Physicochemical stability of three generic brands of metformin in solution

Abstract

Pharmacological management of insulin resistance and dyslipidemias in children and adolescents is mandatory to prevent metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM). Material and method: extemporaneous formulations were developed from 500 mg tablets of three brands of generic metformin: Medimart®, Farmacias del Ahorro®, and Primer Nivel®, with agreeable flavor, color, and consistency and dose adjusted for ease of administration. Their physicochemical integrity was determined under different storage conditions: 25oC with light, 25oC in darkness, at 4oC and 40oC. The stability of the drug was determined by ultra performance liquid chromatography with ultraviolet detection (UPLC-UV) and by measuring the pH of the stored solution; the mobile phase was phosphate buffer (KH2PO4) 0.1 M, pH = 6.5, sodium dodecyl sulfate (SDS) 4.6 mM and acetonitrile (63:7:30) at 0.8 mL/min, VARIAN Pursuit C8 150 × 3.9 mm column tempered at 40oC, with detection at 236 nm. Results: All the commercial brands of metformin were stable under all storage conditions for up to 30 days. They retained more than 90% of the initial quantity of the active drug, with pH of 7.4 ± 0.3. Conclusion: extemporaneous formulations of metformin can be made with both the innovative drug and with generics; money can be saved, with the certainty that they will retain their physicochemical properties.

Keywords

• generic metformin
• innovative metformin
• extemporaneous formulation
• physicochemical stability
• UPLC-UV