Hepatic Uptake of Octreotide, a Long-Acting Somatostatin Analogue, via a Bile Acid Transport System

Tetsuya Terasaki, Hiroko Mizuguchi, Chizuru Itoho, Ikumi Tamai, Michel Lemaire, Akira Tsuji

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

The hepatic transport mechanism of octreotide (Sandostatin®), a somatostatin analogue, was studied using freshly prepared rat hepatocytes. The initial uptake rate of octreotide represented exclusively a saturable transport process. The half-saturation constant, Kt, and the maximum uptake-rate, Jmax, for the uptake of octreotide were 91.1 ± 28.4 µM and 104.6 ± 19.7 pmol/mg protein/min, respectively. An energy requirement was demonstrated for [14C]octreotide uptake since metabolic inhibitors (DNP, rotenone, antimycin and NaCN) significantly reduced the initial uptake rate. [14C]octreotide uptake was also significantly inhibited by ouabain. [14C]octreotide uptake was reduced in the absence of Na+ in the uptake medium. [14C]octreotide uptake was significantly inhibited by bile acids, iodipamide, d-tubocurarine, whereas it was not inhibited by bilirubin, TEMA and insulin. Competitive inhibition of taurocholic acid was observed for octreotide uptake with the inhibition constant, Ki, of 82 ± 17 µM. Moreover, a significant inhibitory effect of octreotide was observed for the Na + dependent uptake of [14C]taurocholic acid. These results suggest that octreotide is transported into hepatocytes via a bile acid carrier-mediated system.

Original languageEnglish
Pages (from-to)12-17
Number of pages6
JournalPharmaceutical Research: An Official Journal of the American Association of Pharmaceutical Scientists
Volume12
Issue number1
DOIs
Publication statusPublished - 1995 Jan
Externally publishedYes

Keywords

  • bile acid
  • biliary secretion
  • carrier-mediated transport
  • hepatic transport
  • octreotide
  • sandostatin

ASJC Scopus subject areas

  • Biotechnology
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry
  • Pharmacology (medical)

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