Rapid solid-phase extraction method to quantify [11C]-verapamil, and its [11C]-metabolites, in human and macaque plasma

Jashvant D. Unadkat, Francisco Chung, Lucy Sasongko, Dale Whittington, Sara Eyal, David Mankoff, Ann C. Collier, Mark Muzi, Jeanne Link

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Introduction: P-glycoprotein (P-gp), an efflux transporter, is a significant barrier to drug entry into the brain and the fetus. The positron emission tomography (PET) ligand, [11C]-verapamil, has been used to measure in vivo P-gp activity at various tissue-blood barriers of humans and animals. Since verapamil is extensively metabolized in vivo, it is important to quantify the extent of verapamil metabolism in order to interpret such P-gp activity. Therefore, we developed a rapid solid-phase extraction (SPE) method to separate, and then quantify, verapamil and its radiolabeled metabolites in plasma. Methods: Using high-performance liquid chromatography (HPLC), we established that the major identifiable circulating radioactive metabolite of [11C]-verapamil in plasma of humans and the nonhuman primate, Macaca nemestrina, was [11C]-D-617/717. Using sequential and differential pH elution on C8 SPE cartridges, we developed a rapid method to separate [11C]-verapamil and [11C]-D-617/717. Recovery was measured by spiking the samples with the corresponding nonradioactive compounds and assaying these compounds by HPLC. Results: Verapamil and D-617/717 recovery with the SPE method was >85%. When the method was applied to PET studies in humans and nonhuman primates, significant plasma concentration of D-617/717 and unknown polar metabolite(s) were observed. The SPE and the HPLC methods were not significantly different in the quantification of verapamil and D-617/717. Conclusions: The SPE method simultaneously processes multiple samples in less than 5 min. Given the short half-life of [11C], this method provides a valuable tool to rapidly determine the concentration of [11C]-verapamil and its [11C]-metabolites in human and nonhuman primate plasma.

Original languageEnglish (US)
Pages (from-to)911-917
Number of pages7
JournalNuclear Medicine and Biology
Volume35
Issue number8
DOIs
StatePublished - Nov 2008
Externally publishedYes

Fingerprint

Solid Phase Extraction
Macaca
Verapamil
P-Glycoprotein
Primates
High Pressure Liquid Chromatography
Positron-Emission Tomography
Macaca nemestrina
Half-Life
Fetus
2-(3,4-dimethoxyphenyl)-5-amino-2-isopropylvaleronitrile
Ligands
Brain

Keywords

  • [C]-Verapamil
  • Human
  • M. nemestrina
  • Macaque
  • Metabolites
  • P-Glycoprotein
  • PET
  • SPE

ASJC Scopus subject areas

  • Cancer Research
  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging

Cite this

Rapid solid-phase extraction method to quantify [11C]-verapamil, and its [11C]-metabolites, in human and macaque plasma. / Unadkat, Jashvant D.; Chung, Francisco; Sasongko, Lucy; Whittington, Dale; Eyal, Sara; Mankoff, David; Collier, Ann C.; Muzi, Mark; Link, Jeanne.

In: Nuclear Medicine and Biology, Vol. 35, No. 8, 11.2008, p. 911-917.

Research output: Contribution to journalArticle

Unadkat, Jashvant D. ; Chung, Francisco ; Sasongko, Lucy ; Whittington, Dale ; Eyal, Sara ; Mankoff, David ; Collier, Ann C. ; Muzi, Mark ; Link, Jeanne. / Rapid solid-phase extraction method to quantify [11C]-verapamil, and its [11C]-metabolites, in human and macaque plasma. In: Nuclear Medicine and Biology. 2008 ; Vol. 35, No. 8. pp. 911-917.
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abstract = "Introduction: P-glycoprotein (P-gp), an efflux transporter, is a significant barrier to drug entry into the brain and the fetus. The positron emission tomography (PET) ligand, [11C]-verapamil, has been used to measure in vivo P-gp activity at various tissue-blood barriers of humans and animals. Since verapamil is extensively metabolized in vivo, it is important to quantify the extent of verapamil metabolism in order to interpret such P-gp activity. Therefore, we developed a rapid solid-phase extraction (SPE) method to separate, and then quantify, verapamil and its radiolabeled metabolites in plasma. Methods: Using high-performance liquid chromatography (HPLC), we established that the major identifiable circulating radioactive metabolite of [11C]-verapamil in plasma of humans and the nonhuman primate, Macaca nemestrina, was [11C]-D-617/717. Using sequential and differential pH elution on C8 SPE cartridges, we developed a rapid method to separate [11C]-verapamil and [11C]-D-617/717. Recovery was measured by spiking the samples with the corresponding nonradioactive compounds and assaying these compounds by HPLC. Results: Verapamil and D-617/717 recovery with the SPE method was >85{\%}. When the method was applied to PET studies in humans and nonhuman primates, significant plasma concentration of D-617/717 and unknown polar metabolite(s) were observed. The SPE and the HPLC methods were not significantly different in the quantification of verapamil and D-617/717. Conclusions: The SPE method simultaneously processes multiple samples in less than 5 min. Given the short half-life of [11C], this method provides a valuable tool to rapidly determine the concentration of [11C]-verapamil and its [11C]-metabolites in human and nonhuman primate plasma.",
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T1 - Rapid solid-phase extraction method to quantify [11C]-verapamil, and its [11C]-metabolites, in human and macaque plasma

AU - Unadkat, Jashvant D.

AU - Chung, Francisco

AU - Sasongko, Lucy

AU - Whittington, Dale

AU - Eyal, Sara

AU - Mankoff, David

AU - Collier, Ann C.

AU - Muzi, Mark

AU - Link, Jeanne

PY - 2008/11

Y1 - 2008/11

N2 - Introduction: P-glycoprotein (P-gp), an efflux transporter, is a significant barrier to drug entry into the brain and the fetus. The positron emission tomography (PET) ligand, [11C]-verapamil, has been used to measure in vivo P-gp activity at various tissue-blood barriers of humans and animals. Since verapamil is extensively metabolized in vivo, it is important to quantify the extent of verapamil metabolism in order to interpret such P-gp activity. Therefore, we developed a rapid solid-phase extraction (SPE) method to separate, and then quantify, verapamil and its radiolabeled metabolites in plasma. Methods: Using high-performance liquid chromatography (HPLC), we established that the major identifiable circulating radioactive metabolite of [11C]-verapamil in plasma of humans and the nonhuman primate, Macaca nemestrina, was [11C]-D-617/717. Using sequential and differential pH elution on C8 SPE cartridges, we developed a rapid method to separate [11C]-verapamil and [11C]-D-617/717. Recovery was measured by spiking the samples with the corresponding nonradioactive compounds and assaying these compounds by HPLC. Results: Verapamil and D-617/717 recovery with the SPE method was >85%. When the method was applied to PET studies in humans and nonhuman primates, significant plasma concentration of D-617/717 and unknown polar metabolite(s) were observed. The SPE and the HPLC methods were not significantly different in the quantification of verapamil and D-617/717. Conclusions: The SPE method simultaneously processes multiple samples in less than 5 min. Given the short half-life of [11C], this method provides a valuable tool to rapidly determine the concentration of [11C]-verapamil and its [11C]-metabolites in human and nonhuman primate plasma.

AB - Introduction: P-glycoprotein (P-gp), an efflux transporter, is a significant barrier to drug entry into the brain and the fetus. The positron emission tomography (PET) ligand, [11C]-verapamil, has been used to measure in vivo P-gp activity at various tissue-blood barriers of humans and animals. Since verapamil is extensively metabolized in vivo, it is important to quantify the extent of verapamil metabolism in order to interpret such P-gp activity. Therefore, we developed a rapid solid-phase extraction (SPE) method to separate, and then quantify, verapamil and its radiolabeled metabolites in plasma. Methods: Using high-performance liquid chromatography (HPLC), we established that the major identifiable circulating radioactive metabolite of [11C]-verapamil in plasma of humans and the nonhuman primate, Macaca nemestrina, was [11C]-D-617/717. Using sequential and differential pH elution on C8 SPE cartridges, we developed a rapid method to separate [11C]-verapamil and [11C]-D-617/717. Recovery was measured by spiking the samples with the corresponding nonradioactive compounds and assaying these compounds by HPLC. Results: Verapamil and D-617/717 recovery with the SPE method was >85%. When the method was applied to PET studies in humans and nonhuman primates, significant plasma concentration of D-617/717 and unknown polar metabolite(s) were observed. The SPE and the HPLC methods were not significantly different in the quantification of verapamil and D-617/717. Conclusions: The SPE method simultaneously processes multiple samples in less than 5 min. Given the short half-life of [11C], this method provides a valuable tool to rapidly determine the concentration of [11C]-verapamil and its [11C]-metabolites in human and nonhuman primate plasma.

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KW - Macaque

KW - Metabolites

KW - P-Glycoprotein

KW - PET

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