ORIGINAL ARTICLESA twin study of the trough plasma steady-state concentration of metforminStage, Tore B.a; Damkier, Pera,c; Pedersen, Rasmus S.a; Christensen, Mette M.H.a; Christiansen, Leneb; Christensen, Kaareb; Brosen, KimaAuthor Information aClinical Pharmacology, Department of Public Health, University of Southern Denmark bEpidemiology, Biostatistics and Biodemography, Department of Public Health, University of Southern Denmark cDepartment of Clinical Chemistry and Pharmacology, Odense University Hospital, Odense, Denmark Correspondence to Tore B. Stage, MSc Pharm, Clinical Pharmacology, Department of Public Health, University of Southern Denmark, J.B. Winslows vej 19, 2nd floor, DK-5000 Odense, Denmark Tel: +45 6550 3678; e-mail: [email protected] Received November 18, 2014 Accepted February 10, 2015 Pharmacogenetics and Genomics: May 2015 - Volume 25 - Issue 5 - p 259-262 doi: 10.1097/FPC.0000000000000133 Buy Metrics Abstract Objective The aim of this study was to determine the intrapair similarity in trough steady-state plasma concentrations of metformin in monozygotic and dizygotic twin pairs. Methods We included 16 twin pairs (eight monozygotic and eight dizygotic twin pairs) for this study after contacting 524 twin pairs. They were dosed with metformin to steady state (1 g twice daily) for 6 days and on day 7, the trough concentration of metformin was determined 12 h after the last dose. Results There was no strong intrapair similarity in trough steady-state plasma concentrations of metformin in either dizygotic or monozygotic twin pairs. Conclusion The trough steady-state plasma concentration of metformin does not appear to be tightly genetically regulated. The interpretation of this finding is limited by the small sample size. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.