Gastroretentive Accordion Pill: Enhancement of riboflavin bioavailability in humans

Leonid Kagan, Noa Lapidot, Michel Afargan, David Kirmayer, Eytan Moor, Yael Mardor, Michael Friedman, Amnon Hoffman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


The purpose of this study was to evaluate the ability of the Accordion Pill™ (AP), a novel controlled release gastroretentive unfolding dosage form (DF), to increase the bioavailability of riboflavin (RF) in humans. Three formulations containing 75 mg of RF and differing in release rate (immediate release (IR) capsule, AP#1, and AP#2) were administered with a low-calorie meal. Gastric residence time (GRT) of the AP was assessed by magnetic resonance imaging. Serial blood and urine samples were taken and assayed for RF. The AP demonstrated prolonged (up to 10.5 h) GRT in humans. Significant elevation in RF bioavailability (209 ± 37%, mean ± S.E.) was achieved by the AP#1 in comparison to the IR capsule. A correlation was established between the in-vitro release rates from DF and bioavailability of RF in humans, and it was modeled taking into account the saturable nature of RF absorption transport and its narrow absorption window (NAW) in the upper gastro-intestinal tract. It is anticipated that the AP will provide a valuable pharmaceutical solution to enhance therapy with NAW drugs.

Original languageAmerican English
Pages (from-to)208-215
Number of pages8
JournalJournal of Controlled Release
Issue number3
StatePublished - 20 Jul 2006

Bibliographical note

Funding Information:
This paper is a part of Leonid Kagan's Ph.D. dissertation. Prof. Amnon Hoffman and Prof. Michael Friedman are affiliated with the David R. Bloom Center for Pharmacy. This research was supported by Intec Pharma Ltd.


  • Controlled release
  • Gastric residence time
  • Narrow absorption window
  • Pharmacokinetics
  • Saturable absorption


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