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The Mesenteric Lymph Duct Cannulated Rat Model: Application to the Assessment of Intestinal Lymphatic Drug Transport

The intestinal lymphatic system plays key roles in fluid transport, lipid absorption and immune function. Lymph flows directly from the small intestine ...

Monash University (Parkville Campus)

The purpose of this work was to investigate the potential of poly(ε-caprolactone)-block-poly(ethyl ethylene phosphate) (PCL-PEEP) micelles for brain-targeting drug delivery.

Poly(ε-caprolactone)-block-poly(ethyl ethylene phosphate) micelles for brain-targeting drug delivery: in vitro and in vivo valuation.

Micelle-based brain-targeted drug delivery enabled by a nicotine acetylcholine receptor ligand.

The successful treatment of central nervous system (CNS) disorders is hampered by inefficient drug delivery across the blood-brain barrier (BBB). Transferrin (Tf) could facilitate the transcytosis of coupled nanocarriers through Tf receptor (TfR) mediated pathway. In this study, Tf-modified paclitaxel-loaded polyphosphoester hybrid micells (TPM) was prepared and evaluated for its in vitro and in vivo brain-targeting efficiency. The polyphosphoester hybrid micelle formed a core-shell structure in aqueous solution, and demonstrated high drug entrapping efficiency (89.9±3.4%). In addition, the micelle showed negligible hemolysis even at 2.0 mg/mL. The TPM was 87.85±2.32 nm with ζ potentials -12.33±1.46 mV, and PTX showed sustained release from TPM. TPM demonstrated enhanced cellular uptake and brain accumulation, which were 2 and 1.8-fold of PM, respectively. TPM exhibited strongest anti-glioma activity, and the mean survival time of mice bearing intracranial U-87 MG glioma treated with TPM (39.5 days) was significantly longer than those treated with Taxol® (33.6 days). These results indicated that Tf conjugated micelle could be a promising carrier for brain-targeting drug delivery.

Transferrin-conjugated polyphosphoester hybrid micelle loading paclitaxel for brain-targeting delivery: synthesis, preparation and in vivo evaluation.

The effective chemotherapy for glioblastoma multiform (GBM) requires a nanomedicine that can both penetrate the blood-brain barrier (BBB) and target the glioma cells subsequently. In this study, Transferrin (Tf) modified cyclo-[Arg-Gly-Asp-d-Phe-Lys] (c[RGDfK])-paclitaxel conjugate (RP) loaded micelle (TRPM) was prepared and evaluated for its targeting efficiency, antiglioma activity, and toxicity in vitro and in vivo. Tf modification significantly enhanced the cellular uptake of TRPM by primary brain microvascular endothelial cells (BMEC) to 2.4-fold of RP loaded micelle (RPM) through Tf receptor mediated endocytosis, resulting in a high drug accumulation in the brain after intravenous injection.The c[RGDfK] modified paclitaxel (PTX) was released from micelle subsequently and targeted to integrin overexpressed glioma cells in vitro, and showed significantly prolonged retention in glioma tumor and peritumoral tissue. Most importantly, TRPM exhibited the strongest antiglioma activity, as the mean survival time of mice bearing intracranial U-87 MG glioma treated with TRPM (42.8 days) was significantly longer than those treated with Tf modified PTX loaded micelle (TPM) (39.5 days), PTX loaded micelle (PM) (34.8 days), Taxol (33.6 days), and saline (34.5 days). Noteworthy, TRPM did not lead to body weight loss compared with saline and was less toxic than TPM. These results indicated that TRPM could be a promising nanomedicine for glioma chemotherapy.

Transferrin-modified c[RGDfK]-paclitaxel loaded hybrid micelle for sequential blood-brain barrier penetration and glioma targeting therapy.

This work investigates the influence of drug absorption route (intestinal lymphatics vs. blood supply) on drug pharmacokinetics and tissue distribution. To achieve this aim, the pharmacokinetics and tissue distribution of model compounds [1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane, DDT; halofantrine] and lipids were assessed following intravenous delivery in lymph lipoproteins or plasma, and were found to differ significantly. For DDT, the clearance (CL) and volume of distribution (Vd ) were higher, whereas for halofantrine, CL and V(d) were lower, after entry in lymph versus plasma due, in particular, to differences in adipose tissue and liver uptake. In a recent study, halofantrine CL and V(d) were similar following entry in lymph or entry in plasma into the systemic circulation of animals predosed with lymph, whereas in the current study, predosing lymph did not influence DDT CL and V(d). For compounds such as DDT, changes to the route of absorption may thus directly impact on pharmacokinetics and tissue distribution, whereas for halofantrine factors that influence lymphatic transport may, by altering systemic lipoprotein concentrations, indirectly impact pharmacokinetics and tissue distribution. Ultimately, careful control of dosing conditions (formulation, prandial state), and thus the extent of lymphatic transport, may be important in assuring reproducible efficacy and toxicity for lymphatically transported drugs.

