Noninvasive monitoring of local drug release using x-ray computed tomography: Optimization and in vitro/in vivo validation

Agata Szymanski-Exner, Nicholas T. Stowe, Kyle Salem, Roee Lazebnik, John R. Haaga, David L. Wilson, Jinming Gao

Research output: Contribution to journalArticle

22 Scopus citations


In vivo release profiles of drug-loaded biodegradable implants were noninvasively monitored and characterized using x-ray computed tomography (CT). The imaging method was adapted and optimized to quantitatively examine the release of an active agent from a model cylindrical PLGA device (the millirod) into rabbit livers over 48 h. Iohexol, a CT contrast agent, served as a model drug; optimization of CT acquisition parameters yielded a sensitivity of 0.21 mg/mL (or 95 μg iodine/mL) for this agent. In vitro validation of the method was carried out by tracking release of iohexol in gelatin gel phantoms. In vivo release in rabbit livers was characterized through quantitative analysis of CT images and compared with UV-Vis analysis of the explanted devices at three implantation times. After correction for respiratory motion, CT analysis correlates well with the extracted iohexol data at all time points. The percent error between the actual and experimental image data was below 10%. This study demonstrates the potential of using computed tomography to noninvasively quantify the rate of agent release from controlled delivery devices in vivo.

Original languageEnglish (US)
Pages (from-to)289-296
Number of pages8
JournalJournal of Pharmaceutical Sciences
Issue number2
StatePublished - Feb 1 2003



  • Drug delivery devices
  • Iohexol
  • Noninvasive monitoring
  • X-ray CT

ASJC Scopus subject areas

  • Pharmaceutical Science

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