An Observational Study on the Pharmacokinetics of Levofloxacin in Lactating Atypical Pneumonia Patients.

Importance

Atypical pneumonia in postpartum women may alter drug pharmacokinetics (PK) through cytokine-mediated changes in vascular permeability, yet the breast milk disposition of levofloxacin in this population remains uncharacterized.

Objective

This observational study aimed to compare levofloxacin PK in lactating atypical pneumonia patients (n = 10) receiving 400 mg once daily for 3 days with historical healthy controls and to assess infant exposure risks.

Methods

Breast milk samples from subjects 6-10 were collected at predetermined time points (0.5, 1, 2, 4, 6, 8, 10, 12, and 24 hours) following the last dose of 3 days. Subjects 1-5 had random daytime sampling. The concentration of levofloxacin in breast milk was measured using a validated high-performance liquid chromatography method with ultraviolet detection (correlation coefficient: 0.9997; limit of detection: 0.15 μg/mL; recovery: 91.36-102.28%; RSD <5%). PK parameters were derived using noncompartmental analysis in Phoenix WinNonlin (version 8.35).

Results

Key milk PK parameters included Cmax of subjects 1-5 was 15.74 ± 6.55 μg/mL, and in subjects 6-10 was 14.55 ± 2.56 μg/mL. The elimination half-life (t1/2β) in subjects 1-5 was 7.46 ± 3.39 hours and in subjects 6-10 was 4.57 ± 1.14 hours. The AUC0-24 in subjects 1-5 was 84.31 ± 22.60 mg·h/L and in subjects 6-10 was 63.99 ± 11.78 mg·h/L.

Conclusions

Based on a 150 mL/kg/day milk intake, the estimated infant daily exposure in subjects 1-5 and 6-10 was 0.53 ± 0.14 and 0.40 ± 0.07 μg/kg/day, respectively, which was below 10% of the therapeutic dose (10 mg/kg once daily) for infants aged 0-12 months. This study first quantified levofloxacin in atypical pneumonia patients' breast milk using a validated method. Results suggest that breastfeeding can continue cautiously during maternal levofloxacin therapy. Avoid breastfeeding at peak drug concentration and monitor the infant for potential reactions.