Physicochemical stability of a metformin solution from three commercial brands

Abstract

Pharmacological management of insulin resistance and dyslipidaemias in children and adolescents is required to prevent the development of metabolic syndrome (MS) and type II diabetes mellitus (DM2). Material and method: we developed extemporaneous formulations from 500 mg-tablets from three generic brands, commercially available in Mexican drugstores: MedimartTM, Farmacias del AhorroTM and Primer NivelTM, dissolved in water sweetened with Splenda, which made them palatable and allowed customised dose adjustment. Solutions were stored at four environmental conditions: 25oC exposed to light, 25oC protected from light, 4oC and 40oC, and their physicochemical stability was assayed. The stability of the drug was determined by ultra performance liquid chromatography and ultraviolet detection (UPLC-UV) and by measuring the pH of the stock solution. The mobile phase consisted of (KH2PO4) 0.1 M, pH = 6.5, 4.6 mM sodium dodecyl sulphate (SDS) and acetonitrile (63:7:30) at 0.8 mL/min, column VARIAN Pursuit C8 150 × 3.9 mm tempered at 40oC, with detection at 236 nm. Results: Metformin from all trademarks was stable at all storage conditions for up to 30 days, retaining more than 90% of the initial amount of active drug, with a pH of 7.4 ± 0.3. Conclusion: Metformin extemporaneous formulations may be developed from either the innovator or generic brands, having the advantage of saving money and conserving the stability of its physicochemical properties. Keywords: Generic metformin, Innovator metformin, Extemporaneous formulation, Physicochemical stability, UPLC-UV.

Keywords

• metformina genérica
• metforfina innovadora
• formulación extemporánea
• estabilidad fisicoquímica
• UPLC-UV