Characterization of the Preclinical in Vitro and in Vivo Pharmacokinetic Properties of the Cyclic Oligomeric Depsipeptide Ryanodine Receptor 2 Inhibitor ent-Verticilide
- 1Vanderbilt University Medical Center
Abstract
ent-Verticilide is a synthetic cyclic oligomeric depsipeptide that inhibits ryanodine receptor 2 (RyR2)-mediated calcium (Ca) leak and has demonstrated antiarrhythmic activity in mice. This study characterized the preclinical absorption, distribution, metabolism, and pharmacokinetic properties of ent-verticilide and investigated factors affecting its oral exposure. ent-Verticilide was stable in rat plasma and simulated gastric and intestinal fluids but exhibited extensive plasma protein binding (>94%) and low apparent permeability in Caco-2 cells, with no evidence of pronounced net efflux. In rat and human liver microsomes, ent-verticilide underwent rapid NADPH-dependent metabolism, with an in vitro half-life of 5.43 min and 4.35 min, respectively, and a predicted hepatic extraction ratio of 0.90 and 0.92, respectively. Following intravenous administration in rats, ent-verticilide exhibited a systemic clearance of 25.5 mL/min/kg and a large steady-state volume of distribution (4.72 L/kg). Absolute oral bioavailability was approximately 16%. Simultaneous portal and systemic sampling estimated intestinal availability (FaFg) at 0.25 and hepatic availability (Fh) at 0.64, suggesting that processes occurring before hepatic entry are a major limitation to oral exposure. Pretreatment with the CYP inhibitor 1-aminobenzotriazole increased portal and systemic exposure approximately 10.6- and 18.5-fold, respectively, and increased apparent Fh to approximately 1. Collectively, these findings identify limited intestinal availability and CYP-mediated presystemic metabolism as important determinants of ent-verticilide exposure and provide a framework for its continued development as an RyR2-targeted therapeutic.
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BibTeX
@misc{do2026characterization,
title = {{Characterization of the Preclinical in Vitro and in Vivo Pharmacokinetic Properties of the Cyclic Oligomeric Depsipeptide Ryanodine Receptor 2 Inhibitor ent-Verticilide}},
author = {T. Q. Do and R. D. Crouch and K. Wu and M. P. Thorpe and A. N. Smith and J. N. Johnston and W. S. Akers and B. C. Knollmann},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.26.761690},
url = {https://www.biorxiv.org/content/10.64898/2026.10.26.761690v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Characterization of the Preclinical in Vitro and in Vivo Pharmacokinetic Properties of the Cyclic Oligomeric Depsipeptide Ryanodine Receptor 2 Inhibitor ent-Verticilide
AU - T. Q. Do
AU - R. D. Crouch
AU - K. Wu
AU - M. P. Thorpe
AU - A. N. Smith
AU - J. N. Johnston
AU - W. S. Akers
AU - B. C. Knollmann
PY - 2026
DA - 2026/10/26
PB - bioRxiv
DO - 10.64898/2026.10.26.761690
UR - https://www.biorxiv.org/content/10.64898/2026.10.26.761690v1
AB - ent-Verticilide is a synthetic cyclic oligomeric depsipeptide that inhibits ryanodine receptor 2 (RyR2)-mediated calcium (Ca) leak and has demonstrated antiarrhythmic activity in mice. This study characterized the preclinical absorption, distribution, metabolism, and pharmacokinetic properties of ent-verticilide and investigated factors affecting its oral exposure. ent-Verticilide was stable in rat plasma and simulated gastric and intestinal fluids but exhibited extensive plasma protein binding (>94%) and low apparent permeability in Caco-2 cells, with no evidence of pronounced net efflux. In rat and human liver microsomes, ent-verticilide underwent rapid NADPH-dependent metabolism, with an in vitro half-life of 5.43 min and 4.35 min, respectively, and a predicted hepatic extraction ratio of 0.90 and 0.92, respectively. Following intravenous administration in rats, ent-verticilide exhibited a systemic clearance of 25.5 mL/min/kg and a large steady-state volume of distribution (4.72 L/kg). Absolute oral bioavailability was approximately 16%. Simultaneous portal and systemic sampling estimated intestinal availability (FaFg) at 0.25 and hepatic availability (Fh) at 0.64, suggesting that processes occurring before hepatic entry are a major limitation to oral exposure. Pretreatment with the CYP inhibitor 1-aminobenzotriazole increased portal and systemic exposure approximately 10.6- and 18.5-fold, respectively, and increased apparent Fh to approximately 1. Collectively, these findings identify limited intestinal availability and CYP-mediated presystemic metabolism as important determinants of ent-verticilide exposure and provide a framework for its continued development as an RyR2-targeted therapeutic.
ER -