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Stability-indicating RP-HPLC method for analysis of telmisartan in the bulk drug and in formulations

Londhe S. V, Kaul N., Agrawal H., Mahadik K. R.

Acta Chromatographica

2010

Vol. 22, no. 4

539--548

A sensitive and reproducible HPLC method has been developed for quantitative analysis of telmisartan. The drug was separated from its degradation products on a C 18 column at ambient temperature with methanol-water 80:20 ( v / v ), pH 4.0 (adjusted by addition of orthophosphoric acid), as mobile phase at a flow rate of 1.0 mL min -1. Under these conditions the retention time of telmisartan was 4.85 ± 0.05 min. Quantification on the basis of peak area was achieved by UV detection at 225 nm; calibration plots were linear in the concentration range 10–60 μg mL -1 When the method was applied to a pharmaceutical formulation there was no chromatographic interference from tablet excipients. The method was validated for precision, robustness, recovery, and limits of detection and quantification. The drug was subjected to acidic and alkaline hydrolysis, and oxidising, dry heat, wet heat, and photodegrading conditions. Because the method could effectively separate the drug from its degradation products, it can be regarded as stability indicating.

Separation of bacoside A3 and bacopaside II, major triterpenoid saponins in Bacopa monnieri, by HPTLC and SFC. Application of SFC in implementation of uniform design for herbal drug standardization, with thermodynamic study

Agrawal H., Kaul N., Paradkar A. R., Mahadik K. R.

Acta Chromatographica

2006

No. 17

125-150

Development, optimization, and validation of new analytical methods for standardization of bacoside A3 and bacopaside II, the major triterpenoid saponins present in Bacopa monnieri extract, are needed to improve the quality assurance of derived extracts and phytomedicines. Two chromatographic methods are described for evaluation of the quality of Bacopa monnieri extract and its commercial formulations. The first is reversed-phase high-performance thin-layer chromatography (RP-HPTLC), the second is packed column supercritical-fluid chromatography with photodiode- array detection (PC–SFC–DAD). SFC conditions were optimized by uniform design. The effect of temperature on the separation of the saponins was studied in detail. The Van’t Hoff plots for retention and selectivity were found to be linear. To obtain a better understanding of the different separations, the temperature dependence was studied to determine the thermodynamic data ΔH°, ΔS°, Δ ΔH° and Δ ΔS°. These data revealed that separation of bacoside A3 was enthalpically favoured in the range of temperatures investigated whereas entropy-controlled separation was observed for bacopaside II. Both methods were validated for precision, robustness, recovery, and limits of detection and quantitation. Analysis of variance (ANOVA) and Student’s t-test were used to correlate results from quantitative determination of the markers by RP-HPTLC and PC-SFC–DAD.