title: Determination of plasma metformin by a new cation-exchange HPLC technique.
abstract: Metformin is an oral antihyperglycemic agent used in the therapy of noninsulin-dependent diabetic patients. This biguanide can induce dangerous complications such as lactic acidosis when its plasma concentration is too high. For this reason, the determination of plasma metformin should always be done during treatment. We developed a new HPLC method, for the routine determination of plasma metformin, with good reliability, rapid execution, and low costs. Sample preparation involved precipitation of the plasma proteins containing the internal standard buformin with a mixture of methanol, zinc sulfate, and ethylene glycol; the diluted supernatant was injected into a cation-exchange column. The mobile phase was potassium dihydrogenphosphate buffer-containing acetonitrile. The eluent was monitored at 236 nm. The calibration curve is linear within the range of 20-4000 ng/mL; the within-day coefficients of variation were less than 2.2% for metformin and 1.5% for buformin; the day-to-day coefficients of variation were less than 2.5% for metformin and 1.9% for buformin. The mean recoveries obtained from supplemented samples were included between 99.4 and 104.2% for metformin. Many characteristics make this method useful and easily accessible to all clinical laboratories equipped with HPLC instrumentation.
authors.affiliation: Department of Gerontological Research, Center of Biochemistry, INRCA, Ancona, Italy.
authors.forename: A R
authors.initials: AR
authors.lastname: Bonfigli
authors.forename: S
authors.initials: S
authors.lastname: Manfrini
authors.forename: F
authors.initials: F
authors.lastname: Gregorio
authors.forename: R
authors.initials: R
authors.lastname: Testa
authors.forename: I
authors.initials: I
authors.lastname: Testa
authors.forename: G
authors.initials: G
authors.lastname: De Sio
authors.forename: G
authors.initials: G
authors.lastname: Coppa
mesh_terms: D000284:Administration, Oral; D000368:Aged; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002852:Chromatography, Ion Exchange; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000009:adverse effects / Q000097:blood*; D008297:Male; D008687:Metformin / Q000009:adverse effects / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin