Targeted Disruption of Organic Cation Transporter 3 Attenuates the Pharmacologic Response to Metformin

• DOI: 10.1124/mol.114.096776
• Publication Date: 2015-04-29T02:12:41Z
• Authors: Eugene C. Chen; Xiaomin Liang; Sook Wah Yee; Ethan G. Geier; Sophie L. Stocker; Ligong Chen; Kathleen M. Giaco...
• Keywords: Male; 0301 basic medicine; Organic Cation Transport Proteins; Knockout; 610; Biological Availability; Polymorphism, Single Nucleotide; Cell Line; Injections; Mice; 03 medical and health sciences; Cell Line, Tumor; Animals; Humans; Hypoglycemic Agents; Intraperitoneal; Tissue Distribution; Pharmacology & Pharmacy; Polymorphism; Muscle, Skeletal; 3' Untranslated Regions; Mice, Knockout; Tumor; Biomedical and Clinical Sciences; Diabetes; Neurosciences; Pharmacology and Pharmaceutical Sciences; Skeletal; Single Nucleotide; Hep G2 Cells; HCT116 Cells; Healthy Volunteers; Metformin; 3. Good health; Pharmacology and pharmaceutical sciences; Glucose; Adipose Tissue; Gene Expression Regulation; 5.1 Pharmaceuticals; Biochemistry and cell biology; Muscle; Biochemistry and Cell Biology; Injections, Intraperitoneal

Metformin, the most widely prescribed antidiabetic drug, requires transporters to enter tissues involved in its pharmacologic action, including liver, kidney, and peripheral tissues. Organic cation transporter 3 (OCT3, SLC22A3), expressed ubiquitously, transports metformin, but its in vivo role in metformin response is not known. Using Oct3 knockout mice, the role of the transporter in metformin pharmacokinetics and pharmacodynamics was determined. After an intravenous dose of metformin, a 2-fold decrease in the apparent volume of distribution and clearance was observed in knockout compared with wild-type mice (P < 0.001), indicating an important role of OCT3 in tissue distribution and elimination of the drug. After oral doses, a significantly lower bioavailability was observed in knockout compared with wild-type mice (0.27 versus 0.58, P < 0.001). Importantly, metformin's effect on the plasma glucose concentration-time curve was reduced in knockout compared with wild-type mice (12 versus 30% reduction, respectively, P < 0.05) along with its accumulation in skeletal muscle and adipose tissue (P < 0.05). Furthermore, the effect of metformin on phosphorylation of AMP activated protein kinase, and expression of glucose transporter type 4 was absent in the adipose tissue of Oct3(-/-) mice. Additional analysis revealed that an OCT3 3' untranslated region variant was associated with reduced activity in luciferase assays and reduced response to metformin in 57 healthy volunteers. These findings suggest that OCT3 plays an important role in the absorption and elimination of metformin and that the transporter is a critical determinant of metformin bioavailability, clearance, and pharmacologic action.