P-glycoprotein (Pgp) overexpression in the blood brain barrier (BBB) is hypothesized to lower brain drug concentrations and thus inhibit anticonvulsant effects in drug-resistant epilepsy. Recently, the poly(butylcyanoacrylate) (PBCA) nanoparticle system was shown to overcome the obstacle of the BBB to deliver drugs into the brain. To determine whether pluronic P85-coated phenytoin poly(butylcyanoacrylate) nanoparticles (P85-PHT-PBCA-NPs) target PHT to the brain, PHT-resistant rats overexpressing Pgp in the BBB were screened by response to PHT treatment after chronic temporal lobe epilepsy induced by lithium-pilocarpine, followed by direct verification of PHT transport via measurement of brain PHT concentrations using microdialysis. Thereafter, the PHT-resistant rats were divided into three groups, which were treated with PHT, PHT + tariquidar (TQD), or P85-PHT-PBCA-NPs. PHT + TQD and P85-PHT-PBCA-NPs showed anticonvulsant activity in the PHT-resistant rats and increased the ratio of the area under the curve of the PHT concentrations in the brain/plasma in comparison with that observed in animals subjected to PHT treatment. However, the ratios of the PHT concentrations in the liver/plasma and kidney/plasma following P85-PHT-PBCA-NPs treatment were much lower than those measured following PHT + TQD treatment. Thus, Pgp overexpression decreases therapeutic drug concentrations in the brains of subjects with drug-resistant epilepsy and P85-PHT-PBCA-NPs could increase these drug concentrations.
Keywords: Drug resistance; Microdialysis; Nanoparticles; P-glycoprotein; Phenytoin; Tariquidar.
Copyright © 2016 Elsevier Ltd. All rights reserved.