Related Experiment Video
Updated: Aug 14, 2026
A Neonatal Imaging Model of Gram-Negative Bacterial Sepsis
Published on: August 12, 2020
Clinical evaluation of mezlocillin in neonates
Insights
Mezlocillin is effective for treating gram-negative bacterial infections in neonates. Recommended dosing is 75 mg/kg every 12 hours, showing good clinical outcomes and minimal side effects.
Area of Science:
- Pharmacology
- Neonatal Medicine
- Infectious Diseases
Background:
- Gram-negative bacterial infections pose a significant threat to neonates.
- Ureidopenicillins, like mezlocillin, are used to combat these infections.
- Understanding mezlocillin pharmacokinetics and efficacy in neonates is crucial for optimal treatment.
Purpose of the Study:
- To evaluate the pharmacokinetics of single-dose mezlocillin in neonates.
- To assess the efficacy and safety of mezlocillin in treating neonatal gram-negative bacterial infections.
- To determine appropriate dosing regimens for mezlocillin in this population.
Main Methods:
- Single-dose pharmacokinetic studies in 64 infants (0-6 days old) receiving intravenous or intramuscular mezlocillin (75 mg/kg).
- Treatment efficacy and safety evaluation in 165 neonates with suspected sepsis, including microbiological and clinical assessments.
- Analysis of cerebrospinal fluid penetration after multiple doses.
Main Results:
- Mean serum concentrations at 1 hour were 107 µg/ml (≤1 day old) and 82.5 µg/ml (>6 days old).
- Serum clearance ranged from 3.0 to 6.4 hours.
- 24 out of 27 evaluable neonates achieved clinical and bacteriological cure; cerebrospinal fluid penetration was 18-45% of serum levels. Three gram-negative strains showed in vitro resistance.
Conclusions:
- Mezlocillin is an effective ureidopenicillin for neonatal gram-negative bacterial infections.
- A recommended dosing regimen is 75 mg/kg every 12 hours via IV infusion or IM injection.
- The drug demonstrated a favorable safety profile with no significant adverse effects observed.
Abstract:
Single-dose pharmacokinetic studies were performed in 64 infants, ranging in age from less than 1 day to 6 days, after intravenous infusion or intramuscular injection of approximately 75 mg/kg of mezlocillin. Mean serum concentrations at one hour were 107 micrograms/ml and 82.5 micrograms/ml for neonates less than or equal to 1 day of age and greater than or equal to 6 days of age, respectively. The serum clearance ranged from 3.0 to 6.4 hours. Based on data from the study, it is recommended that mezlocillin be administered to neonates with gram-negative bacterial infections in a single dose of 75 mg/kg, either as an intravenous infusion over 30 minutes or as an intramuscular injection, every 12 hours during the first week of life. Mezlocillin alone or in conjunction with penicillin was used in treating 165 neonates with suspected sepsis. Gram-negative organisms were recovered from 18 of the 27 neonates from whom pathogens were isolated. Three of these 18 strains, a Klebsiella oxytoca, an Acinetobacter anitratum, and a Haemophilus influenzae, were resistant to mezlocillin in vitro. Twenty-four of the 27 patients who satisfied criteria for evaluation achieved a bacteriological and a clinical cure. Cerebrospinal fluid permeation after multiple doses ranged from 18% to 45% of serum levels. No significant local or systemic side effects were seen. The results indicate that mezlocillin is an effective ureidopenicillin for the treatment of gram-negative bacterial infections.
