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

center dot Albendazole is used in several anthelminthic drug programs. center dot It may be necessary to include sectors of the community (such as breastfeeding women) not previously involved in community or clinical programmes (e.g. filariasis, hydatid disease) to achieve a reasonable level of elimination of the worm. center dot However, there are no studies in which the amount of the drug and/or its metabolites in the milk of lactating women was analysed, so as to assess the possible exposure of the breastfed infant. WHAT THIS STUDY ADDS center dot In the present study, the concentrations of albendazole and its active metabolite (albendazole sulphoxide) were analysed in the milk of lactating women through 36 h after administration of a single (400 mg) oral dose of albendazole. center dot Albendazole was barely secreted in milk as such. center dot On the other hand, albendazole sulphoxide was analysed through the 36 h of the study, and it was concluded that albendazole and albendazole sulphoxide attain levels in breast milk that are unlikely to be considered harmful for the breastfed infant. center dot These findings would help in deciding whether to involve breastfeeding mothers in albendazole mass drug administration programmes. 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 C-max, T-max, t(1/2) and AUC(0-36), 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.