Pharmacokinetics of metformin after intravenous and oral administration to man.
The kinetics of 14C-metformin have been studied in five healthy subjects after oral and intravenous administration. The intravenous dose was distributed to a small central compartment of 9.9 +/- 1.61 (X +/- SE), from which its elimination could be described using three-compartment open model. The elimination half-life from plasma was 1.7 +/- 0.1 h. Urinary excretion data revealed a quantitatively minor terminal elimination phase with a half-life of 8.9 +/- 0.7 h. After the intravenous dose, metformin was completely excreted unchanged in urine with a renal clearance of 454 +/- 47 ml/min. Metformin was not bound to plasma proteins. The concentration of metformin in saliva was considerably lower than in plasma and declined more slowly. The bioavailability of metformin tablets averaged 50--60%. The rate of absorption was slower than that of elimination, which resulted in a plasma concentration profile of "flip-flop" type for oral metformin.
D000284:Administration, Oral; D000328:Adult; D001944:Breath Tests; D005243:Feces / Q000032:analysis; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007700:Kinetics; D008297:Male; D008687:Metformin / Q000008:administration & dosage / Q000378:metabolism*; D008875:Middle Aged; D011485:Protein Binding; D012463:Saliva / Q000378:metabolism
D008687:Metformin