title: Determination of concentration of albendazole sulfoxide in plasma and uterine fluid of heifers.
abstract: OBJECTIVE
  To determine time and concentration of peak plasma and uterine fluid concentrations of albendazole (ABZ) sulfoxide (ABZSO) in heifers after oral administration of ABZ.
  
  
  METHODS
  25 young Angus and Simmental heifers maintained on pasture with ad libitum access to hay and water.
  
  
  METHODS
  Heifers were assigned at random to ABZ or control (water) groups, and were drenched with ABZ suspension at a dosage of 15, 30, 60, or 120 mg/kg of body weight, or with water. Plasma was collected hourly, from 14 to 25 hours after administration of ABZ or water. After a drug-withdrawal period, heifers were synchronized for estrus and drenched with 60 mg of ABZ/kg, or water (50 ml). Each uterine horn was flushed. All samples were extracted and subjected to high-performance liquid chromatography analysis.
  
  
  RESULTS
  For all groups, highest mean +/- SEM plasma concentration of ABZSO was observed between 15 and 16 hours after ABZ administration, at 2.0 +/- 0.4 micrograms/ml (15 mg/kg), 5.3 +/- 1.0 micrograms/ml (30 mg/kg), 7.4 +/- 1.5 micrograms/ml (60 mg/kg), and 11.1 +/- 2.7 micrograms/ml (120 mg/kg). Mean concentration for all uterine horn fluid samples was 265 +/- 25 ng/ml/horn; range was 79 to 546 ng/ml/horn. The only significant (P = 0.0006) source of variation was the technician performing the flush. Mean concentration for each technician was 184 +/- 24 ng/ml/horn and 345 +/- 35 ng/ml/horn.
  
  
  CONCLUSIONS
  Teratogenic and embryotoxic effects of ABZSO differ for ewes and heifers. Albendazole sulfoxide is detectable in the uterus of heifers; however, ABZSO peaks in heifer plasma earlier and at a lower concentration than that reported for ewes, perhaps contribution to differences in susceptibility at similar dosages.
authors.affiliation: Department of Animal Science, College of Veterinary Medicine, North Carolina State University, Raleigh 27606, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Piscopo
authors.forename: C E
authors.initials: CE
authors.lastname: Farin
authors.forename: S A
authors.initials: SA
authors.lastname: Bai
mesh_terms: D000284:Administration, Oral; D015766:Albendazole / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage / Q000032:analysis* / Q000097:blood*; D002417:Cattle / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods / Q000662:veterinary; D005260:Female; D011897:Random Allocation; D013997:Time Factors; D014599:Uterus / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000871:Anthelmintics; D015766:Albendazole; C027186:albendazole sulfoxide