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An Assessment of the Permeation Enhancer, 1-phenyl-piperazine (PPZ), on Paracellular Flux Across Rat Intestinal Mucosae in Ussing Chambers

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1-phenyl piperazine (PPZ) emerged from a Caco-2 monolayer screen as having high enhancement potential due to a capacity to increase permeation without significant toxicity. Our aim was to further explore the efficacy and toxicity of PPZ in rat ileal and colonic mucosae in order to assess its true translation potential.


Intestinal mucosae were mounted in Ussing chambers and apparent permeability coefficient (Papp) values of [14C]-mannitol and FITC-dextran 4 kDa (FD-4) and transepithelial electrical resistance (TEER) values were obtained following apical addition of PPZ (0.6–60 mM). Exposed issues were assessed for toxicity by histopathology and lactate dehydrogenase (LDH) release. Mucosal recovery after exposure was also assessed using TEER readings.


PPZ reversibly increased the Papp of both agents across rat ileal and distal colonic mucosae in concentration–dependent fashion, accompanied by TEER reduction, with acceptable levels of tissue damage. The complex mechanism of tight junction opening was part mediated by myosin light chain kinase, stimulation of transepithelial electrogenic chloride secretion, and involved activation of 5-HT4 receptors.


PPZ is an efficacious and benign intestinal permeation enhancer in tissue mucosae. However, its active pharmacology suggest that potential for further development in an oral formulation for poorly permeable molecules will be difficult.

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C10 :

Sodium salt of capric acid


Cystic fibrosis transmembrane regulator


Diketofumaryl piperazine




Fluorescein isothiocyanate




Hank’s balanced salt solution




Short circuit current


Krebs-Henseleit solution


Lactate dehydrogenase




Myosin light chain kinase


3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium


Sodium/potassium/chloride cotransporter


Apparent permeability coefficient


Protein kinase A


Protein kinase C


1-phenyl piperazine


Transepithelial electrical resistance


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This study was co-funded by Science Foundation Ireland grant 07/SRC B1144. V.A. Bzik was recipient of a UCD Ad Astra Scholarship. An abstract of this study was presented at the CRS Annual Meeting; Copenhagen, Denmark (2009).

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Correspondence to D. J. Brayden.

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Bzik, V.A., Brayden, D.J. An Assessment of the Permeation Enhancer, 1-phenyl-piperazine (PPZ), on Paracellular Flux Across Rat Intestinal Mucosae in Ussing Chambers. Pharm Res 33, 2506–2516 (2016).

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