The impact of lymphatic transport on the systemic disposition of lipophilic drugs.

A lipophilic prodrug approach has been used to promote the delivery of a model immunomodulator, mycophenolic acid (MPA), to the lymphatic system after oral administration. Lymphatic transport was employed to facilitate enhanced drug uptake into lymphocytes, as recent studies demonstrate that targeted drug delivery to lymph resident lymphocytes may enhance immunomodulatory effects. Two classes of lymph-directing prodrugs were synthesised. Alkyl chain derivatives (octyl mycophenolate, MPA-C8E; octadecyl mycophenolate, MPA-C18E; and octadecyl mycophenolamide, MPA-C18AM), to promote passive partitioning into lipids in lymphatic transport pathways, and a triglyceride mimetic prodrug (1,3-dipalmitoyl-2-mycophenoloyl glycerol, 2-MPA-TG) to facilitate metabolic integration into triglyceride deacylation-reacylation pathways. Lymphatic transport, lymphocyte uptake and plasma pharmacokinetics were assessed in mesenteric lymph and carotid artery cannulated rats following intraduodenal infusion of lipid-based formulations containing MPA or MPA prodrugs. Patterns of prodrug hydrolysis in rat digestive fluid, and cellular re-esterification in vivo, were evaluated to examine the mechanisms responsible for lymphatic transport. Poor enzyme stability and low absorption appeared to limit lymphatic transport of the alkyl derivatives, although two of the three alkyl chain prodrugs - MPA-C18AM (6-fold) and MPA-C18E (13-fold) still increased lymphatic drug transport when compared to MPA. In contrast, 2-MPA-TG markedly increased lymphatic drug transport (80-fold) and drug concentrations in lymphocytes (103-fold), and this was achieved via biochemical incorporation into triglyceride deacylation-reacylation pathways. The prodrug was hydrolysed rapidly to 2-mycophenoloyl glycerol (2-MPA-MG) in the presence of rat digestive fluid, and 2-MPA-MG was subsequently re-esterified in the enterocyte with oleic acid (most likely originating from the co-administered formulation) prior to accessing the lymphatics and lymphocytes. Importantly, after administration of 2-MPA-TG, the concentrations of free MPA in the mesenteric lymph nodes were significantly enhanced (up to 28 fold) when compared to animals administered equimolar quantities of MPA, suggesting the efficient conversion of the esterified prodrug back to the pharmacologically active parent drug. The data suggest that triglyceride mimetic prodrugs have potential as a means of enhancing immunotherapy via drug targeting to lymphocytes and lymph nodes.

Targeted delivery of a model immunomodulator to the lymphatic system: comparison of alkyl ester versus triglyceride mimetic lipid prodrug strategies.

Recent studies have demonstrated the potential for a triglyceride (TG) mimetic prodrug to promote the delivery of mycophenolic acid (MPA) to the lymphatic system. Here, the metabolic pathways that facilitate the lymphatic transport of the TG prodrug (1,3-dipalmitoyl-2-mycophenoloyl glycerol, 2-MPA-TG) were examined to better inform the design of next generation prodrugs.

Luojuan Hu

Drug Delivery,
Disposition,
and Dynamics,
Monash Institute of Pharmaceutical Sciences,
Drug Delivery, Disposition, and Dynamics, Monash Institute of Pharmaceutical Sciences

Monash University (Parkville Campus)

The Mesenteric Lymph Duct Cannulated Rat Model: Application to the Assessment of Intestinal Lymphatic Drug Transport

Luojuan Hu

Drug Delivery,Disposition,and Dynamics,Monash Institute of Pharmaceutical Sciences,Drug Delivery, Disposition, and Dynamics, Monash Institute of Pharmaceutical Sciences

Monash University (Parkville Campus)

The Mesenteric Lymph Duct Cannulated Rat Model: Application to the Assessment of Intestinal Lymphatic Drug Transport

Drug Delivery,
Disposition,
and Dynamics,
Monash Institute of Pharmaceutical Sciences,
Drug Delivery, Disposition, and Dynamics, Monash Institute of Pharmaceutical Sciences