Tissue time course and bioavailability of the pyrethroid insecticide bifenthrin in the Long-Evans rat

• Published in: Xenobiotica 2016-05, Vol.46 (5), p.430-438
• Main Authors: Hughes, Michael F., Ross, David G., Edwards, Brenda C., DeVito, Michael J., Starr, James M.
• Format: Article
• Language: English
• Subjects: Adipose Tissue - drug effects; Administration, Intravenous; Administration, Oral; Animals; Bifenthrin; Blood - drug effects; Brain - drug effects; Chromatography, High Pressure Liquid; disposition; Insecticides - administration & dosage; Insecticides - pharmacokinetics; Liver - drug effects; Male; pharmacokinetics; Pyrethrins - administration & dosage; Pyrethrins - pharmacokinetics; pyrethroids; Rats; Rats, Long-Evans; Risk Assessment; Tandem Mass Spectrometry; Time Factors; Tissue Distribution
• ISSN: 0049-8254; 1366-5928
• DOI: 10.3109/00498254.2015.1081710

1. Pyrethroids are neurotoxic and parent pyrethroid appears to be toxic entity. This study evaluated the oral disposition and bioavailability of bifenthrin in the adult male Long-Evans rat. 2. In the disposition study, rats were administered bifenthrin (0.3 or 3 mg/kg) by oral gavage and serially sacrificed (0.25 h to 21 days). Blood, liver, brain and adipose tissue were removed. In the bioavailability study, blood was collected serially from jugular vein cannulated rats (0.25 to 24 h) following oral (0.3 or 3 mg/kg) or intravenous (0.3 mg/kg) administration of bifenthrin. Tissues were extracted and analyzed for bifenthrin by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). 3. Bifenthrin concentration in blood and liver peaked 1-2-h postoral administration and were approximately 90 ng/ml (or g) and 1000 ng/ml (or g) for both tissues at 0.3 and 3 mg/kg, respectively. Bifenthrin was rapidly cleared from both blood and liver. Brain concentrations peaked at 4-6 h and were lower than in blood at both doses (12 and 143 ng/g). Bifenthrin in adipose tissue peaked at the collected time points of 8 (157 ng/g) and 24 (1145 ng/g) h for the 0.3 and 3 mg/kg doses, respectively and was retained 21 days postoral administration. Following intravenous administration, the blood bifenthrin concentration decreased bi-exponentially, with a distribution half-life of 0.2 h and an elimination half-life of 8 h. Bifenthrin bioavailability was approximately 30%. These disposition and kinetic bifenthrin data may decrease uncertainties in the risk assessment for this pyrethroid insecticide.