Pharmacokinetic study of 3H-labelled PAF-acether II. Comparison with 3H-labelled lyso-PAF-acether after intravenous administration in the rabbit and protein binding.

The blood and plasma kinetics of intravenously administered 3H-labelled PAF-acether were determined in seven rabbits. PAF-acether was rapidly distributed and slowly eliminated. Individual variations were very small. The main route of metabolism involves deacetylation of the PAF-acether into lyso-PAF-acether, leading to an equilibrium between the two molecules (10%/90%). This equilibrium, observed within 30 minutes, was still the same after 6 hours suggesting in vivo reacetylation of lyso-PAF-acether into PAF-acether. However, this could not be verified. After intravenous administration of lyso-PAF-acether in two rabbits, PAF-acether could not be found in any blood sample. The pharmacokinetic behaviour of both PAF-acether and lyso-PAF-acether can be described by a three-compartment model.