Metformin transport by renal basolateral organic cation transporter hOCT2

Pharm Res. 2005 Feb;22(2):255-9. doi: 10.1007/s11095-004-1193-3.


Purpose: Metformin, an antihyperglycemic agent, is eliminated by tubular secretion in addition to glomerular filtration in the human kidney. This study was performed to characterize metformin transport by human organic cation transporter 2 (hOCT2), the most abundant organic cation transporter in the basolateral membranes of the human kidney.

Methods: Accumulation of [14C]metformin was assessed by the tracer experiments in the human embryonic kidney (HEK293) cells expressing hOCT2.

Results: The transport of [14C]metformin was markedly stimulated in hOCT2-expressing cells compared with the vector-transfected cells. The accumulation of [14C]metformin was concentrative and was dependent on the membrane potential, showing consistency with the characteristics of hOCT2. The apparent Km and Vmax values of [14C]metformin transport by hOCT2-expressing HEK293 cells were 1.38+/-0.21 mM and 11.9+/-1.5 nmol mg protein(-1) min(-1), respectively. The order of the potencies of unlabeled biguanides to inhibit [14C]metformin transport by hOCT2 was phenformin > buformin > metformin. Furthermore, [14C]metformin transport was inhibited slightly or moderately by cationic drugs such as procainamide and quinidine at respective therapeutic concentrations.

Conclusions: Metformin is transported by the basolateral organic cation transporter hOCT2 in the human kidney. hOCT2 could play a role in the drug interactions between metformin and some cationic drugs.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport / physiology
  • Cell Line
  • Dose-Response Relationship, Drug
  • Humans
  • Kidney / metabolism*
  • Metformin / metabolism*
  • Organic Cation Transport Proteins / metabolism*
  • Organic Cation Transporter 2


  • Organic Cation Transport Proteins
  • Organic Cation Transporter 2
  • SLC22A2 protein, human
  • Metformin