standard light meal consisting of 400-450 calories and approximately 25% fat.

Who may qualify

Ages: 18 to 50 years
Sex: All
Healthy volunteers: Accepted
Age groups: Adult

Key inclusion criteria (12 listed)

18 to 50 years
Available for clinical follow-up duration of study.
Able/willing to give written consent.
Good general health; no clinically significant medical history.
Refrain from taking any medications from screening through 72 hours after last dose.

Key exclusion criteria (36 listed)

Marked baseline prolongation of QT/corrected QT interval (QTc) interval (
History of additional risk factors for Torsade de Pointes
Clinically significant abnormal ECG
Personal history of cardiac disease, symptomatic or asymptomatic arrhythmias, syncopal episodes, or prolongation of the PR interval
Family history of Sudden Cardiac Death not clearly due to acute myocardial infarction.

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
ST-246 Days 1 - 3Also: TecovirimatFirst Intervention is on Days 1 - 3, and includes 6 patients dosed once orally with ST-246 Form I (Arm 1), and 6 patients dosed once orally with ST-246 Form V (Arm 2).	Drug	Group ST-246 Form I (followed by Form V), Group ST-246 Form V (followed by Form I)
ST-246 Days 11 - 13Also: TecovirimatSecond Intervention is on Days 11 - 13 (after a 3 day post-treatment monitoring and 7 day wash-out period) where the 6 patients previously given ST-246 Form I (Arm 1) are now dosed once orally with ST-246 Form V, and the 6 patients previously given ST-246 Form V (Arm 2) are now dosed once orally with ST-246 Form I.	Drug	Group ST-246 Form I (followed by Form V), Group ST-246 Form V (followed by Form I)

Primary outcome

Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: t½
Time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs
Mean terminal half-life (t½; hrs) for Forms I and V were calculated from [plasma] vs time profiles.
Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: AUC0-τ
Time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs
Area under the drug concentration-time curve from time zero to time t, where t is the last timepoint with a drug concentration ≥ lowest obtainable quantification (AUC0-τ; ng*hr/mL).
Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: AUC0-∞
Time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs
Area under the drug concentration-time curve from time zero to infinity (AUC0-∞; ng*hr/mL).
Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: Cmax
Time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs
Maximum drug concentration in plasma, determined directly from individual concentration-time data (Cmax)
Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: Tmax
Time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs
Time to maximum plasma concentration(Tmax; hrs) for Forms I and V were calculated from [plasma] vs time profiles.

1 secondary outcome

Number of Study Participants Who Tolerated a Single Dose of ST-246 Form I vs. Form V as Determined by No Clinically Significant Changes in Safety Parameters
Time frame: 4 weeks

Results and safety

Results posted to the registry on 9 Feb 2010, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
ST-246 Form I Followed by Form V	6	6
ST-246 Form V Followed by Form I	6	6

Primary outcome: Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: t½

Time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs. Mean (Standard Deviation). Unit: hours

Measure	ST-246 Form I n = 11	ST-246 Form V n = 8
Value	27.446 (13.109)	28.180 (21.992)

ST-246 Form I vs ST-246 Form V: p = 0.4591, ANOVA

Population analysed: Both groups started with 12 particpants. Outlier values were excluded from the half-life analyses for 3 subject PK profiles (one Form I and 2 Form V). Form V group lost a particpant during wash-out period due to death in the family.

Primary outcome: Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: AUC0-τ

Time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs. Mean (Standard Deviation). Unit: ng*hr/mL

Measure	ST-246 Form I n = 12	ST-246 Form V n = 11
Value	15624.495 (5449.188)	20065.316 (6744.974)

ST-246 Form I vs ST-246 Form V: p = 0.0048, ANOVA

Population analysed: Both groups started with 12 particpants. Form V group lost a particpant during wash-out period due to death in the family.

Primary outcome: Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: AUC0-∞

Time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs. Mean (Standard Deviation). Unit: ng*hr/mL

Measure	ST-246 Form I n = 11	ST-246 Form V n = 8
Value	19922.017 (6543.563)	21982.709 (9330.953)

ST-246 Form I vs ST-246 Form V: p = 0.0997, ANOVA

Population analysed: Both groups started with 12 particpants. Outlier values were excluded from analyses for 3 subject PK profiles (one Form I and 2 Form V). Form V group lost a particpant during wash-out period due to death in the family.

Primary outcome: Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: Cmax

Time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs. Mean (Standard Deviation). Unit: ng/mL

Measure	ST-246 Form I n = 12	ST-246 Form V n = 11
Value	1068.9 (294.3)	1230.2 (348.6)

ST-246 Form I vs ST-246 Form V: p = 0.0422, ANOVA

Population analysed: Both groups started with 12 particpants as 'per protocol'. Form V group lost a particpant during wash-out period due to death in the family.

1 secondary outcome is reported in the full results.

Adverse events

Time frame: 4 weeks. Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
ST-246 Form I	0 of 12 (0%)	1 of 12 (8.3%)	Not reported
ST-246 Form V	0 of 11 (0%)	2 of 11 (18.2%)	Not reported

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 1 Oct 2026.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Derived from this study: PubMed 36263798Hatmal MM, Al-Hatamleh MAI, Olaimat AN, Ahmad S, Hasan H, Ahmad Suhaimi NA, Albakri KA, Abedalbaset Alzyoud A, Kadir R, Mohamud R. Comprehensive literature review of monkeypox. Emerg Microbes Infect. 2022 Dec;11(1):2600-2631. doi: 10.1080/22221751.2022.2132882.

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.

Thomas C Marbury, MD principal investigator

Orlando Clinical Research Center

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

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing ST-246 Days 1 - 3 and ST-246 Days 11 - 13 in people with Orthopoxviral Disease and Smallpox, run by SIGA Technologies at 1 site 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 12 inclusion and 36 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 1 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site 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 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

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 9 Feb 2010). 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?

Pharmacokinetic Parameters for a Single Dose of ST-246 Form I vs. Form V: t½ (time frame: Post-dose samples at 0.5,1,2,3,4,8,12,24,36,48,72 hrs). The study lists 5 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 NCT00728689, 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 1 Oct 2026; AzTrials last refreshed its copy on 26 Oct 2026.