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Enhanced Brain Delivery of 2-(Phosphonomethyl)pentanedioic Acid Following Intranasal Administration of Its ?-Substituted Ester Prodrugs.

ABSTRACT: 2-(Phosphonomethyl)pentanedioic acid (2-PMPA) is a potent and selective inhibitor of glutamate carboxypeptidase-II (GCPII) with efficacy in multiple neurological and psychiatric disease models, but its clinical utility is hampered by low brain penetration due to the inclusion of multiple acidic functionalities. We recently reported an improvement in the brain-to-plasma ratio of 2-PMPA after intranasal (IN) dosing in both rodents and primates. Herein, we describe the synthesis of several 2-PMPA prodrugs with further improved brain delivery of 2-PMPA after IN administration by masking of the ?-carboxylate. When compared to IN 2-PMPA in rats at 1 h post dose, ?-(4-acetoxybenzyl)-2-PMPA (compound 1) resulted in significantly higher 2-PMPA delivery to both plasma (4.1-fold) and brain (11-fold). Subsequent time-dependent evaluation of 1 also showed high brain as well as plasma 2-PMPA exposures with brain-to-plasma ratios of 2.2, 0.48, and 0.26 for olfactory bulb, cortex, and cerebellum, respectively, as well as an improved sciatic nerve to plasma ratio of 0.84. In contrast, IV administration of compound 1 resulted in similar plasma exposure of 2-PMPA versus the IN route (AUCIV: 76 ± 9 h·nmol/mL versus AUCIN: 99 ± 24 h·nmol/mL); but significantly lower nerve and brain tissue exposures with tissue-to-plasma ratios of 0.21, 0.03, 0.04, and 0.04 in nerve, olfactory bulb, cortex, and cerebellum, respectively. In primates, IN administration of 1 more than doubled 2-PMPA concentrations in the cerebrospinal fluid relative to previously reported levels following IN 2-PMPA. The results of these experiments provide a promising strategy for testing GCPII inhibition in neurological and psychiatric disorders.

SUBMITTER: Nedelcovych M

PROVIDER: S-EPMC5795618 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Enhanced Brain Delivery of 2-(Phosphonomethyl)pentanedioic Acid Following Intranasal Administration of Its γ-Substituted Ester Prodrugs.

Nedelcovych Michael M Dash Ranjeet P RP Tenora Lukáš L Zimmermann Sarah C SC Gadiano Alexandra J AJ Garrett Caroline C Alt Jesse J Hollinger Kristen R KR Pommier Elie E Jančařík Andrej A Rojas Camilo C Thomas Ajit G AG Wu Ying Y Wozniak Krystyna K Majer Pavel P Slusher Barbara S BS Rais Rana R

Molecular pharmaceutics 20170831 10

2-(Phosphonomethyl)pentanedioic acid (2-PMPA) is a potent and selective inhibitor of glutamate carboxypeptidase-II (GCPII) with efficacy in multiple neurological and psychiatric disease models, but its clinical utility is hampered by low brain penetration due to the inclusion of multiple acidic functionalities. We recently reported an improvement in the brain-to-plasma ratio of 2-PMPA after intranasal (IN) dosing in both rodents and primates. Herein, we describe the synthesis of several 2-PMPA p ...[more]

PMID: 28763226

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Project description:We previously reported that intranasal insulin protects substantia nigra dopaminergic neurons against 6-hydroxydopamine neurotoxicity in rats. This study aimed to assess insulin pharmacokinetics in the rat brain following intranasal application. Recombinant human insulin (rh-Ins) or phosphate buffer solution was administered to both nostrils of rats. Animals were sacrificed at 15 minutes, 1, 2, and 6 hours to determine insulin levels in different brain regions by an ultrasensitive, human-specific enzyme-linked immunosorbent assay kit. For fluorescence tracing study, rats were administered with intranasal florescence-tagged insulin (Alex546-Ins), and brains were fixed at 10 and 30 minutes to prepare sagittal sections. rh-Ins was detected in all brain regions examined except the cerebral cortex. The highest levels were detected in the brainstem, followed by the cerebellum, substantia nigra/ventral tegmental area, olfactory bulb, striatum, hippocampus, and thalamus/hypothalamus. Insulin levels reached a peak at 15 minutes and then declined gradually overtime, but remained significantly higher than baseline levels at 6 hours in most regions. Consistently, widespread Alex546-Ins-binding cells were detected in the brain at 10 and 30 minutes, with the olfactory bulb and brainstem showing the highest while the cerebral cortex showing lowest fluorescence signals. Double-immunostaining showed that Alex546-Ins-bindings were primarily co-localized with neuronal nuclei-positive neurons. In the subtantia nigra, phospho-Akt was found to be activated in a subset of Alex546-Ins and tyrosine hydroxylase double-labeled cells, suggesting activation of the Akt/PI3K pathway in these dopaminergic neurons. Data from this study suggest that intranasal insulin could effectively reach deep brain structures including the nigrostriatal pathways, where it binds to dopaminergic neurons and activates intracellular cell survival signaling. This study was approved by the Institutional Animal Care Committee at the University of Mississippi Medical Center (protocol 1333A) on June 29, 2015.

Dataset Information

Enhanced Brain Delivery of 2-(Phosphonomethyl)pentanedioic Acid Following Intranasal Administration of Its ?-Substituted Ester Prodrugs.

Publications

Enhanced Brain Delivery of 2-(Phosphonomethyl)pentanedioic Acid Following Intranasal Administration of Its γ-Substituted Ester Prodrugs.

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