Linezolid Pharmacokinetics in Young InfantsPhase 4NCT07815613

Oral Antibiotic Pharmacokinetics in Young Infants

A Phase 4 study testing Linezolid (LZD) in people with Linezolid Pharmacokinetics in Young Infants and Pharmacokinetic Analysis, run by University of Colorado, Denver at 1 site in United States.

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts

Official record

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Trial summary

Who is it for?: Ages 0 to 90 days
Conditions the study is for: Linezolid Pharmacokinetics in Young Infants, Pharmacokinetic Analysis, Linezolid
What is being tested?: Linezolid (LZD)
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 40 participants
Where: 1 siteUnited States
Study dates: 1 Jan 2027to 31 Dec 2030
Phase: Phase 4

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 0 to 90 days
All sexes
No healthy volunteers
Child

Who may be able to join

Hospitalized neonate or young infant ≤90 days postnatal age at screening
Weight ≥2 kg
Receiving systemic antibiotic therapy
Tolerating enteral medication(s) and/or enteral feeds
Group 1: Receiving oral linezolid as part of routine clinical care.
Group 2: Receiving systemic antibiotic therapy but not prescribed linezolid clinically and eligible to receive a single oral study dose.

Who cannot join

Known hypersensitivity or allergy to linezolid
Renal dysfunction (defined by age-appropriate serum creatinine and/or urine output)
Hepatic dysfunction (AST or ALT ≥3x age-specific upper limit of normal or clinically significant hepatic failure)
Gastrointestinal disorders expected to significantly impair drug absorption (e.g., short bowel syndrome, severe malabsorption)
Severe anemia or other condition that precludes study-required blood sampling
Extracorporeal support or other devices expected to substantially alter drug pharmacokinetics (e.g., extracorporeal membrane oxygenation [ECMO]).
Therapeutic hypothermia
Ongoing clinical instability that, in the opinion of the treating team or principal investigator (PI), would make study participation unsafe (e.g., escalating vasoactive support or rapidly worsening organ dysfunction).

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

United States1 site

University of Colorado, Denver
Aurora, Colorado, 80045
Andrew S Haynes, MD, 720-777-6783, andrew.haynes@childrenscolorado.org
Andrew S Haynes, MD

Other trials in United States

About this study

Official title: Characterizing Absorption Kinetics of Oral Antibiotics in Young Infants to Enhance Precision Dosing

This observational study will characterize the pharmacokinetics of linezolid in young infants. Participants will receive linezolid either as part of routine clinical care or as a single, one-time study dose. Blood samples collected following linezolid administration will be used to measure drug concentrations and describe how linezolid is absorbed, distributed, metabolized, and eliminated in this population. Clinical information, including demographic characteristics, laboratory values, and treatment details, will also be collected. The results will be used to develop pharmacokinetic models to improve linezolid dosing recommendations and support precision dosing in young infants.

Read the detailed description

Young infants are at increased risk for serious bacterial infections, yet limited pharmacokinetic data are available to guide evidence-based dosing of oral linezolid in this population. Developmental changes in drug absorption, distribution, metabolism, and elimination during early infancy contribute to variability in drug exposure, making it difficult to optimize dosing using existing recommendations.

This prospective pharmacokinetic study will enroll young infants who receive linezolid either as part of routine clinical care or as a single, one-time study dose. Blood samples will be collected to measure plasma linezolid concentrations, and demographic, clinical, laboratory, and medication data will be collected from the medical record. These data will be used to develop pharmacokinetic models and evaluate sources of variability in linezolid exposure, including developmental and clinical factors.

The results of this study are expected to improve the understanding of oral linezolid pharmacokinetics in young infants and support the development of model-informed dosing strategies to optimize antibiotic exposure, maximize treatment effectiveness, and minimize toxicity in this vulnerable population.

Conditions: Linezolid Pharmacokinetics in Young Infants, Pharmacokinetic Analysis, Linezolid, Infant and Young Children
Being tested: Linezolid (LZD)
Keywords: linezolid, pharmacokinetics, neonate, infant, oral antibiotic

What participants receive

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

Linezolid (LZD)Drug
Linezolid is administered either as part of routine clinical care or as a single, one-time study dose (10 mg/kg/dose enterally), depending on study arm. Participants undergo pharmacokinetic blood sampling after linezolid administration to characterize drug disposition in young infants.

Study groups in NCT07815613
Study group	Role	What they receive
Group 1: Routine Clinical Linezolid	No intervention	Participants receiving linezolid as part of routine clinical care will undergo pharmacokinetic blood sampling and clinical data collection.
Group 2: Single Study Dose of Linezolid	Experimental	Participants will receive a single study-administered dose of linezolid (10 mg/kg/dose enterally) followed by pharmacokinetic blood sampling and clinical data collection. Receives: Drug: Linezolid (LZD)

What is being measured

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

Area under the plasma linezolid concentration versus time curve from 0 to 24 hours (AUC0-24)
Area under the plasma linezolid concentration versus time curve from 0 to 24 hours (AUC0-24) will be estimated using plasma linezolid concentrations collected after enteral administration of linezolid (either routine clinical dosing or a single study dose) and pharmacokinetic modeling. AUC0-24 will be reported in mcg hour per mL.
Measured: From 0 to 24 hours after administration of an enteral linezolid dose
Apparent clearance of linezolid (CL/F)
Apparent clearance of linezolid following enteral administration (either routine clinical dosing or a single study dose) will be estimated from plasma linezolid concentrations using population pharmacokinetic modeling. Apparent clearance will be reported in L/hour.
Measured: From 0 to 12 hours after administration an enteral linezolid dose
Apparent volume of distribution of linezolid (V/F)
Apparent volume of distribution of linezolid following enteral administration (either routine clinical dosing or a single study dose) will be estimated from plasma linezolid concentrations using population pharmacokinetic modeling. Apparent volume of distribution will be reported in L per kilogram of body weight.
Measured: From 0 to 12 hours after administration of an enteral linezolid dose
Absorption rate constant of linezolid (Ka)
The absorption rate constant of linezolid following enteral administration (either routine clinical dosing or a single study dose) will be estimated from plasma linezolid concentrations using population pharmacokinetic modeling. The absorption rate constant will be reported in 1/hour.
Measured: From 0 to 12 hours after administration of an enteral linezolid dose

Secondary outcomes (3)

Concentrations of Linezolid and Primary Metabolites in Plasma
Measure plasma concentrations of linezolid and its primary metabolites at prespecified sampling time points following routine clinical dosing or a single study dose.
Measured: From 0 to 12 hours after administration of an enteral linezolid dose
Percentage of participants achieving the prespecified linezolid pharmacodynamic target
Pharmacodynamic target attainment will be determined using model-estimated linezolid exposure and a prespecified pharmacodynamic target based on the AUC0-24/MIC ratio. The specific target threshold will be defined in the study analysis plan based on available pharmacodynamic data. The outcome will be reported as the percentage of participants achieving the prespecified target.
Measured: From 0 to 12 hours after administration of an enteral linezolid dose
Percentage of Participants Experiencing One or More Adverse Events or Serious Adverse Events
Adverse events and serious adverse events will be assessed from signing the informed consent form through study completion, up to 5 days. The incidence, severity, and type of adverse events and serious adverse events will be assessed. The outcome will be reported as the percentage of participants experiencing one or more adverse events or serious adverse events.
Measured: From signing the informed consent form through study completion, up to 5 days

Timeline

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

1 Jan 202731 Dec 2030

First posted11 Sep 2026
Study start1 Jan 2027 (estimated)
Primary completion31 Dec 2029 (estimated)
Study completion31 Dec 2030 (estimated)

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Other trials for Linezolid Pharmacokinetics in Young InfantsStudies of the same condition, open and under way.
More trials run by University of Colorado, DenverThe sponsor's other registered studies.
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 4
Primary purpose: Other
Allocation: Non-randomised
Intervention model: Parallel groups
Masking: None (open label)
Enrolment: 40 participants (estimated)

IDs, dates and publications

ClinicalTrials.gov ID: NCT07815613
Sponsor's protocol ID: 26-1733
Status last verified: Sep 2026
First submitted: 6 Aug 2026
Last updated: 11 Sep 2026
Results posted: No
Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: Undecided