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Linezolid pharmacokinetics in pediatric patients: an overview
Gail L Jungbluth1, Ian R Welshman, Nancy K Hopkins
1Clinical Pharmacology Unit, Pharmacia Corp., Kalamazoo, MI, USA
Insights
Pediatric linezolid dosing requires age-specific adjustments due to significant pharmacokinetic differences. Children under 12 need shorter dosing intervals for effective drug exposure against Gram-positive pathogens.
Area of Science:
- Pharmacology
- Pediatric Therapeutics
- Drug Metabolism
Background:
- Physiologic and developmental differences in children impact drug pharmacokinetics (absorption, distribution, metabolism, elimination).
- Establishing pediatric-specific pharmacokinetic data is crucial for developing safe and effective age-appropriate drug dosages.
- This review focuses on linezolid pharmacokinetics in pediatric patients and the basis for its approved dosing.
Purpose of the Study:
- To summarize linezolid's pharmacokinetic parameters in pediatric patients.
- To provide the rationale for current linezolid dosing recommendations in children.
- To highlight age-dependent variations in linezolid's drug exposure.
Main Methods:
- Evaluated linezolid pharmacokinetics in over 180 pediatric patients (preterm infants to 18 years) across 4 clinical trials.
- Administered single intravenous doses of linezolid to all study participants.
- Quantified plasma linezolid concentrations using validated high-performance liquid chromatography or liquid chromatography/mass spectrometry/mass spectrometry methods.
Main Results:
- Linezolid's elimination clearance is significantly age-dependent in pediatric populations.
- Children under 12 exhibit a smaller area under the curve, faster clearance, and shorter half-life compared to adults.
- Newborns show adult-like clearance, which rapidly increases within the first week of life, becoming 2-3 times higher than adults by day seven.
Conclusions:
- Higher clearance and lower area under the curve in children under 12 necessitate shorter linezolid dosing intervals.
- Age-specific dosing ensures adequate drug exposure to combat target Gram-positive pathogens in pediatric patients.
- Linezolid pharmacokinetics in children aged 12 and older are comparable to adult values, suggesting similar dosing may be appropriate.
Background:
There are a number of physiologic and developmental differences between children and adults that can influence the absorption, distribution, metabolism and elimination of a drug. Therefore it is important to determine the specific pharmacokinetic characteristics for individual drugs in pediatric patients so that appropriate age-specific dosage regimens can be developed and evaluated in clinical trials. This review summarizes the pharmacokinetic parameters of linezolid in pediatric patients and the rationale for the approved dosing recommendations for this population.
Methods:
The pharmacokinetics of linezolid in pediatric patients has been evaluated in 4 clinical trials, including >180 patients ranging in age from preterm newborn infants up to 18 years of age. In all of these studies, patients received a single intravenous dose of linezolid. Plasma linezolid concentrations have been determined by validated high performance liquid chromatography (adult studies) or liquid chromatography/mass spectrometry/mass spectrometry (pediatric studies) methods.
Results:
The pharmacokinetics of linezolid, especially elimination clearance, is age-dependent. Children younger than 12 years of age have a smaller area under the drug concentration-time curve, a faster clearance and a shorter elimination half-life than adults. Although clearance rates in newborn infants are similar to those in adults, clearance increases rapidly during the first week of life, becoming 2- to 3-fold higher than in adults by the seventh day of life. The clearance of linezolid decreases gradually among young children, becoming similar to adult values by adolescence. The pharmacokinetics of linezolid in children age 12 years and older is not significantly different from that of adults.
Conclusions:
Because of the higher clearance and lower area under the drug concentration-time curve, a shorter dosing interval for linezolid is required for children younger than 12 years of age to produce adequate drug exposure against target Gram-positive pathogens.