PEPT1-mediated prodrug strategy for oral delivery of peramivir.

Peramivir was a novel and highly potent neuraminidase (NA) inhibitor for the treatment of influenza A and B. However, it exhibited a very low oral bioavailability (only 3%) due to the high polarity (log P of -1.4) and the low membrane permeability across the intestine. To utilize the PEPT1-mediated prodrug strategy to improve the oral absorption and develop the oral alternative, seven amino acid ester prodrugs and seven amino acid amide prodrugs have been synthesized. The permeability of these prodrugs across Caco-2 cells were screened. Peramivr-(CH2)2-l-Val and Peramivir-l-Ile were of the highest permeability in ester prodrugs and amide prodrugs, respectively, and then they were selected for further studies. Glycylsarcosine (gly-sar) uptake by Caco-2 could be inbihited by Peramivir-(CH2)2-l-Val and Peramivir-l-Ile in a concentration-dependent manner, and the IC50 was 1.34 ±â€¯0.31 mM and 1.78 ±â€¯0.48 mM, respectively. The direct uptake of Peramivir-(CH2)2-l-Val and Peramivir-l-Ile in MDCK-PEPT1 cells were significantly higher than in MDCK mock cells, and could be markedly inhibited by gly-sar. The uptake of Peramivir-(CH2)2-l-Val and Peramivir-l-Ile (0.01 to 50 mM) in MDCK-hPEPT1 cells conformed to Michaelis-Menten Equation. The oral bioavailability of peramivir was 65.3% and 37.3% after the oral administration of Peramivir-(CH2)2-l-Val and Peramivir-l-Ile to rats, respectively. The oral absorption and bioactivation of Peramivir-(CH2)2-l-Val was rapid and extensive, and no Peramivir-(CH2)2-l-Val was found in plasma. Because the amide bond was relatively stable, Peramivir-l-Ile could not be totally converted to the parent drug in vivo. Peramivir-(CH2)2-l-Val with good oral profiles and rapid bioactivation might be a promising prodrug for the further clinic development. The present study also corroborated the idea that the PEPT1-mediated prodrug approach has enormous promise for improving the oral absorption of poorly absorbed drug.

HPLC-MS/MS analysis of peramivir in rat plasma: Elimination of matrix effect using the phospholipid-removal solid-phase extraction method.

A simple HPLC-MS/MS method has been developed for the determination of peramivir in rat plasma in the present study. The analytes were separated on a C18 column (50 × 2.1 mm, 1.7 µm) and a triple-quadrupole mass spectrometer equipped with an electrospray ionization source was applied for the detection. A phospholipid-free cartridge solid-phase extraction was used to pretreat the plasma and eliminate the endogenous phospholipid. The in-source collision-induced dissociation approach showed that this pretreatment could result in negligible ion suppression from the extracted sample and could produce cleaner samples when compared with the protein precipitation. The method was linear over the concentration range of 0.12-1200.0 ng/mL for peramivir. The method was validated and successfully applied to a pharmacokinetic study after peramivir was orally and intravenously administered to Sprague-Dawley rats.

Simultaneous Determination and Pharmacokinetic Study of Six Components in Rat Plasma by HPLC-MS/MS after Oral Administration of Acanthopanax sessiliflorus Fruit Extract.

A specific and reliable HPLC-MS/MS method was developed and validated for the simultaneous determination of protocatechuic acid (PCA), scopolin, (-)-pinoresinol-4,4'-di-O-ß-d-glucopyranoside (PDG), acanthoside D, acanthoside B and hyperin in rat plasma for the first time. The analytes were separated on a C18 column (50 × 2.1 mm, 1.8 µm) and a triple-quadrupole mass spectrometer equipped with an electrospray ionization (ESI) source was used for detection. The rat plasma sample was prepared using the protein precipitation procedure. The calibration curves were linear over a concentration range of 1.2-1200.0 ng/mL for PCA, 0.96-960.0 ng/mL for scopolin, 1.12-1120.0 ng/mL for PDG, 1.32-1320.0 ng/mL for acanthoside D, 0.99-990.0 ng/mL for acanthoside B and 1.01-1010.0 ng/mL for hyperin. The intra-day and inter-day precision was less than 11.4% and the relative error (RE) was all within ±15%. The validated method was successfully applied to assess the pharmacokinetics characteristics after the extracts of Acanthopanax sessiliflorus fruits were orally administered to the Sprague-Dawley rat.