Pharmacodynamic data on fosfomycin in underweight infants during the neonatal period

Area of Science:

• Pharmacokinetics
• Neonatal Medicine
• Infectious Diseases

Background:

• Underweight infants may exhibit altered drug metabolism and elimination due to physiological immaturity.
• Understanding fosfomycin pharmacokinetics is crucial for optimizing antimicrobial therapy in vulnerable neonatal populations.

Purpose of the Study:

• To investigate the blood levels, half-life, and elimination of fosfomycin in underweight infants at different developmental stages.
• To compare fosfomycin pharmacokinetics between early neonatal period (1-3 days) and later infancy (3-4 weeks).

Main Methods:

• A single intravenous dose of 50 mg/kg fosfomycin was administered to two groups of underweight infants.
• Blood samples were collected at 5 min, 1, 3, 6, 9, and 24 hours post-administration.
• Urine samples were collected over a 0-24 hour period. Antibiotic levels were quantified using microbiological diffusion assays.

Main Results:

• Fosfomycin elimination after 24 hours was significantly slower in infants aged 1-3 days compared to those aged 3-4 weeks.
• The mean half-life of fosfomycin was longer in the younger infant group (7 hours) than in the older infant group (4.9 hours).
• Lower quantities of fosfomycin were eliminated in the urine of the 1-3 day old infants within 24 hours.

Conclusions:

• Neonatal immaturity significantly influences fosfomycin elimination, leading to prolonged drug exposure in the first few days of life.
• The observed pharmacokinetic differences suggest a need for potential dose adjustments or extended dosing intervals for fosfomycin in very young or underweight infants.
• Further research is warranted to establish optimal fosfomycin dosing regimens for specific infant populations based on age and weight.