Method development and validation for the simultaneous determination of rosiglitazone and metformin in pharmaceutical preparations by capillary zone electrophoresis
Introduction
Many patients suffering from type 2 diabetes require treatment with more than one antihyperglycemic drug to achieve optimal glycemic control. The thiazolidinediones are a novel class of oral antihyperglycemic drugs that improve glycemic control, primarily by increasing peripheral insulin resistance and sensitizing the skeletal muscle, liver and adipose tissue to the actions of insulin, in addition to improving beta-cell function. The combination of metformin hydrochloride (M) (Fig. 1a), a biguanide that enhances glucose uptake in peripheral tissues and reduces hepatic gluconeogenesis, with rosiglitazone maleate (R) (Fig. 1b), one of the newly available members of the thiazolidinedione family, offers a rational therapeutic approach to the treatment of type 2 diabetes [1]. The two agents can be used in combination to achieve additive glucose-lowering efficacy in the treatment of type 2 diabetes, without stimulating insulin secretion and without causing hypoglycaemia [2]. Recently, a single-tablet combination of M and R has become available.
Literature survey reveals several methods for the determination of R in pharmaceutical preparations or in biological fluids including liquid chromatography (LC) [3], [4], [5], [6], [7], [8], [9], liquid chromatography–tandem mass spectrometry (LC/MS–MS) [10], [11] micellar electrokinetic chromatography (MEKC) [3], high performance thin layer chromatography (HPTLC) [12], [13], [14] and spectrophotometry [15]. Several methods have also been described for the determination of M either alone or in combination with various drugs, such as LC [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], LC/MS–MS [29], [30], [31], [32], capillary electrophoresis (CE) [33], spectrophotometry [34], [35], [36], [37] and gas chromatography (GC) [38], [39], [40].To our knowledge, only one study has been published recently for the determination of these two drugs from the combined dosage form, based on LC [41].
CE has been widely used in the past decade for the separation and determination of many substances in pharmaceutical analysis. In some fields, CE is currently displacing LC owing to its many advantageous features, such as extremely high efficiency, high resolution, rapid analysis and small consumption of sample and reagents.
The aim of this study was to demonstrate method development and validation strategies of CE for the analysis of R and M and to describe a capillary zone electrophoretic (CZE) method for the simultaneous determination of R and M. For this purpose, the influence of buffer type, buffer concentration, buffer pH, organic modifier, capillary temperature, applied voltage and injection time was systemically investigated and the method validation studies were performed. The validated method was successfully applied to the pharmaceutical preparations. Although there is a large difference in the label claims of M and R per tablet, simultaneous analysis of these two drugs have been achieved in the same sample preparation.
Section snippets
Apparatus
All CE experiments were performed using an Agilent 3DCE (Waldbronn, Germany) system using ChemStation software, equipped with a diode array UV detector, an automatic sample injector, Peltier temperature controller and 30 kV high voltage power supply. Separation was carried out in a fused-silica capillary 80.5 cm × 75 μm i.d. (effective length 72 cm) in normal mode, applying a voltage of 25 kV. Sample injections were made in a hydrodynamic mode over 3 s under a pressure of 50 mbar.
LC experiment was
Optimization of electrolyte parameters
Manipulation of buffer pH is a key strategy for optimizing the separation of ionizable analytes in CZE because buffer pH determines the extent of the ionization of each analyte and the magnitude of the electroosmotic flow (EOF). Because of decreasing solubility of R in a buffered aqueous solution with increasing pH [42], acidic buffers were tried to prevent its possible precipitation. As R has two pKa values of 6.1 and 6.8 and M has pKa value of 12.4, these two compounds are positively charged
Conclusion
A simple, fast, and reliable CZE method was developed and validated for the simultaneous determination of R and M. The method shows a good performance with respect to specificity, linearity, accuracy, precision and robustness and it offers a simple, fast, inexpensive, and precise way for the determination of R and M in pharmaceutical preparations. The simultaneous determination of R and M in pharmaceutical preparations could be performed accurately, although there was a large difference in the
Acknowledgement
The authors are grateful to Glaxo SmithKline for providing rosiglitazone maleate reference standard and Avandamet® tablets.
References (46)
- et al.
J. Pharm. Biomed. Anal.
(2004) - et al.
J. Chromatogr. B
(2004) - et al.
J. Chromatogr. B
(2003) - et al.
J. Pharm. Biomed. Anal.
(2002) - et al.
J. Chromatogr. B, Biomed. Sci. Appl.
(2001) - et al.
J. Chromatogr. B
(2004) - et al.
J. Chromatogr. B
(2004) - et al.
J. Chromatogr. B
(2005) - et al.
J. Chromatogr. B
(2003) - et al.
J. Pharm. Biomed. Anal.
(2003)