en
Scientific article
English

Uptake/efflux transport of tramadol enantiomers and O-desmethyl-tramadol: focus on P-glycoprotein

Published inBasic & clinical pharmacology & toxicology, vol. 105, no. 3, p. 199-206
Publication date2009
Abstract

The analgesic effect of tramadol (TMD) results from the monoaminergic effect of its two enantiomers, (+)-TMD and (-)-TMD as well as its opioid metabolite (+)-O-desmethyl-tramadol (M1). P-glycoprotein (P-gp) might be of importance in the analgesic and tolerability profile variability of TMD. Our study investigated the involvement of P-gp in the transepithelial transport of (+)-TMD, (-)-TMD and M1, using a Caco-2 cell monolayer model. The bidirectional transport of racemic TMD and M1 (1-100 microM) across the monolayers was investigated at two pH conditions (pH 6.8/7.4 and 7.4/7.4) in the presence and absence of P-gp inhibitor cyclosporine A (10 microM) and assessed with the more potent and specific P-gp inhibitor GF120918 (4 microM). Analytical quantification was performed by liquid chromatography coupled to the fluorescence detector. A net secretion of (+)-TMD, (-)-TMD and M1 was observed when a pH gradient was applied (TR: P(app)(B - A)/P(app)(A - B): 1.8-2.7; P < 0.05). However, the bidirectional transport of all compounds was equal in the non-gradient system. In the presence of P-gp inhibitors, a slight but significant increase of secretory flux was observed (up to 26%; P < 0.05) at both pH conditions. In conclusion, (+)-TMD, (-)-TMD and M1 are not P-gp substrates. However, proton-based efflux pumps may be involved in limiting the gastrointestinal absorption of TMD enantiomers as well as enhancing TMD enantiomers and M1 renal excretion. A possible involvement of uptake carriers in the transepithelial transport of TMD enantiomers and M1 is suggested.

Keywords
  • Analgesics, Opioid/pharmacokinetics
  • Biological Transport
  • Caco-2 Cells
  • Electric Impedance
  • Humans
  • Hydrogen-Ion Concentration
  • P-Glycoprotein/physiology
  • Stereoisomerism
  • Tramadol/analogs & derivatives/pharmacokinetics
Citation (ISO format)
KANAAN, Mouna et al. Uptake/efflux transport of tramadol enantiomers and O-desmethyl-tramadol: focus on P-glycoprotein. In: Basic & clinical pharmacology & toxicology, 2009, vol. 105, n° 3, p. 199–206. doi: 10.1111/j.1742-7843.2009.00428.x
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ISSN of the journal1742-7835
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