Determination of plasma metformin by a new cation-exchange HPLC technique

Anna Rita Bonfigli, Silvana Manfrini, Franco Gregorio, Roberto Testa, Ivano Testa, Giuseppina De Sio, Gilberto Coppa

Research output: Contribution to journalArticle


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.

Original languageEnglish
Pages (from-to)330-334
Number of pages5
JournalTherapeutic Drug Monitoring
Issue number3
Publication statusPublished - Jun 1999


  • Diabetes mellitus
  • HPLC
  • Metformin

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Health, Toxicology and Mutagenesis
  • Pharmacology (medical)
  • Public Health, Environmental and Occupational Health
  • Pharmacology
  • Toxicology

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