Oral Antibiotic Pharmacokinetics in Young Infants

NCT07815613 | Not Yet Recruiting Phase 4 FDA Drug

• 1 other identifier: 26-1733
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Linezolid Pharmacokinetics in Young Infants; Pharmacokinetic Analysis; Linezolid; Infant and Young Children

Keywords

linezolid; pharmacokinetics; neonate; infant; oral antibiotic

Outcome Measures

Primary Outcomes (4)

• 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.

  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.

  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.

  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.

  From 0 to 12 hours after administration of an enteral linezolid dose

Secondary Outcomes (3)

• Concentrations of Linezolid and Primary Metabolites in Plasma

  From 0 to 12 hours after administration of an enteral linezolid dose

• Percentage of participants achieving the prespecified linezolid pharmacodynamic target

  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

  From signing the informed consent form through study completion, up to 5 days

Other Outcomes (1)

• Difference between PBPK model predicted and observed linezolid plasma concentrations

  From 0 to 12 hours after administration of an enteral linezolid dose

Study Arms (2)

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.

Drug: Linezolid (LZD)

Interventions

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.

Group 2: Single Study Dose of Linezolid

Eligibility Criteria

• Age: 0 Days - 90 Days
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• 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.

You may not qualify if:

• 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).

Sponsors & Collaborators

• University of Colorado, Denver: lead

Study Sites (1)

University of Colorado, Denver

Aurora, Colorado, 80045, United States

Location

MeSH Terms

Interventions

Linezolid

Intervention Hierarchy (Ancestors)

Acetamides; Amides; Organic Chemicals; Acetates; Acids, Acyclic; Carboxylic Acids; Oxazolidinones; Oxazoles; Azoles; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 6, 2026
• First Posted: September 11, 2026
• Study Start (Estimated): January 1, 2027
• Primary Completion (Estimated): December 31, 2029
• Study Completion (Estimated): December 31, 2030
• Last Updated: September 11, 2026

Record last verified: 2026-09

Locations

US (1)