Albendazole and its metabolites in the breast milk of lactating women following a single oral dose of albendazole

Aims: Albendazole (ABZ) is used in several anthelminthic drug programmws. ABZ side-effects are generally mild, but ABZ-induced pancytopenia may be serious. In filariasis programmes, it may be necessary to administer ABZ to breastfeeding women. Few data are available on safety of ABZ for breastfed infants. In addition, the pharmacokinetics of ABZ and its metabolites in human milk is insufficiently investigated. The aim was to study pharmacokinetics of ABZ and its metabolites [ABZ sulphoxide (ABSX) and ABZ sulphone] in the breast milk lactating women after one single oral dose of ABZ. Methods: Thirty-three lactating women (age 18-40 years) participated in the study. They received a single oral 400-mg dose of ABZ. Five milk samples were taken at 0, 6, 12, 24 and 36 h. One serum sample was taken after 6 h. Samples were analysed using high-performance liquid chromatography and pharmacokinetic analysis was performed. Results: ABZ was detectable in milk samples 6 h after the oral dose. The mean concentration of serum ABZ was 63.7 ± 11.9 ng ml-1. The pharmacokinetic parameters for ABSX were calculated as follows: 351.9 ± 32.4 ng ml-1, 6.9 ± 0.5 h, 12.4 ± 2.2 h and 5190.3 ± 482.8 ng*h ml-1 for Cmax, T max, t1/2 and AUC0-36, respectively. The milk-to-serum ratios (range) for ABZ and ABSX were 0.9 (0.2-6.5) and 0.6 (0.1-1.5), respectively. Conclusions: After an oral dose of 400 mg, ABZ and ABSX attain low concentrations in breast milk that are unlikely to be considered harmful for the breastfed infant.