Effect of dose on the biodistribution and pharmacokinetics of PLGA and PLGA-mPEG nanoparticles.

The effect of nanoparticle dose on the biodistribution and pharmacokinetics of conventional PLGA and stealth poly(Lactide-co-glycolide)-monomethoxypoly(ethyleneglycol) (PLGA-mPEG) nanoparticles was investigated. The precipitation-solvent diffusion method was used to prepare PLGA and PLGA-mPEG nanoparticles labeled with 125I-cholesterylaniline. These were administered intravenously (i.v.) in mice and at predetermined time intervals the animals were sacrificed and their tissues were excised and assayed for radioactivity. Within the dose range applied in this study, blood clearance and mononuclear phagocyte system (MPS) uptake of the PLGA nanoparticles depended on dose whereas they were independent of dose in the case of the PLGA-mPEG nanoparticles. Increasing the dose, decreased the rates of blood clearance and MPS uptake of the PLGA nanoparticles, indicating a certain degree of MPS saturation at higher doses of PLGA nanoparticles. The dose affected the distribution of PLGA nanoparticles between blood and MPS (liver) but it did not affect the nanoparticle levels in the other tissues. Within the range of doses applied here, the PLGA nanoparticles followed non-linear and dose-dependent pharmacokinetics whereas the PLGA-mPEG nanoparticles followed linear and dose-independent pharmacokinetics. In addition to the prolonged blood residence, the dosage-independence of the pharmacokinetics of the PLGA-mPEG nanoparticles would provide further advantages for their application in controlled drug delivery and in drug targeting.