Pharmacokinetics and pharmacodynamics of chlorpyrifos and 3,5,6-trichloro-2-pyridinol in rat saliva after chlorpyrifos administration

Details

• Personal Author:
  Klohe EM ; Lin Y ; Smith JN ; Timchalk C ; Wang J
• Description:
  Sensors have been developed for noninvasive biomonitoring of the organophosphate pesticide chlorpyrifos (CPF), and previous studies have suggested consistent partitioning of 3,5,6-trichloro-2-pyridinol (TCPy), a metabolite of CPF, into saliva after exposure to TCPy. The objective of this study was to quantitatively evaluate in vivo pharmacokinetics and pharmacodynamics of CPF and TCPy in saliva after CPF administration. Rats were coadministered CPF (0.5-5mg/kg) and pilocarpine (approximately 13 mg/kg) iv. Saliva and blood were collected, and levels of CPF, TCPy, and cholinesterase (ChE) activity were quantified. Experimental results suggest that CPF is rapidly metabolized after iv administration. Formation of TCPy from administered CPF at the low dose (0.5 mg/kg) was slower than from higher CPF doses, potentially due to differences in plasma protein binding to CPF. CPF was measured in saliva only at the first time point sampled (0-15 min), indicating low partitioning and rapid metabolism. After formation, TCPy pharmacokinetics were very similar in blood and saliva. Saliva/blood TCPy concentration ratios were not affected by TCPy concentration in blood, saliva flow rate, or salivary pH and were consistent with previous studies. ChE activity in plasma demonstrated a dose-dependent decrease, and ChE activity in saliva was extremely variable and demonstrated no dose relationship. A physiologically based pharmacokinetic and pharmacodynamic model for CPF was modified and predicted the data reasonably well. It is envisioned that a combination of biomonitoring compounds like TCPy in saliva coupled with computational modeling will form an approach to measure pesticide exposure to susceptible human populations such as agricultural workers. [Description provided by NIOSH]
• Subjects:
  Animals Biomarkers Blood Energy Metabolism Hematologic Tests Insecticides Laboratories Occupational Health Risk Assessment Risk Factors Safety

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• Keywords:
  3,5,6-trichloro-2-pyridinol Author Keywords: Chlorpyrifos Biomonitoring Blood-samples Exposure-levels Laboratory-animals Metabolism Models Pesticides Pharmacokinetics Protein-biochemistry Proteins Risk-factors Saliva TCPy Trichloropyridinol

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• ISSN:
  1096-6080
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 10 ; Washington
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  245-256
• Volume:
  130
• Issue:
  2
• NIOSHTIC Number:
  nn:20042672
• Citation:
  Toxicol Sci 2012 Dec; 130(2):245-256
• Contact Point Address:
  Jordan Ned Smith, Battelle Memorial Institute, Pacific Northwest Division, PO Box 999, Richland, WA 99352
• Email:
  jordan.smith@pnnl.gov
• CAS Registry Number:
  3,5,6-Trichloro-2-pyridinol (CAS RN 6515-38-4) ; Chlorpyrifos (CAS RN 2921-88-2)
• Federal Fiscal Year:
  2013
• NORA Priority Area:
  Agriculture, Forestry and Fishing
• Performing Organization:
  Battelle Pacific Northwest Laboratories
• Peer Reviewed:
  True
• Start Date:
  20060901
• Source Full Name:
  Toxicological Sciences
• End Date:
  20170831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:40007357f5c0fe1390cb732b9fb1f3272910596b8db93dacba37d06d8622b0f31a005199f82bc6e116a3e59bc735640782b96237fb703b782eb979cd28af8012
• Download URL:
  https://stacks.cdc.gov/view/cdc/194820/cdc_194820_DS1.pdf
• File Type:
  [PDF - 476.60 KB ]